6.0L V8 Gas Engine Driveability Module 2
Contents
1. Catalyst Efficiency DTC Description P0133 HO2S Slow Response Bank 1 Sensor 1 P0140 HO2S Circuit Insufficient Activity Bank 1 Sensor 2 P0154 HO2S Circuit Insufficient Activity Bank 2 Sensor 1 P0420 Catalyst System Low Efficiency Bank 1 P0430 Catalyst System Low Efficiency Bank 2 Catalyst Efficiency The ECM monitors the Post Catalyst Oxygen Sensor signals and if there is an indication of low efficiency a DTC will set There may also be symptoms such as a rough hard idle when cold or rattling noise from the converter There may be no noticeable driveability concerns and the only indication is the DTC set TRUCK 40 UNIVERSITY 6 0L V8 Gas Engine Driveability Module 2 Section 3 Heated Oxygen Sensors HO2S Diagnosis Visual Physical Inspection e Inspect sensor electrical connections and harness e Inspect the exhaust system e Check fuel pressure look for vacuum leaks HO2S Diagnosis If engine performance or scan tool data suggest a potential HO2S malfunction don t forget the basics e Always conduct a visual inspection of the electrical connections and wiring harness Electrical connections should be clean and tight Be sure the wiring harness is routed away from hot exhaust pipes e Inspect the exhaust for leaks or holes that may affect the oxygen sensor readings The HO2S measures oxygen so a tightly sealed exhaust system is very important for accurate sensor readings e Remember that improper f2. ISUZU TRUCK 66 UNIVERSITY 6 0L V8 Gas Engine Driveability Module 2 Section 6 Enhanced EVAP System FTP Sensor Fuel Tank Pressure FTP Sensor Fuel Tank Pressure FTP Sensor The reason this is called an Enhanced EVAP system is because of the on board diagnostic capabilities The ECM can perform functional tests to monitor the purge system to detect system leaks lt is the Fuel Tank Pressure FTP Sensor located on the top of the fuel tank sending unit which gives the ECM the necessary feedback to determine if the system Is working properly ISUZU TRUCK 67 any 6 0L V8 Gas Engine Driveability Module 2 Section 6 Enhanced EVAP System EVAP Test Criteria G i r x x V Ya La mE e l 6 a e D m es p eed ste k F k EVAP Test Criteria For the ECM to perform these EVAP tests certain Enabling Criteria must be met For example e No current DITC s can be present and the malfunction indicator lamp must be off e Fuel level must be stable and between 15 and 85 percent e Ambient temperature needs to be between 40 F and 100 F e Vehicle speed and load conditions steady or engine shut off Because these Enabling Criteria are very specific it is possible that the ECM will not run these tests every time the vehicle is driven ISUZU TRUCK lt 68 UNIVERSITY 6 0L V8 Gas Engine Driveability Module 2 Section 6 Enhanced EVAP System EVAP Codes DTC D
3. 6 0L V8 Gas Engine Driveability Module 2 Section 3 Heated Oxygen Sensors Heated Oxygen Sensor Circuit HOT IN ON OR START IN ON OR START Toe Sp 35 Riy paar i PCM Biot button Ale IK nter ph EA109 e Canister Purge Solenoid e MAF IAT Sensor e Bank 1 and Bank 2 Sensor 2 HO2S BRN EA109 BRN EA107 ret sabi D E AN BNIEss EJ A 28 BLU ff EA55 BLU f EA53 0 85 RED BLU WHT h east oye EA54 0 5 GRN 0 5 ms 4 5 6 WHT EA52 WHT EA50 0 85 RED 0 5 12 56 57 HO2S HO2S HO2S HO2S Heater Low High Heater Low Signal Signal Low Control Bank1 Bank 1 Control Bank1 Sensor 1 Sensor 1 Bank 2 HO2S Heater Circuit The Heated Oxygen Sensor HO2S is a four wire sensor two wires carry the signal to the ECM and two wires are for the heater circuit In order for the HO2S to provide an active signal it must be at operating temperature The sensors are located some distance from the engine exhaust ports and would be slow to heat up if relying on just engine temperature Instead the sensors have an internal electric heater that brings them up to operating temperature in just seconds The heater circuit voltage comes from the ignition circuit Once the ignition is turned ON the ECM grounds the heater low control circuit and the HO2S reaches operating temperatures in less than 90 seconds The ECM uses pulse width modulation on the ground side to maintain a steady operating temperature To make sure the heaters are working
4. Misfire Caused by Fuel Delivery 57 Misfire Monitoring 58 Misfire Counters 60 Recorded Misfire Events 61 Misfire Diagnostic Tips 62 CKP Variation Learn Procedure 63 Section6 Enhanced EVAP System 64 Enhanced EVAP Operation 65 FTP Sensor 67 EVAP Test Criteria 68 EVAP Codes 69 EVAP System Large Leak Test 70 Large Leak Fuel Cap OFF 71 EVAP System Small Leak Test 72 EVAP Canister Vent Test 73 EVAP Purge Seal Test 74 Service Tips 75 Acronyms 76 ISUZU TRUCK UNIVERSITY 6 0L V8 Gas Engine Driveability Module 2 section OBD II Diagnostics Diagnostic Strategy Heated Oxygen Sensors Diagnostics Fuel System Diagnostics Misfire Diagnostics Enhanced EVAP System Diagnostics DIRON Course Objectives After completing this course participants will be able to identify and be familiar with OBD II and Diagnostic Trouble Codes Recommended Diagnostic Strategy Scan tool data for Fuel Ignition and Emissions Fuel Trim data Engine Misfire data Enhanced EVAP System diagnostic testing ISUZU TRUCK UNIVERSITY 6 0L V8 Gas Engine Driveability Module 2 Section 1 On Board Diagnostics 6 0L V8 Gas Engine Driveability Module 2 Section 1 On Board Diagnostics II e Description of OBD II e ECM system Monitoring e Diagnostic Trouble Codes e Freeze Frame Failure Records ISUZU TRUCK 4 UNIVERSITY 6 0L V8 Gas Engine Driveability Module 2 Section 1 On Board Diagnostics II Intr
5. 50 UNIVERSITY 6 0L V8 Gas Engine Driveability Module 2 Section 5 Misfire Diagnostics 6 0L V8 Gas Engine Driveability Module 2 Section 5 Misfire Diagnostics e Causes of Engine Misfire e Misfire Monitoring e Misfire Counters e Diagnostic Tips ISUZU TRUCK 51 UNIVERSITY 6 0L V8 Gas Engine Driveability Module 2 Section 5 Misfire Diagnostics Engine Cycles INTAKE COMPRESSION POWER EXHAUST Four Stroke Engine Cycles During normal combustion of a four stroke gasoline engine ignition is a precisely timed occurrence during the compression cycle When the air fuel mixture in the cylinder does not ignite properly it is called Misfire The cause of misfire can be mechanical electrical or related to the fuel system It can also be a combination of these ISUZU TRUCK 52 aa 6 0L V8 Gas Engine Driveability Module 2 Section 5 Misfire Diagnostics Engine Misfire Engine Misfire Although misfire is a common driveability complaint it is not easily diagnosed Symptoms of misfire vary It may cause a rough running engine or the engine may shake so badly that it causes vibrations throughout the vehicle The engine can be hard to start or stall at idle depending on the load Or it may simply cause the engine to feel sluggish or low on power Whatever the symptoms when misfire occurs performance suffers along with fuel economy and emissions 53 6 0L V8 Gas Engine Driveability Module 2 Se
6. Direct Current Vehicle Health Report Vehicle Identification Number Variable Nozzle Turbo ECM Reference Voltage Vehicle Speed Sensor Vacuum Switching Valve Vehicle Theft Deterrent Water In Fuel Warning Light Wide Open Throttle Wheel Speed Sensor 80 ISUZU TRUCK UNIVERSITY
7. Driveability Module 2 Section 4 Fuel System Diagnostics Fuel Trim Codes Description P0171 Fuel Trim System Lean Bank 1 P0172 Fuel Trim System Rich Bank 1 P0174 Fuel Trim System Lean Bank 2 P0175 Fuel Trim system Rich Bank 2 P219A Fuel Trim Cylinder Balance Bank 1 P219B Fuel Trim Cylinder Balance Bank 2 P0230 Fuel Pump Control Circuit Fuel Trim Codes The ECM constantly monitors the Fuel Trim values If they exceed the allowable percentage over a certain time period a DTC will set Note that Fuel Trim Codes are Type B codes so it will take two consecutive ignition cycles with all the Enabling Criteria to be met for the MIL to come on 47 6 0L V8 Gas Engine Driveability Module 2 Section 4 Fuel System Diagnostics Fuel Trim Cylinder Balance S3 Isuzu Diagnostic Service System IDSS x PVCa hH Eaa O 2 2012N Series w 6 0L Gas AUTO JY one s lt Current Vehicle Data Frame 15 2012 H Series 540C441C2CS801790 Date Saved 02 29 42 at 11 42 01 Saved Snapshot Fuel Trim Data Parameter Value Unit 2 Short Term Fuel Trim Bank 1 0 8 Short Term Fuel Trim Bank 2 5 5 Long Term Fuel Trim Bank 1 2 3 Long Term Fuel Trim Bank 2 47 Fuel Trim Learn Enabled Fuel Trim Cell 0 Fuel Trim System Test State Monitoring Short Term Fuel Trim Average Bank 1 3 1 Short Term Fuel Trim Average Bank 2 3 1 Long Term Fuel Trim Average Bank 1 5 5 Long Term Fuel Trim Average Bank 2 0 Long Term Fuel Tr
8. Engine Off EVAP Canister Vent Solenoid Valve Temp Normally Open itii CLOSED On EVAP System Small Leak Test The ECM is also able to detect a very small leak in the EVAP System as small as 020 of an inch or 51 mm It s typical for temperature and pressure to increase in the fuel tank immediately following a drive cycle and the engine is shut off After some time the temperature begins to drop and so does the pressure This can eventually become a vacuum condition if the system is closed tight To make sure there are no small leaks the ECM performs the Small Leak Test After the ignition is turned off and certain Enabling Criteria are met the ECM commands the EVAP Vent Solenoid ON This will completely seal the system and the tank should hold vacuum for a specified time The ECM monitors the FTP Sensor and if the system does not hold vacuum the Small Leak Test will fail and a DTC will set This is a Type A code so the MIL lamp will come on the first time the test fails It s important to note that the ECM may remain active for up to 40 minutes after the ignition is turned off in order to run this test Keep this in mind when performing a Parasitic Draw Test on the vehicle ISUZU TRUCK UNIVERSITY 12 6 0L V8 Gas Engine Driveability Module 2 Section 6 Enhanced EVAP System EVAP Canister Vent Test Purge Solenoid Valve OPEN Normally Closed On Manifold Service
9. One way to check if a misfire condition is because of a rich or lean condition is to check the HO2S data The Long Term Fuel Trim can be very helpful for this Some fuel system conditions that may cause misfire include e Restricted Injectors causing a lean condition e Leaking Injectors causing a rich condition e Electrical conditions causing an Injector not to fire properly e Low fuel pressure due to pinched fuel lines restrictions or low Fuel Pump output e Misfire can also be caused by poor fuel quality or contamination 57 6 0L V8 Gas Engine Driveability Module 2 Section 5 Misfire Diagnostics Misfire Monitoring Reluctor Wheel Misfire Monitoring As stated earlier misfire results in poor fuel economy and excessive tailpipe emissions For this reason the OBD II system has continuous misfire monitoring The ECM can detect a misfire by watching certain inputs mainly the Crankshaft and Camshaft Position Sensors When a misfire occurs that cylinder does not produce the same amount of power as one with normal combustion As a result the crankshaft slows down each time a cylinder misfires The Crankshaft Position Sensor can sense these engine speed fluctuations by the changes in the reluctor wheel speed ISUZU TRUCK 58 SIERT 6 OL V8 Gas Engine Driveability Module 2 Section 5 Misfire Diagnostics Misfire Monitoring Injector Injector 2 Disabled Due to Misfire 3 Disabled Due to Misfire No
10. Test Port Engine Running A as Do EVAP E gt Canister SN E Fresh D IE Air SE a Vent Solenoid Valve Lele Normally Open OPEN Off EVAP Canister Vent Test If there is a restriction in the vent of EVAP system the fuel vapors cannot be purged from the EVAP Canister To test for restrictions while the engine is running the ECM commands the EVAP Purge Solenoid Valve ON The Vent Solenoid Valve stays OFF for this test This opens the Purge Lines between the engine and fuel tank while leaving the Vent Valve open to fresh air If there is a restriction in the Vent Valve a vacuum would build in the fuel tank which would show up on the FTP Sensor signal If the vacuum reaches a specific calibrated value the test fails This is a Type B code so the test must fail twice before a DTC will set ISUZU TRUCK UNIVERSITY 73 6 0L V8 Gas Engine Driveability Module 2 Section 6 Enhanced EVAP System EVAP Purge Seal Test Purge Solenoid Valve on Manifold Service Test Engi NOT Funning SEALING FTP Sensor Wes st Ut Fuel AN Tank Vent Solenoid Valve Normally Open ZXZ CLOSED On j w EVAP z q Canister rt I aH ATG _l EVAP Purge Seal Test If the EVAP Purge Valve does not seal properly fuel vapors could be drawn into the engine at an undes
11. V8 Gas Engine Driveability Module 2 Section 3 Heated Oxygen Sensors Oxygen Sensor Construction _ 2 g OXYGEN SENSOR ELEMENT Oxygen Sensor Construction An Oxygen Sensor is simply a thimble shaped battery that produces a very low voltage less than one volt The inner surface of the sensor is exposed to outside air which contains 21 oxygen This air enters the center of the sensor through the wire connector The outside surface of the Oxygen Sensor element is exposed to exhaust gases containing far less oxygen or no oxygen at all after combustion This difference in oxygen levels in the exhaust verses outside air creates a chemical reaction that produces the very low voltage signal ISUZU TRUCK 21 any 6 OL V8 Gas Engine Driveability Module 2 Section 3 Heated Oxygen Sensors Oxygen Sensor Signal 21 21 OXYGEN OXYGEN 300 MV 0 600 MV 2 J OXYGEN OXYGEN MORE LESS VOLTAGE VOLTAGE 600 MV 450 MV ECM REFERENCE SIGNAL 300 MV Oxygen Sensor Signal Oxygen Sensor output voltage will normally be between 100 and 900 mV When there is a rich air fuel mixture nearly all the oxygen will be burned up during combustion leaving little to no oxygen in the exhaust This produces a higher voltage output from the sensor If the air fuel mixture is lean there is likely to be unburned oxygen in the exhaust The sensor reacts to this by producing a lower voltage 32 ISUZU TRUCK UNIVERSITY
12. if they are current or history Record all DTC s on the repair order for future reference before clearing codes 23 ISUZU TRUCK UNIVERSITY 6 0L V8 Gas Engine Driveability Module 2 Section 2 Diagnostic Strategy Diagnostic Strategy Check Identical Vehicle 1 Understand and Verify the Customer s Concern Customer Misunderstanding of System Explain operation to Vehicle Operating as Designed No customer or refer to owners or Yes 3 Preliminary Checks Visual and Operational Perform Diagnostic System Check Vehicle 5 Check for Bulletins Recalls and Preliminary Information Current DTC Symptom No Intermittent DTC History DTC Follow DTC Follow Analyze and See Diagnostic Diagnostics Symptom Develop Detail Diagnostics Diagnostics or Below Call Technical Assistance service manual Customer Dissatisfied Submit a Field Product Report No Published Diagnostics 7 Re Examine Isolate the Root Cause No the Concern Yes 3 Repair and Verify Fix Diagnostic Strategy Step 5 Step 5 is to check for bulletins This can save a lot of time and effort 24 ISUZU TRUCK UNIVERSITY 6 0L V8 Gas Engine Driveability Module 2 Section 2 Diagnostic Strategy Diagnostic Strategy Check Identical Vehicle 1 Understand and Verify the Customer s Concern Customer Misunderstanding of System Explain operation to Vehicle Operating as Designed customer or refer to owners or Yes No 3 Pre
13. the same Step 1 is to verify the customer s concern It s important to understand this before doing anything else 20 ISUZU TRUCK UNIVERSITY 6 0L V8 Gas Engine Driveability Module 2 Section 2 Diagnostic Strategy Driveability Diagnosis Starting Point Isuzu Repair Service REPAIR ORDER WORK PERFORMED CUSTOMER INFORMATION OTHER Name Ph Date Address Staff City State Zip PAYMENT Make Year Cash Odometer License Check Vin Charge CUSTOMER CONCERNS RATE Labor Hard starting low power stalls and hesitates Serv Call Hourly PM Call CHARGES Labor Hours Parts Down Payment O Yes ONo Amount Gas Oil Grease done salih dhe necessary Guana srani permision 10 operate ea OUtide Repairs to me a mechanic lien may be placed on said vehicle in order to obtain unpaid Storage Fee s n T a a e e in case of fire theft or any other cause beyond our control AMOUNT DUE Customer Signature The Work Order Most driveability diagnosis starts with the work order The first step is understanding what the customer is experiencing and verifying the symptoms It may be necessary to talk to the customer or operate the vehicle if information on the work order is vague or incomplete 21 ISUZU TRUCK UNIVERSITY 6 0L V8 Gas Engine Driveability Module 2 Section 2 Diagnostic Strategy
14. ving Charge And recalls CUSTOMER CONCERNS RATE Check fuel system pressure Labor Fuel pressure low Hard starting low power stalls and hesitates Serv Call Inspect fuel lines and check Hourly Electrical circuit at pump PM Call CHARGES O ee Test drive okay Parts Down Payment O Yes ONo Amount Gas Oil Grease a est Outside Repairs a lies aay be class ongaid click ore oben nnae Staraee Fees 9 repairs services left at Joe s Diesel Service for more than 30 days I understand JDS is not responsible for loss or damage to vehicles or articles left in car trucks Tax in case of fire theft or any other cause beyond our control AMOUNT DUE Customer Signature Diagnostic Strategy Step 8 The final step after the root cause has been identified and the vehicle repaired is to clear codes and verify the fix Remember that some codes require two ignition cycles to turn on the MIL lamp so always recheck for codes when verifying the fix 2 ISUZU TRUCK UNIVERSITY 6 0L V8 Gas Engine Driveability Module 2 Section 3 Heated Oxygen Sensors 6 0L V8 Gas Engine Driveability Module 2 Section 3 Heated Oxygen Sensors HO2S Pre catalyst Heated Oxygen Sensors Post catalyst Heated Oxygen Sensors Catalyst Monitoring Diagnostics and Service ISUZU TRUCK 28 UNIVERSITY Section 3 Heated Oxygen Sensors 6 0L V8 Gas Engine Driveability Module 2 Heated Oxygen Sensor HO2S Heated Oxyge
15. well as electrical or OBD II systems concerns always follow the recommended Diagnostic Strategy and begin with the Diagnostic Starting Point If the MIL lamp is on and there are multiple codes set along with a DTC P0300 it is recommended that you diagnose all other DTC s first before diagnosing the misfire DTC This is because the other codes could be indicating a fault that is causing the misfire One way to pin point a component suspected of causing misfire is to swap parts such as ignition coils plug wires and injectors between cylinders one at a time If the part is at fault the misfire counts will follow the failed part Important Perform a Crankshaft Variation Learn procedure after repairs This should be done only if no other codes are set ISUZU TRUCK CS a 62 UNIVERSITY 6 0L V8 Gas Engine Driveability Module 2 Section 5 Misfire Diagnostics CKP System Variation Learn BY tsuru Diagnaster Service System 1055 Module Engine Datalist CKP Variation Learn Fuel Injector Balance Fuel Tnm Enable Fuel Tam Reset CKP VarationLearn HO2S HeaterLeam TB idle Air Flow Com 4i gt Crankshaft Position CKP Variation Learn Attempts 0 Counts Crankshaft Position CKP Variation Learn Status This Ignition Not Complete Engine Coolant Temperature ECT 18 F Engine Speed S62 RPM AVC Request Signal No Park Neutral Position PNP Switch Park Neutral a Learn Stop Tes Guk Sras Do NOT perf
16. 0L V8 Gas Engine Driveability Module 2 Section 5 Misfire Diagnostics Misfire Events Recorded Types of Catalyst Events e Non Catalyst Damaging Catalyst Damaging Recorded Misfire Events When misfire is detected a DTC P0300 will set The ECM will respond differently depending on how severe the misfire is When a Non Catalyst Damaging Misfire occurs and a DTC sets the MIL lamp comes on solid and stays on This is a misfire that happened only a few times within 1 000 to 3 200 engine revolutions An example of this would be a misfire caused by a partially restricted injector When a Catalyst Damaging Misfire occurs the MIL lamp will flash on and off as long as the condition persists This misfire is happening more frequently within 200 engine revolutions and is considered severe An example of this would be the misfire created by a failed spark plug wire The Catalytic Converter can be damaged from all the unburned fuel in the exhaust and the flashing MIL lamp is a warning to the driver ISUZU TRUCK 61 UNIVERSITY 6 0L V8 Gas Engine Driveability Module 2 Section 5 Misfire Diagnostics Misfire Diagnostic Tips 184 Counts Injector 1 Disabled Due to Misfire No Injector 2 Disabled Due to Misfire No Injector 3 Disabled Oue to Misfire No Inioetar A Mie shlad Mno ta MicAro Na zj i ys SF ca see Resto a eas amn nuna Diagnostic Tips Because DTCs can be set by mechanical as
17. 6 0L V8 Gas Engine Driveability Module 2 Table of Contents Course Outline amp Objectives Section 1 Section 2 Section 3 Introduction to the OBD II Module Communications Controller Message Monitor Module Communications Enabling Criteria Diagnostic Trouble Code DTC DTC Type A DTC Type B DTC Type C Current History DTCs Freeze Frame Failure Records Saving Freeze Frame Data Multiple Codes Service Tips Diagnostic Strategy Driveability Diagnosis Starting Point Diagnostic Strategy step 2 amp 3 Diagnostic Strategy step 4 Diagnostic Strategy step 5 Diagnostic Strategy step 6 Diagnostic Strategy step 7 Diagnostic Strategy step 8 Heated Oxygen Sensors HO2S Oxygen Sensor Location Oxygen Sensor Construction Oxygen Sensor Signal Heated Oxygen Sensor Heater Circuit HO2S Heater Circuit Codes Oxygen Sensor Signal Circuit Pre Catalyst H02S Signal Three way Catalytic Converter Post Catalyst HO2S Signals Catalyst Efficiency HO2S Diagnosis Service Tips Page CON A 11 12 13 14 15 16 17 18 19 21 22 23 24 25 26 2 ISUZU TRUCK UNIVERSITY Table of Contents Page Section 4 Fuel System Diagnostics 43 Closed Loop Mode 44 Fuel Trim Values 45 Fuel Trim 46 Fuel Trim Codes 47 Fuel Trim Cylinder Balance 48 Diagnostic Tips 49 Fuel Trim Reset 50 Section 5 Misfire Diagnostics 51 Engine Cycles 52 Engine Misfire 53 Causes of Misfire 54 Ignition Misfire 56
18. Converter is working efficiently it stores oxygen to be used for converting HC and CO emissions into water vapor and carbon dioxide If the catalyst is functioning correctly and the oxygen storage capacity is working tail pipe emissions are minimal ISUZU TRUCK 38 SD 6 0L V8 Gas Engine Driveability Module 2 Section 3 Heated Oxygen Sensors Post Catalyst H02S Signals E ulti Grsph Display E J aj a f a E y EE mr a E a Sa i L a A Tine ena ar i by HD25 Bank 1 Sensor 2 E94 1080 00 00 l I I I I l I I 2 q il 0 100 120 140 160 120 200 HORES Gank Sensor 579 ee ST ee ee oh 2 Af At BN 170 tins 1 TAO 1 iat 200 1 Post Catalyst HO2S Signal The ECM monitors the catalytic converter efficiency using the Post Catalyst HO2S If the catalyst is working there will be very little fluctuation in the oxygen levels coming out of the converter This is evident by the Post Catalyst HO2S signals being far less active than the signals produced by the Pre Catalyst Oxygen Sensors The signal shown here indicates that the catalytic converter oxygen storage Capacity is at an acceptable level When the response time of the Post Catalyst HO2S are close to that of the Pre Catalyst Sensor this may indicate that the converter is not working properly and may have come apart internally ISUZU TRUCK 39 UNIVERSITY 6 0L V8 Gas Engine Driveability Module 2 Section 3 Heated Oxygen Sensors
19. Diagnostic Strategy Check Identical Vehicle 1 Understand and Verify the Customer s Concern Customer Misunderstanding of System Explain operation to Vehicle Operating as Designed customer or refer to owners or Yes No 3 Preliminary Checks Visual and Operational Perform Diagnostic System Check Vehicle 5 Check for Bulletins Recalls and Preliminary Information Current DTC Symptom No Intermittent DTC History DTC Follow DTC Follow Analyze and See Diagnostic Diagnostics Symptom Develop Detail Diagnostics Diagnostics or Below Call Technical Assistance service manual Customer Dissatisfied Submit a Field Product Report No Published Diagnostics 7 Re Examine Isolate the Root Cause No the Concern Yes 8 Repair and Verify Fix Diagnostic Strategy Step 2 and 3 Step 2 is to determine if the customer s concern is a normal operating characteristic It is very important not to attempt repairs in an attempt to appease the customer if the vehicle is operating as designed It can be helpful to use a known good vehicle for comparison If the customers concern is verified go on to the next step Step 3 is to perform preliminary checks including a very careful visual inspection Don t skip this step because it can often lead to identifying the concern quickly and save time Even if the MIL lamp is on indicating there is a current DTC don t skip the visual inspection A DTC may point you in the rig
20. Eo o nh een 00 k M v r i k fo l j N BOO j j 400 a 20 A g Fa l ae i PT f E wl f l pl y l l l l l l l l l l 240 Aail ADN ABN AN rA A Ai nn 180 AN a Il Ho H H qj Pre Catalyst HO2S Bank 1 Bank2 Signals The ECM monitors the HO2S signal voltage for e response rate e signal range e various other parameters If the sensor signal rate is too slow too fast or the signal is beyond the normal limit the ECM will interpret this as a defective sensor set a DIC and illuminate the MIL When a HO2S signal DTC sets it may not mean the Oxygen Sensor is defective Conditions such as fuel delivery or misfire can also cause these DTCs to set so be sure to follow the diagnostic charts carefully ISUZU TRUCK 3 7 UNIVERSITY 6 0L V8 Gas Engine Driveability Module 2 Section 3 Heated Oxygen Sensors Three way Catalytic Converter H20 C02 3 way Catalyst r gt t M YYA HC CO NOx Three way Catalytic Converter The best air fuel ratio for combustion and emissions control is 14 7 to 1 This air fuel ratio is also what allows the Catalytic Converter to work efficiently The three way Catalytic Converter reduces exhaust gas emissions mainly oxides of nitrogen NOx hydrocarbons HC and carbon monoxide CO In the first stage of the converter the catalyst promotes a chemical reaction which reduces the NOx into nitrogen and oxygen When the Catalytic
21. Inioetar A Die shlaod Mno ta MicAro Na zj LI E G a om Misfire Monitoring on IDSS The ECM uses the Camshaft Position Sensor to determine exactly which cylinder or cylinders the misfire is coming from Here the IDSS screen shows cylinder 4 with a misfire This shows both current and history data which can be helpful to determine how long the condition has been present 99 ISUZU TRUCK UNIVERSITY 6 0 CYL 1 MISFIRES CURRENT di ia CYL 2 MISFIRES CURRENT 0 es il L V8 Gas Engine Driveability Module 2 Misfire Counts CYL 3 MISFIRES el eal Sones CYL 4 MISFIRES CURRENT 36 HISTORY 452 CYL 5 MISFIRES ae al bad ii CYL 6 MISFIRES CURRENT 0 i iia CYL7 MISFIRES cu ada aia RY CYL 8 MISFIRES CURRENT 0 hi i RY Misfire Counters Current and History misfire counts are stored in ECM memory The Misfire Current Counts display real time data Every 200 cylinder firing events the misfire counts are saved in the Misfire History Counts file The History Counts accumulate over time and can be an important diagnostic tool For instance an intermittent misfire may be enough to cause a performance concern but not set a DTC Be aware that Misfire History Counts will reset to zero when you clear codes Be sure to check misfire data before clearing codes to avoid loosing this important diagnostic information 60 Section 5 Misfire Diagnostics ISUZU TRUCK UNIVERSITY 6
22. System Explain operation to Vehicle Operating as Designed No customer or refer to owners or Yes 3 Preliminary Checks Visual and Operational Perform Diagnostic System Check Vehicle 5 Check for Bulletins Recalls and Preliminary Information Current DTC Symptom No Intermittent DTC History DTC Follow DTC Follow Analyze and See Diagnostic Diagnostics Symptom Develop Detail Diagnostics Diagnostics or Below Call Technical Assistance service manual Customer Dissatisfied Submit a Field Product Report No Published Diagnostics 7 Re Examine Isolate the Root Cause No the Concern Yes 3 Repair and Verify Fix Diagnostic Strategy Step 7 Following the Diagnostic Strategy and the procedures as outlined in the service information should eventually lead to finding the root cause of the concern If not it may be necessary to re examine the information from the beginning 26 ISUZU TRUCK UNIVERSITY 6 0L V8 Gas Engine Driveability Module 2 Section 2 Diagnostic Strategy Diagnostic Strategy Isuzu Repair Service REPAIR ORDER WORK PERFORMED CUSTOMER INFORMATION OTHER Name Ph Date Visually inspected vehicle Address Staff Test drive vehicle City State Zip PAYMENT Scan vehicle for DTCs Make Year Cash Found P0300 Odometer License Check Checked for service bulletins
23. TC to view detals MOTE OTCS may take up to 10 seconds to refresh l Diagnostie Trouble Code DTC Current History This IGN Engine DTCs 1 Pid Evaporative Emission EVAP Vent Solenold Control ce E o X X Failed ABS DTCs 0 Powertrain Interface Module PIM DTCs 0 lear All PIH Evaporation Erasion EYAP Ysni Solenoid Co v i Saving Freeze Frame Failure Records It s a good idea to always save Freeze Frame and Failure Records Data before clearing codes If not saved data records will be lost To do this go to the Scan Tool menu in IDSS and click on DTCs 1 Double click on the stored DTC 2 Click on Freeze Frame Failure Records 3 Click Save 4 Click OK After data has been saved click on Utility Functions to open Saved Freeze Frame Failure Records ISUZU TRUCK ce 16 UNIVERSITY 6 0L V8 Gas Engine Driveability Module 2 Section 1 On Board Diagnostics II Multiple Codes 085 tran Diagnostic Service System IDSS 18 x Di Pd oe MER IB QO a 2 22 Series wi o Gas AUTO ry A R Saved Freeze Frame Failure Records Engine P0204 Injector 4 Control Circuit Freeze Frame DTC P0204 Failure Record 1 DTC P0102 Failure Record 2 DTC P0113 Failure Record 3 DTC PO300 Failure Record 4 DTC P0204 Parameter Value List r Engine Load 27 Engine Coolant Temperature ECT 181 F Short Term Fuel Trim Bank 1 1 6 Long T
24. UZU TRUCK UNIVERSITY 6 0L V8 Gas Engine Driveability Module 2 Section 1 On Board Diagnostics II Controller Message Monitor Controller Message Monitor Controller states t3 updated aaproamately every 1 seconds Coentallear Hame fv Engine Active Transmission E Active E ABS Active l Powertrain Interface Module PIM Active Controller Message Monitor Communication between modules can be verified with IDSS using the Controller Message Monitor function This screen shows all modules are active and transmitting data 6 0L V8 Gas Engine Driveability Module 2 Section 1 On Board Diagnostics II MODULE COMMUNICATIONS HOT AT ALL TIMES F 22 ECU Power Batt Distribution 10A _ _ _ _ _ nr nnn 3 BLK HPA12 BLU Data Link Connector Powertrain Interface Engine Control Module ECM TABS Resistor 120 CAN Low Control Unit CAN High EHCU ee ee es J ABS Module Checking Module Communications If there is a failure to communicate between any of the on board modules check the resistance between the high and low circuits of the CAN lines A normal reading should be around 60 ohms If it is 120 ohms or higher there could be a bad resistor in the module or an open in the CAN line ISUZU TRUCK 8 UNIVERSITY 6 0L V8 Gas Engine Driveability Module 2 Section 1 On Board Diagnostics II Enabling Criteria an
25. also referred to as a bias voltage of 450 mV to the HO2S signal wire The ECM determines if the system is rich or lean depending on whether the voltage generated by the sensor is greater than or less than 450 mV ISUZU TRUCK 35 SIERT 6 0L V8 Gas Engine Driveability Module 2 Section 3 Heated Oxygen Sensors em E a T wR Egmulti Graph Display 1700 Pre Catalyst H02S Signal J Mi j w h a CET E ee Time maas r HOJE Hark 1 saran 1 27H TO S00 200 i 320 2 2 A00 28L FELL Fat 2 at 20 380 2 1F0 140 Pre Catalyst HO2S Signal Each time the exhaust valve opens the oxygen levels in the exhaust change This is why the oxygen sensor signal rapidly cycles between 100 and 900 mV while the engine Is running Voltage above 450 mV indicates a rich exhaust and voltage below 450 mV indicates a lean exhaust The ECM is continuously adjusting the fuel to maintain the optimum air fuel ratio This is referred to as Fuel Trim and will be discussed later in this section ISUZU TRUCK 26 SIERT 6 0L V8 Gas Engine Driveability Module 2 Section 3 Heated Oxygen Sensors Pre Catalyst H02S Signals EMulti Graph Display EN 5 s Frane pa o ooo ber ee E T a ae Tns faa amp as s HOGS Bank 1 Sengar 1 729 1000 a00 BOO 400 200 4 l l l l l l l l l 240 220 400 280 260 240 220 200 180 l g ii HO2S Bank 2 Senger 1 569 1000 ll i a Ta iian
26. as the Drive Cycle or Ignition Cycle This is also sometimes referred to as a Trip An example of a Drive Cycle would start when the ignition key is turned ON and includes the vehicle reaching a certain temperature speed and Loop status then end when the vehicle is shut off If all enabling conditions are met and the diagnostic test fails a Diagnostic Trouble Code DTC could set ISUZU TRUCK 9 UNIVERSITY 6 OL V8 Gas Engine Driveability Module 2 Section 1 On Board Diagnostics Diagnostic Trouble Code DTCs EXAMPLE P0137 LOW VOLTAGE BANK 1 SENSOR 2 P0137 B BODY C CHASSIS P POWERTRAIN U NETWORK 0 GENERIC SAE 4 MANUFACTURER SPECIFIC L SPECIFIC FAULT DESIGNATION SPECIFIC VEHICLE SYSTEM Diagnostic Trouble Codes DTCs ah s can be retrieved using the IDSS and are displayed as five digit alphanumeric codes e The first digit is a letter which designates what computer control module it came from For example the ECM or Powertrain module e The second digit is a number which indicates whether it is generic or manufacturer specific e The third digit is a number which points at the specific system For example the number 1 represents Fuel and Air Metering The number 2 represents an injector circuit The ignition system is represented by the number 3 and an auxiliary emission control system by the number 4 e The fourth and fifth digits identify the section of the system that is malfunctio
27. cs Two Outside Diameter Over Drive Original Equipment Output Speed Sensor 18 ISUZU TRUCK UNIVERSITY O2 O2S PCM PCS PCV PIM Acronyms Oxygen Oxygen Sensor Pressure Control Powertrain Control Module Pressure Control Solenoid Positive Crankcase Ventilation Pressure Control Valve Powertrain Interface Module pressure limiter Particulate Matter Preventative Maintenance Park Neutral Position Pressure Switch Power Steering Pounds per Square Inch Power Take Off Pulse Width Modulation Random Access Memory Radiator Coolant Temperature Sensor Read Only Memory Revolutions per minute Regular Production Option Revolutions Per Second Room Temperature Vulcanizing Society of Automotive Engineers selective Catalyst Reduction Suction Control Valve serial Data Gateway Module Stop Lamp Switch Solenoid Shift Solenoid Start Scan Tool service Transmission Lamp Service Vehicle Soon Switch Throttle Actuator Control Tachometer Technical Assistance Line Throttle Body Torque Converter Clutch Transmission Control Module Top Dead Center 79 ISUZU TRUCK UNIVERSITY TFP TFT T M TUTD TWC VAC VCM VDC VHR VIN VNT V ref VSS VSV VTD WIF W L WOT WSS Acronyms Transmission Fluid Pressure Transmission Fluid Temperature Transmission Throttle Position Tap Up Tap Down Three Way Catalytic Converter Volt s Vacuum Volts Alternating Current Vehicle Control Module Voltage
28. ction 5 Misfire Diagnostics Causes of Misfire Service Tools Compression Leak down Tester Tester J 38722 J 35667A Causes of Misfire When the compression in a cylinder is too low the air fuel mixture will not burn properly and can result in misfire Worn components such as Piston rings Cylinder walls Valves or springs Cam to roller lifter contact and Leaking head gaskets can all cause low cylinder compression Procedures that can help diagnose this condition include Cranking Compression Test Cylinder Leak Down Testing and a Running Compression Test Refer to the service information in the engine mechanical section for information on how to perform these procedures or contact Isuzu Technical Assistance for help 54 ISUZU TRUCK UNIVERSITY 6 0L V8 Gas Engine Driveability Module 2 Section 5 Misfire Diagnostics Causes of Misfire Causes of Misfire continued Here are some other conditions to look for When performing a visual inspection check vacuum hoses intake sles the PCV system and valve cover seals for vacuum leaks heck for a restricted air cleaner This can limit the amount of intake air causing the air fuel mixture to be too rich Inspect for damaged or restricted exhaust which can cause higher than normal backpressure This can cause misfire in all cylinders on one bank of the engine If this is the case you may need to use a back pressure gauge like the one shown above Refer to
29. d Drive Cycle Syisuzu Diagnostic Service System IDSS a x Vidi am 5 9 DE 4 2 gt 212 N Series w6 0L Gas AUTO UAN DTC Status Number of DTC s Set Request DTCs Live Data Module Engine Datalist Engine Data Engine Data CMP Actuator Data EVAP Data Fuel Trim Data HO2S Data Ignition Data Induction Data Misfire Data TAC Data Cooling HVAC Data Cruise Data Electrical Theft D4 gt Parameter Value Unit Engine Speed 586 RPM Desired Idle Speed 584 RPM Engine Coolant Temperature ECT 149 F Intake Air Temperature IAT 66 F Ambient Air Temperature 63 F Cold Startup Yes Mass Air Flow MAF 7 gis Air Flow Calculated 6 29 gis Engine Load 25 i Accelerator Pedal Position APP Indicated Angle 0 Throttle Position TP Indicated Angle 5 Manifold Absolute Pressure MAP 31 kPa Intake Manifold Pressure 66 kPa Barometric Pressure 98 kPa Commanded Air Fuel Equivalency Ratio 1 00 1 Loop Status Closed Injector PWM Bank 1 1 3 ms Injector PWM Bank 2 1 3 ms HO2S Bank 1 Sensor 1 629 mV HO2S Bank 1 Sensor 2 777 mV HO2S Bank 2 Sensor 1 673 mV 65 mV z HO2S Bank 2 Sensor 2 Graph Custom Datalists Quick Shap Snapshot Enabling Criteria and Drive Cycle Enabling Criteria is a specific set of conditions that must be met before the ECM can run any of the diagnostic tests Some tests will only run during an extended set of driving procedures known
30. erm Fuel Trim Bank 1 0 Short Term Fuel Trim Bank 2 7 8 Long Term Fuel Trim Bank 2 0 Manifold Absolute Pressure MAP 33 kPa Engine Speed 598 RPM Vehicle Speed 0 mph Spark 14 Intake Air Temperature IAT 79 F Mass Air Flow MAF 7 gis Engine Run Time 00 00 22 hr min sec EVAP Purge Solenoid Command 0 Fuel Tank Level Remaining 23 Warm ups Since DTC Cleared 1 Counts Distance Since DTC Cleared 0 miles Fuel Tank Pressure 0 04 inH20 Barometric Pressure 98 kPa Calculated Three Way Catalyst TWC Temperature Bank 1 435 F Calculated Three Waw Catalhist TWC Tamnerature Rank ABA F zl Multiple Codes Its not uncommon for more than one DTC to be stored When there are multiple codes it can be difficult to know where to begin diagnosis The correct diagnostic strategy is to always start with the first code stored which is the DTC that has saved Freeze Frame data 17 ISUZU TRUCK UNIVERSITY 6 0L V8 Gas Engine Driveability Module 2 Section 1 On Board Diagnostics II Service Tips Service Tips When analyzing scan tool data if a sensor signal is out of range do not assume it is a bad sensor For instance a Mass Air Flow Sensor with a loose or corroded connection will be out of range and can cause poor performance stalling and hard starting This can even cause an intermittent DTC to set The sensor may be OK just the connector needs to be repaired ISUZU TRUCK 18 UNNERSITY 6 0L V8 Gas Engi
31. ers Closed Loop Fuel Control Mode shortly after start up once the Heated Oxygen Sensors HO2S are providing feedback As long as the engine Is running the ECM manages fuel delivery based on the signals from the HO2S and many other critical inputs In Closed Loop the ECM is constantly fine tuning or correcting the fuel delivery to maintain as close to 14 7 1 air fuel ratio as possible This constant correction is called Fuel Trim ISUZU TRUCK 44 UNIVERSITY 6 0L V8 Gas Engine Driveability Module 2 section 4 Fuel System Diagnostics Fuel Trim Values Fuel Trim Conversions Subtracting Fuel Adding Fuel 20 15 10 10 15 20 Percentage Fuel Trim Values Fuel Trim is shown as a positive or negative value that represent the adding or subtracting of fuel from the engine A Positive Fuel Trim Value indicates the ECM is adding fuel in order to compensate for a lean condition A Negative Fuel Trim value indicates that the ECM is reducing the amount of fuel to compensate for a rich condition ISUZU TRUCK 45 UNIVERSITY 6 0L V8 Gas Engine Driveability Module 2 section 4 Fuel System Diagnostics Fuel Trim ENiIsuzu Diagnostic Service System IDSS T x gt bed E amp at 3 O ro ia ned a 2 2012 N Series wi6 0L Gas AUTO wea A R Current Vehicle Data Frame 0 2012 N Series 540C441C2CS801790 Date Saved 02 29 12 at 11 38 49 Saved Snapshot Fuel Trim Data Parameter Value Unit Short Term Fuel Tri
32. escription Type MIL Evaporative Emission EVAP System Small Leak Detected A On Evaporative Emission EVAP Purge Solenoid Control Circuit B On Evaporative Emission EVAP Vent System Performance On Evaporative Emission EVAP Vent Solenoid Control Circuit On Fuel Tank Pressure FTP Sensor Circuit Performance On Fuel Tank Pressure FTP Sensor Circuit Intermittent On Evaporative Emission EVAP System Large Leak Detected On Evaporative Emission EVAP System Flow During Non Purge On EVAP Codes This is a list of some of the Diagnostic Trouble Codes specific to the EVAP System Refer to the service information for more on these DTC s and additional Enhanced EVAP System diagnostics 69 6 0L V8 Gas Engine Driveability Module 2 Section 6 Enhanced EVAP System EVAP System Large Leak Test Purge Solenoid Valve CLOSED Normally Closed Off L rig Manifold 10 f 2 Service Test as 34 Port Engine Running EVAP Canister gt d Fuel Tank Vent Solenoid Valve Normally Open XXS 7 CLOSED POSION On EVAP System Large Leak Test One of the functional tests that the ECM performs is the Large Leak Test While the engine is running the ECM turns ON both the Vent and the Purge Solenoid Valves This will close the Vent Valve and open the Purge Valve allowing engine vacuum to draw on the fuel tank The ECM then monitors the FTP Sensor to see if the system is able
33. g Term Fuel Trim Bank 2 0 Manifold Absolute Pressure MAP 33 kPa Engine Speed 598 RPM Vehicle Speed 0 mph Spark 14 Intake Air Temperature IAT 79 F Mass Air Flow MAF 7 gis Engine Run Time 00 00 22 hr min sec EVAP Purge Solenoid Command 0 Fuel Tank Level Remaining 23 Warm ups Since DTC Cleared 1 Counts Distance Since DTC Cleared 0 miles Fuel Tank Pressure 0 04 inH20 Barometric Pressure 98 kPa Calculated Three Way Catalyst TWC Temperature Bank 1 435 F Caleulated Three Waw Cataliet TWC Tamnerature Rank 2 ARA F As stated earlier when a Type A or B code sets the ECM saves a record of data The data saved is of actual engine conditions at the time that the failure occurred and is viewed on the scan tool as Freeze Frame Failure Records This record will include many critical parameters such as Engine Coolant Temperature Fuel Trim Engine Speed and Vehicle Speed It s important to note that if more than one DTC is stored only the code stored first will store a Freeze Frame Record Additional codes will store only Failure Records This information can be very helpful when trying to diagnose an intermittent condition 15 ISUZU TRUCK UNIVERSITY 6 0L V8 Gas Engine Driveability Module 2 Section 1 On Board Diagnostics II Saving Freeze Frame Data Eaisuzu Diagnosi Service System 1055 _ Miley QF 2012 N Series wi8 0L Gas AUTO WUA Total DTCs 1 eee le Double click on a O
34. hanced Evaporative Emissions or EVAP System is to prevent fuel vapor from escaping into the atmosphere Fuel vapors from the tank are stored in a Charcoal Canister until they can be routed through the Vapor Lines to the intake manifold and burned during normal combustion The Vent Solenoid is located on the EVAP Canister and is normally open to allow fresh air into the canister The Purge Solenoid located in the vapor line between the canister and the engine is normally closed so vapors cannot be drawn into the engine until the right running conditions are met ISUZU TRUCK 65 UNIVERSITY 6 0L V8 Gas Engine Driveability Module 2 Section 6 Enhanced EVAP System Enhanced EVAP Operation Purge Solenoid Valve OPEN e Normally Closed On Manifold f 4 Service Test Port Engine Running f ii EVAP E lt Canister Meen Fresh D IE Air Nae Vent Solenoid Valve AN Normally Open OPEN l Off Enhanced EVAP System Operation Under certain running conditions the ECM will purge the fuel vapors from the canister by commanding the Purge Solenoid to turn ON This opens the valve and allows engine vacuum to draw on the EVAP Canister The EVAP Vent solenoid remains OFF and in the open position allowing fresh air to be drawn through the canister The air mixes with the stored fuel vapors and is pulled into the intake manifold to be burned during normal combustion
35. ht direction but sometimes it can be misleading It s also important to keep in mind that the OBD II system assumes that the mechanical systems are all functioning properly With all the electronics on the vehicle it s easy to overlook the basic mechanical systems ISUZU TRUCK 29 UNIVERSITY 6 0L V8 Gas Engine Driveability Module 2 Section 2 Diagnostic Strategy Diagnostic Strategy Check Identical Vehicle 1 Understand and Verify the Customer s Concern Customer Misunderstanding of System Explain operation to Vehicle Operating as Designed customer or refer to owners or Yes No 3 Preliminary Checks Visual and Operational Perform Diagnostic System Check Vehicle 5 Tai Check for Bulletins Recalls and Preliminary Information Current DTC Symptom No No Published Intermittent DTC Diagnostics History DTC Follow DTC Follow Analyze and See Diagnostic Diagnostics Symptom Develop Detail Diagnostics Diagnostics or Below Call Technical Assistance service manual Customer Dissatisfied Submit a Field Product Report 7 Re Examine Isolate the Root Cause No the Concern Yes 3 Repair and Verify Fix Diagnostic Strategy Step 4 Step 4 is to perform the Diagnostic System Check This is found in the service manual and performing this check will e Identify what control modules are commanding the system e Verify the ability of the control modules to communicate e And identify if any DTCs are stored and
36. im Average wio Purge Bank 1 0 Long Term Fuel Trim Average wio Purge Bank 2 0 Loop Status Closed HO2S Bank 1 Sensor 1 864 mY HO2S Bank 1 Sensor 2 747 mV HO2S Bank 2 Sensor 1 803 mY HO2S Bank 2 Sensor 2 742 mV Injector PWM Bank 1 1 4 ms Injector PWM Bank 2 1 3 ms Hot Open Loop Inactive Catalytic Converter Protection Active No Dawar Enrishmant Inastiva z Fuel Trim Cylinder Balance On the scan tool the Fuel Trim Average is shown as a percentage and helps identify a rich or lean condition that is occurring in one bank of the engine For example if only one cylinder is rich perhaps from a leaking injector the HO2S Sensor on that bank may not be completely out of range but the ECM will consistently see signals that are above the desired value The number shown as the Fuel Trim Average is one way to narrow down which bank has a cylinder that is richer than the others A positive number indicates there is a lean condition and a negative number indicates a rich condition ISUZU TRUCK 48 UNIVERSITY 6 0L V8 Gas Engine Driveability Module 2 Section 4 Fuel System Diagnostics Diagnostic Tips Beware of non OE Parts such as e Oxygen Sensor e Air Filters e Exhaust components All can cause DTCs Diagnostic Tips Non OE sensors an incorrect part number or certain aftermarket parts such as oxygen sensors and air filters can cause DTCs to set Induction system modifications or non OE exhaust system c
37. ired time This can change the air fuel mixture and cause driveability concerns To monitor for this condition the ECM performs the EVAP Purge Seal Test While the engine is running the ECM leaves the Purge Solenoid OFF and commands the Vent Solenoid ON while monitoring the FTP Sensor This should completely seal the system and pressure in the fuel tank should not change If the ECM detects any vacuum in the fuel tank it means that the EVAP Purge Valve is not sealing properly If the vacuum in the fuel tank gets above a calibrated value a DTC can set This is a Type B code so the test must fail on two consecutive drive cycles before the MIL lamp comes on ISUZU TRUCK UNIVERSITY 14 6 0L V8 Gas Engine Driveability Module 2 Section 6 Enhanced EVAP System Service Tips S3isuzu Diagnostic Service System IDSS e xj gt bad A me E is S Oe 2012 N Series wi6 0L Gas AUTO ae R _ Service Information Electrical Schematics Model Year 2012 Engine 6 0L i Model N Series f Output Control Test Preview Taneman AUTO Controller Programming Module Engine Utility Functions Datalist EVAP Purge Seal o Saved Snapshots gt al gt T Savod France Fiama Failure Records CMP Actuator CMP Actuator Solenoid EC Ignition Relay EWAP Purge Solenoid EVAP Vent Solenoid Dai Purge Seal Fuel Purp F __ Manage Custom Datalists Parameter Unit _ Scan Tool Preview EVAP Purge Solenoid Command EVAP Yent S
38. liminary Checks Visual and Operational Perform Diagnostic System Check Vehicle 5 Tai Check for Bulletins Recalls and Preliminary Information Current DTC Symptom No No Published Intermittent DTC Diagnostics History DTC Follow DTC Follow Analyze and See Diagnostic Diagnostics Symptom Develop Detail Diagnostics Diagnostics or Below Call Technical Assistance service manual Customer Dissatisfied Submit a Field Product Report 7 Re Examine Isolate the Root Cause No the Concern Yes 8 Repair and Verify Fix Diagnostic Strategy Step 6 In Step 6 the diagnostic path will be determined by what was learned from the Diagnostic System Check e fthere is a current code follow the correct procedure in the service manual If there are multiple codes start with the first code set e f symptoms seem to be intermittent check for a history code If there is one refer to the DTC chart in the service manual This may help get to the root cause e Ifthere are no codes stored diagnostics will be based on the emissions or drivability conditions e fthere is no code and no published diagnostics related to the concern it may be necessary to call the Technical Assistance Center ISUZU TRUCK 25 UNIVERSITY 6 0L V8 Gas Engine Driveability Module 2 Section 2 Diagnostic Strategy Diagnostic Strategy Check Identical Vehicle 1 Understand and Verify the Customer s Concern Customer Misunderstanding of
39. m Bank 1 3 9 Short Term Fuel Trim Bank 2 1 6 Long Term Fuel Trim Bank 1 6 3 Long Term Fuel Trim Bank 2 6 3 Fuel Trim Learn Enabled Fuel Trim Cell 14 Fuel Trim System Test State Monitoring Short Term Fuel Trim Average Bank 1 0 Short Term Fuel Trim Average Bank 2 0 Long Term Fuel Trim Average Bank 1 5 5 Long Term Fuel Trim Average Bank 2 0 a Long Term Fuel Trim Average wio Purge Bank 1 5 5 Long Term Fuel Trim Average wio Purge Bank 2 6 3 Loop Status Closed HO2S Bank 1 Sensor 1 820 mV HO2S Bank 1 Sensor 2 855 mV HO2S Bank 2 Sensor 1 165 mY HO2S Bank 2 Sensor 2 829 mV Injector PWM Bank 1 1 6 ms Injector PWM Bank 2 1 7 ms Hot Open Loop Inactive Catalytic Converter Protection Active No Dawar Envriehmant Inactive z Bee Short Term Long Term Fuel Trim Fuel Trim can be viewed using a scan tool and is useful when diagnosing driveability concerns Short Term Fuel Trim represents the constant fine tuning of the fuel delivery system Short Term Fuel Trim values show what the current fuel correction is in response to the input signal from the Pre Catalyst Oxygen Sensors Long Term Fuel Trim values on the other hand are the fuel delivery corrections that has been learned over time This is a coarser fuel correction that the ECM stores in long term memory to adjust for rich or lean conditions or to compensate for normal wear and aging ISUZU TRUCK 46 UNIVERSITY 6 0L V8 Gas Engine
40. n Sensors HO2S The 6 0L gas engine has four Heated Oxygen Sensors also referred to as HO2S that provide important information to the ECM for fuel control and catalytic converter monitoring ISUZU TRUCK UNIVERSITY 29 6 0L V8 Gas Engine Driveability Module 2 Section 3 Heated Oxygen Sensors Oxygen Sensor Location Bank 1 Sensor 1 Bank 2 Sensor 1 Bank 2 Sensor 2 Bank 1 Sensor 2 Oxygen Sensor Location The two Pre Catalyst Oxygen Sensors are located in the exhaust pipes before the catalytic converters The signals from the Pre Catalyst Oxygen Sensors provide critical information to the ECM when the system is in Closed Loop By monitoring the Oxygen Sensor signals the ECM constantly adjusts fuel delivery trying to maintain an air to fuel ratio of 14 7 1 the optimal air fuel ratio for low emissions and driveability The ECM uses the two Post Catalyst Oxygen Sensor signals to monitor the efficiency of the Catalytic Converters The Pre Catalyst Oxygen Sensor on the driver side is referred to as Bank 1 Sensor 1 Bank 1 Sensor 2 is a Post Catalyst Oxygen Sensor and is located on the passenger side after the Catalytic Converter This is because the exhaust pipes cross over The Pre Catalyst Oxygen Sensor on the passenger side is referred to as Bank 2 Sensor 1 Bank 2 Sensor 2 is a Post Catalyst Oxygen Sensor and is located after the Catalytic Converter on the driver side ISUZU TRUCK 30 UNIVERSITY 6 0L
41. ne Driveability Module 2 Section 2 Diagnostic Strate 6 0L V8 Gas Engine Driveability Module 2 Section 2 Diagnostic Strategy e Introduction to Diagnostic Strategy e Diagnostic Starting Point e Code or No Code Diagnostics ISUZU TRUCK 19 UNIVERSITY 6 0L V8 Gas Engine Driveability Module 2 Section 2 Diagnostic Strategy Diagnostic Strategy Check Identical Vehicle 1 Understand and Verify the Customer s Concern Customer Misunderstanding of Vehicle Operating as Designed System Explain operation to customer or refer to owners or Yes service manual Customer Dissatisfied Submit a Field Product Report No 3 Preliminary Checks Visual and Operational Perform Diagnostic System Check Vehicle 5 TE Check for Bulletins Recalls and Preliminary Information Current DTC Symptom No No Published Intermittent DTC Diagnostics History DTC Follow DTC Follow Analyze and See Diagnostic Diagnostics Symptom Develop Detail Diagnostics Diagnostics or Below Call Technical Assistance 7 Re Examine Isolate the Root Cause No the Concern Yes 8 Repair and Verify Fix Diagnostic Strategy Step 1 Strategy Based Diagnosis provides a systematic approach to diagnosing the vehicle in other words a plan of action Using this strategy helps reduce diagnostic time and improves the chances to fix it right the first time Each customer s concern may be different but the basic Diagnostic Strategy is always
42. ning which will be defined when referencing the service information 10 ISUZU TRUCK UNIVERSITY 6 0L V8 Gas Engine Driveability Module 2 Section 1 On Board Diagnostics II DTC Type A Examples e P0120 Throttle Position TP Sensor 1 Circuit e P0122 Throttle Position sensor 1 Circuit Low Voltage e P0123 Throttle Position Sensor 1 Circuit High Voltage DTC Type A Type A Diagnostic Trouble Codes DTCs are the most serious and will turn on the Malfunction Indicator Lamp MIL as soon as the ECM detects a problem Some ell die of Type A codes are P0120 which means that the ECM has identified a malfunction on Throttle Position Sensor 1 Circuit e P0122 indicating the ECM is seeing low voltage on the Throttle Position Sensor 1 Circuit e P0123 indicating that the ECM is seeing high voltage on the Throttle Position Sensor 1 Circuit When a Type A code is set the OBD II system stores it as a History code It also stores Freeze Frame and Failure Record Data This stored data can be very helpful in diagnosing the problem and will be discussed later in this section ISUZU ae 11 Davee 6 0L V8 Gas Engine Driveability Module 2 Section 1 On Board Diagnostics II DTC Type B Examples e P0101 Mass Air Flow MAF Sensor Performance e P0116 Engine Coolant Temperature ECT Sensor Performance DTC Type B Type B Codes indicate a fault but of a less serious concern to vehicle emissi
43. oduction to OBD Il OBD II was first introduced in the mid 1990 s and is a sophisticated computer system that controls the engine and emissions operations This system has extensive diagnostic capabilities that can monitor detect and report vehicle emissions and performance malfunctions When the vehicle s on board computer detects a failure in an emissions related component or system the computer e assigns a very specific diagnostic trouble code or DTC e saves the code in the computer s memory and e may light up the Malfunction Indicator Lamp MIL ISUZU TRUCK 5 UNIVERSITY 6 0 L V8 Gas Engine Driveability Module 2 Section 1 On Board Diagnostics II MODULE COMMUNICATIONS F 22 Power k Spite Batt Distribution Relay t Lan In Cab 3 BLK A PA12 BLU 0 85 Data Link E 253 253 Connector Fa DLC Fa 6257 BLK TFO3 an Powertrain Voltage Interface lon High Engine Control Module ECM Module Communications As discussed in Module 1 the main components of the OBD II system are the Engine Control Module ECM the Transmission Control Module TCM the Powertrain Interface Module PIM and the Anti Lock Brake System ABS module The various modules communicate with each other and the diagnostic scan tool equipment through a dual wire high soeed communication link called the CAN Bus The Scan Tool connects to the Bus through the Data Link Connector DLC IS
44. olenoid Command Fuel Tank Pressure Fuel Tank Pressure Sensor Fuel Tank Level Remaining Engine Speed inH20 Volts RPM Return Service Tips lf manual leak testing is required this can be done using the PURGE SEAL function of the IDSS Output Control Test This test commands the EVAP Purge Solenoid OFF and EVAP Vent Solenoid ON at the same time while observing the FTP Sensor signal This should seal the system to any venting With the engine running this should create a vacuum in the fuel tank If there is an external leak the system will not hold vacuum To find the exact location of the leak there is an Evaporative Emissions System Tester available through SPX This tool can be very helpful in diagnosing intermittent system leaks It introduces smoke into the EVAP system so technicians can visibly check for leaks This is not an Isuzu essential tool therefore it is not covered in the service information so contact SPX for more information ISUZU TRUCK UNIVERSITY 79 A AMP ABS AC A C ACC A F AOH APP AT ATDC ATF BARO Bat BCM B BHP BTDC CAC CAN CBR CC CEL CID CKP CKT cm CMP CNG CO2 CPP CSV Cu In DEF DEFCM DIC DLC DMM DOC DPF DRL Acronyms Ampere s Anti lock Brake System Alternating Current Air Conditioning Accessary Air Fuel Ratio Air Over Hydraulic Accelerator Pedal Position Sensor Automatic Transmission After Top Dead Center Automatic Transmis
45. omponents can affect the HO2S signals and fuel delivery Be sure to look for these conditions when doing the preliminary visual inspection ISUZU TRUCK 49 r 6 0L V8 Gas Engine Driveability Module 2 Section 4 Fuel System Diagnostics Fuel Trim Reset ISS Extra Diagnostic Service System IDSS b la xj r Aye i Ways A 5 Se PIC ce OF ES he OD 2 2012 N Series wi 0L Gas AUTO o 1 fa a Model Year 2012 Engine 6 0L Output Control Test Preview Teena E Module Engine eee S Throttle Position Cylinder Power Balance Fuel Injector Balance Fuel Trim Enable CKP Variation Learn HO2S Hex 4 gt Parameter Unit Fuel Trim Learn Fuel Trim Cell Short Term Fuel Trim Bank 1 Short Term Fuel Trim Bank 2 Long Term Fuel Trim Bank 1 Long Term Fuel Trim Bank 2 as 3s Fuel Trim Reset After doing any type of performance repair it is a good idea to reset Fuel Trim This will reset the Long Term Fuel Trim values back to zero percent and the fuel delivery back to factory preset values Skipping this step could cause poor performance until the ECM has had time to relearn Fuel Trim on it s own To do this go to the Scan Tool menu in IDSS and click on Output Control Tests 1 Then click on Engine 2 Advance the arrow on the right to get to Fuel Trim Reset and click on it 3 Click the Reset box 4 Then Stop Test Return to Data Display and click on Fuel Trim Data to view changes ISUZU TRUCK O
46. ons An example of a Type B Code would be e P0101 Mass Air Flow Sensor Performance e P0116 Engine coolant Temperature Sensor Performance In the case of a Type B Code the fault must occur on two consecutive Drive Cycles before the MIL lamp will come on If a fault occurs during one Drive Cycle but not during the next the code won t mature and the MIL lamp will remain off Only when all the conditions are met on two back to back Drive Cycles will a History Code set and the MIL lamp come on ISUZU TRUCK CS a 12 UNIVERSITY 6 0L V8 Gas Engine Driveability Module 2 Section 1 On Board Diagnostics II DTC Type C Example of Type C Codes Non Emission related e U0140 Lost Communication with Powertrain Interface Module PIM e P0564 Cruise Control Multi Function Switch Circuit DTC Type C Type C Codes are non emission related These codes do not turn on the MIL lamp but may turn on a separate indicator lamp such as the SERVICE VEHICLE SOON LIGHT An example of a Type C Code would be e U0140 Lost Communication with Powertrain Interface Module e P0564 Cruise Control Multi function Switch Circuit ISUZU TRUCK 13 UNIVERSITY 6 0L V8 Gas Engine Driveability Module 2 Section 1 On Board Diagnostics II Current History DTCs 7 12 x ia OD gt 2012 N Series wi6 0L Gas AUTO wl Wea Total DTCs 4 Double click on a DTC to view details NOTE DTCS may take up to 10 seconds to refresh Diagnostic Tro
47. orm the CKP Leam Procedure twice in one ignition cycle 1 Place the transmission in park and set the parking brake 2 Start the engine and allow the ECT t0 reach a1 feast 158 F 70 C then let the engine idle 3 Turn OFF all accessories headlights A C blower etc A Hold the brake pedal with your left foot E As mentioned in Module 1 it is a good idea to perform a Crankshaft Variation Learn Procedure after certain repairs This is done by selecting ECM Output Control Test CKP Variation Learn tab in IDSS This resets and calibrates the Crankshaft Position Sensor CKP to reluctor wheel relationship Follow the Test Criteria provided in the box on the screen TRUCK T 63 UNIVERSITY 6 0L V8 Gas Engine Driveability Module 2 Section 6 Enhanced EVAP System 6 0L V8 Gas Engine Driveability Module 2 Section 6 Enhanced EVAP System e System operation e Diagnostic Trouble Codes e System Monitoring and Diagnostic Tests e Diagnostic Service Tips ISUZU TRUCK 64 UNIVERSITY 6 0L V8 Gas Engine Driveability Module 2 Section 6 Enhanced EVAP System Enhanced EVAP Operation Purge Solenoid Valve CLOSED Off fom Normally Closed Manifold Service Test Port Engine Running FTP Sensor yer EAP CDO h onl Air S il Sab Vent Solenoid Valve Ue Normally Open r a ent OPEN Off Enhanced EVAP System Operation The purpose of the En
48. scharge Electronic Trailer Brake Controller Evaporative Emissions System Exhaust Fuel Pump Fuel Rail Pressure regulator sensor Fuel Rail Pressure Reduction Valve Fuel Tank Pressure Fuel Temperature sensor Generator General Motors in vehicle Local Area Network Ground Glow Plug Control Module Gross Vehicle Weight Rating Hydraulic Brake Booster Hydrocarbons Heated Oxygen Sensor Heater Vent Air Conditioning Idle Air Control Intake Airflow Valve Intake Air Temperature Sensor Ignition Coil Integrated Circuit Ignition Control Idle Control Solenoid Identification Inside Diameter Isuzu Diagnostic Service System 11 ISUZU TRUCK UNIVERSITY IGN IMS In Inj Int IP IPC IQC ISC ISS km km h KPa KS kV kW lb ft lb in LPG mA MAF MAP MID MIL mm MMU MPa MPH M T Acronyms Ignition Internal Mode Switch Inch Injector Intake Instrument Panel Instrument Panel Cluster Isuzu Quality Center Idle Speed Control Input Speed Sensor Kilograms Kilometers Kilometers per Hour KiloPascals Knock Sensor Kilovolts Kilowatts Liter Foot Pounds Inch Pounds Liquefied Petroleum Gas Milliamps Mass Air Flow Manifold Absolute Pressure Multi Information Display Malfunction Indicator Lamp Millimeter Mimamori Unit MegaPascal Miles per Hour Manual Transmission Millivolt Naturally Aspirated Normally Closed Newton Meter Normally Open Nitrogen Oxides of On Board Diagnosti
49. sion Fluid Barometric Pressure Battery Body Control Module Battery Positive Voltage Brake Horsepower Before Top Dead Center Charge Air Cooler Controller Area Network Clutch Braking Cubic Centimeter Check Engine Light Cubic Inch Displacement Crankshaft Position Sensor Circuit Centimeter Camshaft Position Sensor Compressed Natural Gas Carbon Monoxide Carbon Dioxide Clutch Pedal Position Clutch Select Valve Cubic Inch Direct Current Diesel Exhaust Fluid Diesel Exhaust Fluid Control Module Driver Information Center Diagnostic Link Connector Digital Multimeter Diesel Oxidation Catalyst Diesel Particulate Filter Daytime Running Lights 76 ISUZU TRUCK UNIVERSITY DRM DSC DSR DTC DVOM EBCM EBD ECCC ECM ECT EEPROM EGR EGT EHCU El EMI EOP ESD ETBC EVAP EXH FP FRP FRPRV FTP FT GEN GMLAN GND GPCM GVWR HBB HC HO2S HVAC IAC IAF IAT IC ICS ID IDSS Acronyms Data Recording Module Driver Shift Control Driver Shift Request Diagnostic Trouble Code Digital Volt Ohm Meter Electronic Brake Control Module Electronic Braking force Distribution Electronically Controlled Capacity Clutch Electronic Control Module Engine Coolant Temperature Sensor Electronically Erasable Programmable Read Only Memory Exhaust Gas Recirculation Exhaust Gas Temperature Electronic Hydraulic Control Unit Electronic Ignition Electromagnetic Interference Engine Oil Pressure Electrostatic Di
50. the ECM monitors the amperage and the voltage on the HO2S heater low control circuit If the ECM detects something out of range a DTC will set ISUZU TRUCK 33 UNIVERSITY 6 0L V8 Gas Engine Driveability Module 2 Section 3 Heated Oxygen Sensors HO2S Heater Circuit Codes DTC Description HO2S Heater Circuit Codes There are 42 codes associated with the HO2S and 12 of these codes are associated with the heater circuit lf an Oxygen Sensor heater circuit code sets don t assume the heater element has failed It s a good idea to inspect the wiring and connectors leading to the sensor for possible damage TRUCK A 34 UNIVERSITY 6 0L V8 Gas Engine Driveability Module 2 Section 3 Heated Oxygen Sensors Oxygen Sensor Signal Circuit HOT IN ON OR START IN ON OR START re F 35 kez paar PCM Eer Hle Jis enter I aes EA109 e Canister Purge Solenoid e MAF IAT Sensor e Bank 1 and Bank 2 Sensor 2 HO2S apt f f Abe ia D E TTA B NIE EB A J 126 BLU f EA55 BLU EA53 0 85 RED WHT hl E51 oa EA54 0 5 GRN 05 a 4 5 6 WHT EA52 WHT 4 EA50 ae 0 85 RED 05 BLU EA55 BLU f EA53 BLU EA54 yT BLK 0 5 12 56 57 13 60 59 HO2S HO2S HO2S HO2S HO2S HO2S Heater Low High Heater Low High Low Signal Signal Low Signal Signal Control Bank 1 Bank 1 Control Bank 2 Bank 2 Bank1 amp Sensor 1 Sensor 1 Bank 2 Sensor 1 Sensor 1 HO2S Signal Circuit The ECM applies a reference voltage
51. the service information for exhaust system diagnosis 99 ISUZU TRUCK UNIVERSITY 6 0L V8 Gas Engine Driveability Module 2 Section 5 Misfire Diagnostics Ignition Misfire OU 4 oi Ty x Ww f pii A ri i Aa l Ai T f oT TaullVv S53PdIn WEhtia tn Beet wae ar s A SG i gep A A l Py At gt 4 a F y 4 N 1 p Ignition Misfire A no spark condition is a common cause of misfire This can be due to e worn or fouled spark plugs e worn or faulty spark plug wires e weak or failed ignition coil or wire harness connections For the ignition system to function it must have adequate voltage If the alternator output is low it can cause a no spark condition The same is true if there is a poor battery cable connection or if engine grounds are loose or corroded These conditions also affect the available voltage for the ignition system to function properly ISUZU TRUCK 56 UNIVERSITY 6 0L V8 Gas Engine Driveability Module 2 Section 5 Misfire Diagnostics Misfire Caused by Fuel Delivery Shh Whit sii TIOTITE MULLE s e pom 5 em F cCoO ar natio r fy pi ait f Misfire Caused by Fuel Delivery For normal combustion to take place there must be the right amount of fuel and air in the cylinder If the mixture is too lean or too rich it may not ignite and burn even if there is a spark
52. to reach a specific level of vacuum within a set amount of time Next the ECM commands the EVAP Purge Solenoid Valve OFF This seals the system and the ECM monitors the FTP Sensor to see if the vacuum holds If the specific vacuum level is not reached or the vacuum does not hold once the system is sealed the system fails the Large Leak Test Since this is a Type B failure code the system must fail this test on two consecutive trips before a DTC will set ISUZU TRUCK 70 UNIVERSITY 6 0L V8 Gas Engine Driveability Module 2 Section 6 Enhanced EVAP System Large Leak Fuel Cap Off Purge Solenoid Valve CLOSED ss Normally Closed Off Intake ft E Manifold Service Test Port Engine Running FTP Sensor EVAP Canister Vent Solenoid Valve Normally Open CLOSED On Large Leak Test Fuel Cap Off The most common condition for the Large Leak Test to fail is when the fuel fill cap is not tightened properly after a refueling The ECM can detect when the vehicle has been refueled based on information from the Fuel Sender unit and may run a Large Leak Test right away This is a Type B code so it may take several trips for the MIL lamp to come on ISUZU TRUCK 71 r 6 0L V8 Gas Engine Driveability Module 2 Section 6 Enhanced EVAP System EVAP System Small Leak Test Purge Solenoid Valve CLOSED Normally Closed Off O Intake Manifold Service Test Port
53. uble Code DTC Current History This IGN Engine DTCs 4 P0102 Mass Air Flow MAF Sensor Circuit Low Frequency X Failed P0113 Intake Air Temperature IAT Sensor 1 Circuit High Voltage xX Failed P0204 Injector 4 Control Circuit xX Failed P0300 Engine Misfire Detected xX Failed Transmission DTCs 0 ABS DTCs 0 Powertrain Interface Module PIM DTCs 0 P0300 Engine Misfire Detected ZA Current History DTCs Current codes are based on real time data and reflect conditions that are currently present Type A codes stay current until cleared History codes are stored in ECM memory and indicate a failure occurred but may not be currently present This IDSS screen shows both e An Intermittent condition can cause a History code to be stored in memory If it is a Type B code and the failure hasn t occurred two consecutive times it isn t mature yet so the MIL lamp may not come on ISUZU TRUCK 14 UNIVERSITY 6 0L V8 Gas Engine Driveability Module 2 Section 1 On Board Diagnostics II Freeze Frame Failure Records Freeze Frame Failure Records Isuzu Diagnostic Service System IDSS l la x Pid Ow 88 Ea O 7 2Wi2Nn Series wi6 0L Gas AUTO waa Saved Freeze Frame Failure Records Engine P0204 Injector 4 Control Circuit Parameter Value List z Engine Load 27 Engine Coolant Temperature ECT 181 F Short Term Fuel Trim Bank 1 1 6 Long Term Fuel Trim Bank 1 0 Short Term Fuel Trim Bank 2 78 Lon
54. uel pressure or vacuum leaks can also cause HO2S readings to be out of range ISUZU TRUCK D S 41 UNIVERSITY 6 0L V8 Gas Engine Driveability Module 2 Section 3 Heated Oxygen Sensors Service tips Heated Oxygen Sensor Heater Contact Wire Leads Heater Extends into tip Zirconium Dioxide Ceramic Thimble Sensing Element Reference Air Tube cover with slots Service Tips If the heated oxygen sensor pigtail wiring connector or terminals are damaged replace the entire heated oxygen sensor assembly Do not attempt to repair it In order for the sensor to function properly a clean air reference must pass through the sensor wires Any attempt to repair the wires connectors or terminals could result in the obstruction of the air reference and degrade sensor performance When installing an oxygen sensor apply anti seize to the threads only Avoid getting the anti seize anywhere else on the sensor and refer to service information for proper torque ISUZU TRUCK 42 ancy 6 0L V8 Gas Engine Driveability Module 2 Section 4 Fuel System Diagnostics 6 0L V8 Gas Engine Driveability Module 2 Section 4 Fuel System Diagnostics e Closed Loop Fuel Control e Short and Long Term Fuel Trim e Diagnostic Tips ISUZU TRUCK 43 UNIVERSITY 6 0L V8 Gas Engine Driveability Module 2 Section 4 Fuel System Diagnostics Closed Loop Mode Closed Loop Mode As discussed in module 1 the system ent
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