EMISSION CONTROL SYSTEMS
Contents
1. 4 Install the front bumper fascia assembly and grill Refer to Group 23 Body EVAPORATIVE CANISTER PURGE SOLENOID REMOVAL The duty cycle evaporative EVAP canister purge solenoid is located in the left front corner of the engine compartment on all engine emission packages Fig 17 WINDSHIELD WASHER RESERVOIR BOTTLE LEFT FRONT FENDER ELECTRICAL CONNECTOR DUTY CYCLE EVAP CANISTER PURGE SOLENOID E FY FS E BS ES FE FS BRACKET EZ MOUNTING E NUTS 2 5 S 80a0c513 Fig 17 EVAP Canister Purge Solenoid Typical 1 Disconnect the electrical connector at the sole noid 2 Disconnect the vacuum lines at the solenoid 3 Remove the two bracket mounting nuts and remove solenoid INSTALLATION 1 Position the solenoid to vehicle 2 Install and tighten the two bracket mounting nuts to 5 N m 45 in Ibs torque 3 Connect the vacuum lines to the solenoid Be sure the vacuum lines are firmly connected and not leaking or damaged If leaking a Diagnostic Trouble Code DTC may be set with certain emission pack ages 4 Connect the electrical connector to the solenoid ROLLOVER VALVE S The rollover valves s are is molded into the fuel tank and are not serviced separately If replacement is necessary the fuel tank must be replaced Refer to Fuel Tank Removal Installation in Group 14 Fuel System for procedures LEAK DETECTION PUMP LDP The LDP is located in the left front corner of the e2. 32 P0753 Trans 3 4 Shift Sol Trans Relay Circuits Current state of output port for the solenoid is different from expected state 89 P0112 Intake Air Temp Sensor Voltage Low Intake air temperature sensor input below the maximum acceptable voltage or 3A P0113 Intake Air Temp Sensor Voltage High Intake air temperature sensor input above the minimum acceptable voltage 3D P0204 Injector 4 Control Circuit Injector 4 output driver does not respond properly to the control signal SE P0132 Left Upstream O2S Shorted to Voltage Oxygen sensor input voltage maintained above the normal operating range 44 PO600 PCM Failure SPI Communications POM internal fault condition detected P0205 Injector 45 Control Circuit Injector 5 output driver does not respond properly to the control signal or 46 P0206 Injector 46 Control Circuit Injector 6 output driver does not respond properly to the control signal AR e ZJ EMISSION CONTROL SYSTEMS 25 5 DESCRIPTION AND OPERATION Continued Generic Scan Tool DRB Scan Tool Display Description of Diagnostic Trouble Code Voltage less than 1 55 volts Voltage greater than 3 76 volts Injector 7 output driver does not respond properly to the control signal Injector 8 output driver does not respond properly to the control signal Speed control switch input above the maximum acceptable voltage Speed control switch input below the minimum acceptable voltage Oxygen sensor response slo
3. as a conventional EMISSION CONTROL SYSTEMS 25 15 J8925 14 Fig 8 High Intake Manifold Vacuum Minimal Vapor Flow J8925 15 Fig 9 Moderate Intake Manifold Vacuum Maximum Vapor Flow FIXED ORIFICE FITTING AIR INLET FITTING AIR CLEANER COVER 80a0c510 Fig 10 CCV System 4 0L Engine PCV system but does not use a vacuum controlled valve A molded vacuum tube connects a fitting on the intake manifold to a fixed orifice fitting of a cali brated size This fitting meters the amount of crank case vapors drawn out of the engine The fixed orifice fitting is located on the top rear of cylinder head valve cover Fig 10 25 16 EMISSION CONTROL SYSTEMS DESCRIPTION AND OPERATION Continued A fresh air supply hose is connected between a fit ting on the air cleaner housing and the air inlet fit ting at the top front of cylinder head cover Fig 10 When the engine is operating fresh air enters the engine and mixes with crankcase vapors Engine vac uum draws the vapor air mixture through the fixed orifice and into the intake manifold The vapors are then consumed during engine combustion CRANKCASE BREATHER FILTER 5 2L 5 9L ENGINE The crankcase breather filter Fig 11 is located on the cylinder head valve cover The filter may be cleaned by washing in kerosene or similar solvent Filter must then be thoroughly drained More fre quent service may be necessary for vehicles operated exte
4. spark plug cables CYLINDER COMPRESSION The PCM cannot detect uneven low or high engine cylinder compression EXHAUST SYSTEM The PCM cannot detect a plugged restricted or leaking exhaust system although it may set a fuel system fault FUEL INJ ECTOR MECHANICAL MALFUNCTIONS The PCM cannot determine if a fuel injector is clogged the needle is sticking or if the wrong injector is installed However these could result in a rich or lean condition causing the PCM to store a diagnostic trouble code for either misfire an oxygen sensor or the fuel system EXCESSIVE OIL CONSUMPTION Although the PCM monitors engine exhaust oxygen content when the system is in closed loop it cannot determine excessive oil consumption THROTTLE BODY AIR FLOW The PCM cannot detect a clogged or restricted air cleaner inlet or filter element LOAD VALUE EMISSION CONTROL SYSTEMS 25 11 VACUUM ASSIST The PCM cannot detect leaks or restrictions in the vacuum circuits of vacuum assisted engine control System devices However these could cause the PCM to store a MAP sensor diagnostic trouble code and cause a high idle condition PCM SYSTEM GROUND The PCM cannot determine a poor system ground However one or more diagnostic trouble codes may be generated as a result of this condition The mod ule should be mounted to the body at all times also during diagnostic PCM CONNECTOR ENGAGEMENT The PCM may not be able to determine spread or dama
5. AND OPERATION MALFUNCTION INDICATOR LAMP MIL As a functional test the MIL check engine illumi nates at key on before engine cranking Whenever the Powertrain Control Module PCM sets a Diag nostic Trouble Code DTC that affects vehicle emis sions it illuminates the MIL If a problem is detected the PCM sends a message to the instru ment cluster to illuminate the lamp The PCM illu minates the MIL only for DTC s that affect vehicle emissions There are some monitors that may take two consecutive trips with a detected fault before the MIL is illuminated The MIL stays on continu ously when the PCM has entered a Limp In mode or identified a failed emission component Refer to the Diagnostic Trouble Code charts in this group for emission related codes Also the MIL either flashes or illuminates contin uously when the PCM detects active engine misfire Refer to Misfire Monitoring in this section Additionally the PCM may reset turn off the MIL when one of the following occur e PCM does not detect the malfunction for 3 consec utive trips except misfire and Fuel system Monitors e PCM does not detect a malfunction while per forming three successive engine misfire or fuel sys tem tests The PCM performs these tests while the ZJ engine is operating within 375 RPM of and within 10 of the load of the operating condition at which the malfunction was first detected STATE DISPLAY TEST MODE The switch inputs to t
6. C 572 to 662 F the sensor generates a voltage that is inversely propor tional to the amount of oxygen in the exhaust The information obtained by the sensor is used to calcu late the fuel injector pulse width This maintains a 14 7 to 1 Air Fuel A F ratio At this mixture ratio the catalyst works best to remove hydrocarbons HC carbon monoxide CO and nitrogen oxide NOx from the exhaust The O2S is also the main sensing element for the Catalyst and Fuel Monitors The O2S can fail in any or all of the following manners e slow response rate e reduced output voltage e dynamic shift e shorted or open circuits Response rate is the time required for the sensor to switch from lean to rich once it is exposed to a richer than optimum A F mixture or vice versa As the sen sor starts malfunctioning it could take longer to detect the changes in the oxygen content of the exhaust gas The output voltage of the O2S ranges from O to 1 volt A good sensor can easily generate any output voltage in this range as it is exposed to different con centrations of oxygen To detect a shift in the A F mixture lean or rich the output voltage has to change beyond a threshold value A malfunctioning ZJ sensor could have difficulty changing beyond the threshold value OXYGEN SENSOR HEATER MONITOR If there is an oxygen sensor 02S shorted to volt age DTC as well as a O2S heater DTC the O2S fault MUST be repaired first Before check
7. INST FINGER J9325 16 Fig 13 Check Vacuum at PCV Valve Typical 2 Install the PCV valve Remove the crankcase breather filter Hold a piece of stiff paper such as a parts tag loosely over the opening of crankcase breather filter at the cylinder head valve cover Fig 14 3 The paper should be drawn against the opening in the cylinder head valve cover with noticeable force This will be after allowing approximately one minute for crankcase pressure to reduce 4 Turn engine off and remove PCV valve from cylinder head valve cover The valve should rattle when shaken Fig 15 ZJ DIAGNOSIS AND TESTING Continued CRANKCASE BREATHER OPENING ENGINE VALVE COVER STIFF PAPER PLACED OVER OPENING CRANKCASE BREATHER REMOVED J9325 17 Fig 14 Check Vacuum at Crankcase Breather Opening Typical PCV VALVE GROMMET uL h pL SN IIT i EL sli PCV VALVE MUST RATTLE Fig 15 Shake PCV Valve Typical 5 Replace the PCV valve and retest the system if it does not operate as described in the preceding tests Do not attempt to clean the old PCV valve 6 If the paper is not held against the opening in cylinder head valve cover after new valve is installed the PCV valve hose may be restricted and must be replaced The passage in the intake manifold must also be checked and cleaned 7 To dean the intake manifold fitting turn a 1 4 inch dril
8. ORATION EVAP CANISTER A maintenance free EVAP canister is used on all vehicles The EVAP canister is located below the left front headlamp Fig 2 The EVAP canister is filled with granules of an activated carbon mixture Fuel vapors entering the EVAP canister are absorbed by the charcoal granules Fuel tank pressure vents into the EVAP canister Fuel vapors are temporarily held in the canister until ZJ DESCRIPTION AND OPERATION Continued they can be drawn into the intake manifold The duty cycle EVAP canister purge solenoid allows the EVAP canister to be purged at predetermined times and at certain engine operating conditions MOUNTING NUTS 4 LEFT FRONT FENDER EVAP CANISTER 80a0c511 Fig 2 EVAP Canister Location DUTY CYCLE EVAP CANISTER PURGE SOLENOID The 4 0L six cylinder and 5 2L 5 9L V 8 engines are equipped with a duty cycle EVAP canister purge solenoid The solenoid regulates the rate of vapor flow from the EVAP canister to the intake manifold The Powertrain Control Module PCM operates the solenoid During the cold start warm up period and the hot start time delay the PCM does not energize the sole noid When de energized no vapors are purged The PCM de energizes the solenoid during open loop oper ation The engine enters closed loop operation after it reaches a specified temperature and the time delay ends During closed loop operation the PCM cycles energizes and de energizes the so
9. SYSTEMS 25 19 4 Connect electrical connector to LDP 5 Install EVAP canister purge solenoid 6 Install air cleaner housing Refer to Group 14 Fuel System for procedures SPECIFICATIONS TORQUE CHART Description Torque EVAP Canister Mounting Nuts 9 N m 80 in Ibs EVAP Canister Purge Solenoid Mounting Nuts 5 N m 45 in Ibs LDP Pump Bracket Nuts Bolts 7 N m 65 in Ibs LDP Filter Mounting Bolts 7 N m 65 in Ibs
10. Torq Conv Clu No RPM Drop At Lockup P0462 Fuel Level Sending Unit Volts Too Low 7E 80 84 87 8A 8D 8E 94 95 or Fuel Level Sending Unit Volts Too High ui Fuel Level Unit No Change Over Miles P1493 Ambient Batt Temp Sen VoltsToo Low or P1492 Ambient Batt Temp Sensor VoltsToo High P0131 Left Bank and Upstream O2S Shorted to Ground or P0137 Downstream Left Bank Downstream and Pre Catalyst O2S Shorted to Ground P0442 Evap Leak Monitor Small Leak Detected or P0455 P0711 Trans Temp Sensor No Rise After Start Evap Leak Monitor Large Leak Detected 97 99 9A oB 9C 9D AO A1 4 A Left Bank Downstream or Downstream and Pre Catalyst O2S Shorted to Voltage P0125 Closed Loop Temp Not Reached P0121 TPS Voltage Does Not Agree With MAP TPS signal does not correlate to MAP sensor P1296 No 5 Volts To MAP Sensor 5 Volt output to MAP sensor open P1294 Target Idle Not Reached ZJ Description of Diagnostic Trouble Code Oxygen sensor input voltage maintained above the normal operating range Engine does not reach 20 F within 5 minutes with a vehicle speed signal Actual idle speed does not equal target idle speed Governor sensor input not between 10 and 25 psi when requested Governor pressure greater than 3 psi when requested to be 0 psi Relationship between engine speed and vehicle speed indicates no torque converter clutch engagement auto trans only Open c
11. ZJ EMISSION CONTROL SYSTEMS 25 1 EMISSION CONTROL SYSTEMS CONTENTS ON BOARD DIAGNOSTICS INDEX page page GENERAL INFORMATION LOAD VALUH a 11 EYSIEM DESCRIPTION 1 MALFUNCTION INDICATOR LAMP MIL 2 DESCRIPTION AND OPERATION MONITORED SYSIEMS 7 VENERE 2 NON MONITOBED CIRCUITS 10 EOMPONENIMONHORS 10 BIAIE DISPLAY TEST MODE 2 DIAGNOSTIC TROUBLE CODES 2 TRIP DEEINITION oaa 10 HIGH ANDIOWLIMIS 11 GENERAL INFORMATION SYSTEM DESCRIPTION The Powertrain Control Module PCM monitors many different circuits in the fuel injection ignition emission and engine systems If the PCM senses a problem with a monitored circuit often enough to indicate an actual problem it stores a Diagnostic Trouble Code DTC in the PCM s memory If the code applies to a non emissions related component or system and the problem is repaired or ceases to exist the PCM cancels the code after 40 warm up cycles Diagnostic trouble codes that affect vehicle emissions illuminate the Malfunction Indicator check engine Lamp Refer to Malfunction Indicator Lamp in this section Certain criteria must be met before the PCM stores a DTC in memory The criteria may be a spe cific range of engine RPM engine temperature and or input voltage to the PCM The PCM might not store a DTC for a monitored circuit even
12. anifold The PCV ZJ DESCRIPTION AND OPERATION Continued system manages crankcase pressure and meters blow by gases to the intake system reducing engine sludge formation THROTTLEBODY AIR CLEANER a a INTAKE z x Ny yr Se soe 1 CRANKCASE USTI BREATHER FILTER COMBUSTION CHAMBER BLOW BY GASES J9325 21 Fig 6 Typical Closed Crankcase Ventilation System The PCV valve contains a spring loaded plunger This plunger meters the amount of crankcase vapors routed into the combustion chamber based on intake manifold vacuum When the engine is not operating or during an engine pop back the spring forces the plunger back against the seat This will prevent vapors from flow ing through the valve J9025 20 Fig 7 Engine Off or Engine Pop Back No Vapor Flow During periods of high manifold vacuum such as idle or cruising speeds vacuum is sufficient to com pletely compress spring It will then pull the plunger to the top of the valve Fig 8 In this position there is minimal vapor flow through the valve During periods of moderate manifold vacuum the plunger is only pulled part way back from inlet This results in maximum vapor flow through the valve Fig 9 CRANKCASE VENTILATION CCV SYSTEM 4 0L ENGINE 4 0L 6 cylinder engines are equipped with a Crankcase Ventilation CCV system The CCV sys tem performs the same function
13. atalyst this ratio will be one to one indicating that no oxidation occurs in the device The system must be monitored so that when cata lyst efficiency deteriorates and exhaust emissions increase to over the legal limit the MIL check engine lamp will be illuminated TRIP DEFINITION The term Trip has different meanings depending on what the circumstances are If the MIL Malfunc tion Indicator Lamp is OFF a Trip is defined as when the Oxygen Sensor Monitor and the Catalyst Monitor have been completed in the same drive cyde When any Emission DTC is set the MIL on the dash is turned ON When the MIL is ON it takes 3 good trips to turn the MIL OFF In this case it depends on what type of DTC is set to know what a Trip is For the Fuel Monitor or Mis Fire Monitor contin uous monitor the vehide must be operated in the Similar Condition Window for a specified amount of time to be considered a Good Trip If a Non Contiuous OBDII Monitor such as Oxygen Sensor Catalyst Monitor Purge Flow Monitor Leak Detection Pump Monitor if equipped EGR Monitor if equipped Oxygen Sensor Heater Monitor fails twice in a row and turns ON the MIL re run ning that monitor which previously failed on the next start up and passing the monitor is considered to be a Good Trip If any other Emission DTC is set not an OBDII Monitor a Good Trip is considered to be when the Oxygen Sensor Monitor and Catalyst Monitor have been complete
14. by using the stricter evap purge flow monitor At an appropriate warm idle the LDP will be energized to seal the canister vent The purge flow will be clocked up from some small value in an attempt to see a shift in the 02 control system If fuel vapor indicated by a shift in the 02 control is present the test is passed If not it is assumed that the purge system is not functioning in some respect The LDP is again turned off and the test is ended MISFIRE MONITOR Excessive engine misfire results in increased cata lyst temperature and causes an increase in HC emis sions Severe misfires could cause catalyst damage To prevent catalytic convertor damage the PCM monitors engine misfire EMISSION CONTROL SYSTEMS 25 9 The Powertrain Control Module PCM monitors for misfire during most engine operating conditions positive torque by looking at changes in the crank shaft speed If a misfire occurs the speed of the crankshaft will vary more than normal FUEL SYSTEM MONITOR To comply with dean air regulations vehides are equipped with catalytic converters These converters reduce the emission of hydrocarbons oxides of nitro gen and carbon monoxide The catalyst works best when the Air Fuel A F ratio is at or near the opti mum of 14 7 to 1 The PCM is programmed to maintain the optimum air fuel ratio of 14 7 to 1 This is done by making short term corrections in the fuel injector pulse width based on the O2S sensor output The
15. curances AB P0748 Governor Pressure Sol Control Trans Current state of solenoid output port is different Relay Circuits than expected AD P1765 Trans 12 Volt Supply Relay Ctrl Circuit Current state of solenoid output port is different than expeted Cylinder 5 Mis fire Misfire detected in cylinder 5 DRB Scan Tool Display Description of Diagnostic Trouble Code Cylinder 6 Mis fire Misfire detected in cylinder 6 Cylinder 7 Mis fire Misfire detected in cylinder 7 Cylinder 8 Mis fire Misfire detected in cylinder 8 Leak Detection Pump Solenoid Circuit Leak detection pump solenoid circuit fault open or short or Leak detection pump SW or mechanical Leak detection pump switch does not respond fault to input P1398 No Crank Sensr Learn CKP sensor target windows have too much variation P1486 Evap leak monitor pinched hose Plug or pinch detected between purge solenoid found and fuel tank BC P0751 O D Switch Pressed LO More Than 5 Overdrive Off switch input too low for more than Min 5 minutes B7 B8 BA BB CO P0133 or Cat mon slow O2 1 1 A slow switching oxygen sensor has been P1195 detected in bank 1 1 during catalyst monitor test C2 P0129 or Cat mon slow O2 1 2 A slow switching oxygen sensor has been P1197 detected in bank 1 2 during catalyst monitor test MONITORED SYSTEMS fuel engine ignition and emission systems and thus There are new electronic circuit monitors that the emissions performance of th
16. d or 2 Minutes of engine run time if ZJ the Oxygen Sensor Monitor or Catalyst Monitor have been stopped from running It can take up to 2 Failures in a row to turn on the MIL After the MIL is ON it takes 3 Good Trips to turn the MIL OFF After the MIL is OFF the PCM will self erase the DTC after 40 Warm up cycles A Warm up cycle is counted when the ECT Engine Coolant Temperature Sensor has crossed 160 F and has risen by at least 40 F since the engine has been started COMPONENT MONITORS There are several components that will affect vehi cle emissions if they malfunction If one of these com ponents malfunctions the Malfunction Indicator Lamp Check Engine will illuminate Some of the component monitors are checking for proper operation of the part Electrically operated components now have input rationality and output functionality checks Previously a component like the Throttle Position sensor TPS was checked by the PCM for an open or shorted circuit If one of these conditions occurred a DTC was set Now there is a check to ensure that the component is working This is done by watching for a TPS indication of a greater or lesser throttle opening than MAP and engine rpm indicate In the case of the TPS if engine vacuum is high and engine rpm is 1600 or greater and the TPS indicates a large throttle opening a DTC will be set The same applies to low vacuum if the TPS indicates a small throttle opening All open
17. e the maximum acceptable voltage 19 1A 1B 25 4 EMISSION CONTROL SYSTEMS _ cc Z DESCRIPTION AND OPERATION Continued Generic Scan Tool Code ME P0117 ECT Sensor Voltage Too Low Engine coolant temperature sensor input below minimum acceptable voltage or IF P0118 ECT Sensor Voltage Too High Engine coolant temperature sensor input above maximum acceptable voltage 21 P1281 Engine Is Cold Too Long Engine did not reach operating temperature within acceptable limits 23 P0500 No Vehicle Speed Sensor Signal No vehicle speed sensor signal detected during road load conditions 24 P0107 MAP Sensor Voltage Too Low MAP sensor input below minimum acceptable voltage or 25 P0108 MAP Sensor Voltage Too High MAP sensor input above maximum acceptable I y x DRB Scan Tool Display Description of Diagnostic Trouble Code voltage 27 P1297 No Change in MAP From Start to Run No difference recognized between the engine MAP reading and the barometric atmospheric pressure reading from start up 28 P0320 No Crank Reference Signal at PCM No crank reference signal detected during engine cranking 2B P0351 Ignition Coil 1 Primary Circuit Peak primary circuit current not achieved with maximum dwell time 2C P1389 No ASD Relay Output Voltage at PCM An Open condition Detected In The ASD Relay Output Circuit 31 P1696 PCM Failure EEPROM Write Denied Unsuccessful attempt to write to an EEPROM location by the PCM
18. e vehicle check fuel emission engine and ignition perfor The fuel engine ignition and emission systems mance These monitors use information from various monitors do not indicate a specific component prob sensor circuits to indicate the overall operation of the lem They do indicate that there is an implied prob 25 8 EMISSION CONTROL SYSTEMS DESCRIPTION AND OPERATION Continued lem within one of the systems and that a specific problem must be diagnosed If any of these monitors detect a problem affecting vehide emissions the Malfunction Indicator Check Engine Lamp will be illuminated These monitors generate Diagnostic Trouble Codes that can be dis played with the check engine lamp or a scan tool The following is a list of the system monitors e Misfire Monitor Fuel System Monitor Oxygen Sensor Monitor Oxygen Sensor Heater Monitor Catalyst Monitor e Leak Detection Pump Monitor if equipped All these system monitors require two consecutive trips with the malfunction present to set a fault Refer to the appropriate Powertrain Diagnos tics Procedures manual for diagnostic proce dures The following is an operation and description of each system monitor OXYGEN SENSOR 02S MONITOR Effective control of exhaust emissions is achieved by an oxygen feedback system The most important element of the feedback system is the O2S The O2S is located in the exhaust path Once it reaches oper ating temperature 300 to 350
19. elay Control Circuit An open or shorted condition detected in the auto shutdown relay circuit P0622 Generator Field Not Switching Properly An open or shorted condition detected in the generator field control circuit C P0743 Torque Converter Clutch Soleniod Trans An open or shorted condition detected in the Relay Circuits torque converter part throttle unlock solenoid control circuit 3 speed auto RH trans only OF P1595 Speed Control Solenoid Circuits An open or shorted condition detected in the Speed Control vacuum or vent solenoid circuits 10 P0645 A C Clutch Relay Circuit An open or shorted condition detected in the A C clutch relay circuit 12 P0443 EVAP Purge Solenoid Circuit An open or shorted condition detected in the duty cycle purge solenoid circuit 3 P0203 Injector 3 Control Circuit Injector 3 output driver does not respond properly to the control signal 0 1 d or Injector 2 Control Circuit Injector 2 output driver does not respond properly to the control signal Injector 1 Control Circuit Injector 1 output driver does not respond properly to the control signal P0505 Idle Air Control Motor Circuits A shorted or open condition detected in one or more of the idle air control motor circuits P0122 Throttle Position Sensor Voltage Low Throttle position sensor input below the minimum acceptable voltage EN EN o or P0123 Throttle Position Sensor Voltage High Throttle position sensor input abov
20. energized with a fixed duration pulse Subsequent fixed pulses occur when the diaphragm reaches the Switch closure point The spring in the pump is set so that the system will achieve an equalized pressure of about 7 5 H20 The cycle rate of pump strokes is quite rapid as the system begins to pump up to this pressure As the pressure increases the cycle rate starts to drop off If there is no leak in the system the pump would even tually stop pumping at the equalized pressure If there is a leak it will continue to pump at a rate rep resentative of the flow characteristic of the size of the leak From this information we can determine if the leak is larger than the required detection limit cur rently set at 040 orifice by CARB If a leak is revealed during the leak test portion of the test the test is terminated at the end of the test mode and no further system checks will be performed After passing the leak detection phase of the test system pressure is maintained by turning on the LDP s solenoid until the purge system is activated Purge activation in effect creates a leak The cycle rate is again interrogated and when it increases due to the flow through the purge system the leak check portion of the diagnostic is complete The canister vent valve will unseal the system after completion of the test sequence as the pump diaphragm assembly moves to the full travel position Evaporative system functionality will be verified
21. events the diaphragm assembly from reaching full travel After the brief initialization period the solenoid is de energized allowing atmospheric pressure to enter the pump cavity This permits the spring to drive the diaphragm which forces air out of the pump cavity and into the vent system When the solenoid is ener gized and de energized the cycle is repeated creating flow in typical diaphragm pump fashion The pump is controlled in 2 modes PUMP MODE The pump is cycled at a fixed rate to achieve a rapid pressure build in order to shorten the overall test time TEST MODE The solenoid is energized with a fixed duration pulse Subsequent fixed pulses occur when the diaphragm reaches the switch closure point 25 14 EMISSION CONTROL SYSTEMS DESCRIPTION AND OPERATION Continued DUTY CYCLE PURGE SOLENOID DCPS DRIVER SWITCH SIGNAL INPUT ZJ POWERTRAIN CONTROL MODULE PCM TO THE PCM N M 3 PORT SOLENOID THROTTLE DRIVER BODY INTAKE MANIFOLD BERGE mir d TANK ROLLOVER VALVE amp fey VAPOR FLOW CONTROL ORIFICE COMBINED CANISTER n VENT VALVE SS oj amp Y SW LEAK DETECTION PUMP CANISTER 80004293 Fig 4 Evaporative System Monitor T The spring in the pump is set so that the system will achieve an equalized pressure of about 7 5 inches of water When the pump starts the cycle rate is quite high As the system becomes pressurized pump rate drops If there is no leak the pump will qu
22. ged connector pins However it might store diagnostic trouble codes as a result of spread connec tor pins HIGH AND LOW LIMITS The PCM compares input signal voltages from each input device with established high and low limits for the device If the input voltage is not within limits and other criteria are met the PCM stores a diagnos tic trouble code in memory Other diagnostic trouble code criteria might include engine RPM limits or input voltages from other sensors or switches that must be present before verifying a diagnostic trouble code condition ENGINE IDLE NEUTRAL 2500 RPM NEUTRAL All Engines 2 to 8 of Maximum Load 9 to 17 of Maximum Load 25 12 EMISSION CONTROL SYSTEMS ZJ EVAPORATIVE EMISSION CONTROLS INDEX page page DESCRIPTION AND OPERATION RANKCASE BREATHER FILTER 5 2L 5 9L RANKCASE VENTILATION CCV SYSTEM 4 OL ENGINE nuce cea a 14 DUTY CYCLE EVAP CANISTER PURGE SOLENOID idani trs ica eet ye dane DESCRIPTION AND OPERATION EVAPORATION CONTROL SYSTEM The evaporation control system prevents the emis sion of fuel tank vapors into the atmosphere When fuel evaporates in the fuel tank the vapors pass through vent hoses or tubes to a charcoal filled evap orative canister The canister temporarily holds the vapors The Powertrain Control Module PCM allows intake manifold vacuum to draw vapors into the com bustion chambers during certain operating condi tions All engines use a duty c
23. he Powertrain Control Module PCM have two recognized states HIGH and LOW For this reason the PCM cannot recognize the difference between a selected switch position versus an open cir cuit a short circuit or a defective switch If the State Display screen shows the change from HIGH to LOW or LOW to HIGH assume the entire switch circuit to the PCM functions properly Connect the DRB scan tool to the data link connector and access the state display screen Then access either State Display Inputs and Outputs or State Display Sensors CIRCUIT ACTUATION TEST MODE The Circuit Actuation Test Mode checks for proper operation of output circuits or devices the Powertrain Control Module PCM may not internally recognize The PCM attempts to activate these outputs and allow an observer to verify proper operation Most of the tests provide an audible or visual indication of device operation click of relay contacts fuel spray etc Except for intermittent conditions if a device functions properly during testing assume the device its associated wiring and driver circuit work cor rectly Connect the DRB scan tool to the data link connector and access the Actuators screen DIAGNOSTIC TROUBLE CODES A Diagnostic Trouble Code DTC indicates the PCM has recognized an abnormal condition in the system Diagnostic trouble codes are the results of a system or circuit failure but do not directly identify the failed component or components Tech
24. ing the O2S fault verify that the heater circuit is operating correctly Effective control of exhaust emissions is achieved by an oxygen feedback system The most important element of the feedback system is the O2S The O2S is located in the exhaust path Once it reaches oper ating temperature 300 to 350 C 572 to 662 F the sensor generates a voltage that is inversely propor tional to the amount of oxygen in the exhaust The information obtained by the sensor is used to calcu late the fuel injector pulse width This maintains a 14 7 to 1 Air Fuel A F ratio At this mixture ratio the catalyst works best to remove hydrocarbons HC carbon monoxide CO and nitrogen oxide NOx from the exhaust The voltage readings taken from the O2S sensor are very temperature sensitive The readings are not accurate below 300 C Heating of the O2S sensor is done to allow the engine controller to shift to closed loop control as soon as possible The heating element used to heat the O2S sensor must be tested to ensure that it is heating the sensor properly The O2S sensor circuit is monitored for a drop in voltage The sensor output is used to test the heater by isolating the effect of the heater element on the O2S sensor output voltage from the other effects LEAK DETECTION PUMP MONITOR IF EQUIPPED The leak detection assembly incorporates two pri mary functions it must detect a leak in the evapora tive system and seal the evaporative sy
25. ircuit between PCM and fuel gauge sending unit Circuit shorted to voltage between PCM and fuel gauge sending unit No movement of fuel level sender detected Battery temperature sensor input voltage below an acceptable range Battery temperature sensor input voltage above an acceptable range O2 sensor voltage too low tested after cold start O2 sensor voltage too low tested after cold start P1391 Intermittent Loss of CMP or CKP Intermittent loss of either camshaft or crankshaft position sensor A small leak has been detected by the leak detection monitor The leak detection monitor is unable to pressurize Evap system indicating a large leak Sump temp did not rise more than 16 F within 10 minutes when starting temp is below 40 F or sump temp is above 260 F with coolant below 100 F ZJ EMISSION CONTROL SYSTEMS 25 7 DESCRIPTION AND OPERATION Continued Generic Scan Tool A5 P0783 3 4 Shift Sol No RPM Drop 3 4 Shift The ratio of engine rpm output shaft speed did not change beyond on the minimum required A6 P0720 Low Ouput Spd Sensor RPM Above 15 Output shaft speed is less than 60 rpm with mph vehicle speed above 15 mph A7 Governor Pessure Sensor Volts Too Low Voltage less than 10 volts A8 Governor Pressure Sensor Volts Too HI Voltage greater than 4 89 volts A9 Governor Press Sen Offset Volts Too Lo Sensor input greater or less than calibration for or High 3 consecutive Neutral Park oc
26. it If there is a leak the test is terminated at the end of the test mode If there is no leak the purge monitor is run If the cyde rate increases due to the flow through the purge system the test is passed and the diagnostic is complete The canister vent valve will unseal the system after completion of the test sequence as the pump diaphragm assembly moves to the full travel position POSITIVE CRANKCASE VENTILATION PCV SYSTEM 5 2L 5 9L ENGINE The 5 2L 5 9L V 8 engine is equipped with a dosed crankcase ventilation system and a positive crank case ventilation PCV valve The 4 0L 6 coylinder engine is not equipped with a PCV valve Refer to Crankcase Ventilation System 4 0L Engine for information This system consists of a crankcase PCV valve mounted on the cylinder head valve cover with a hose extending from the valve to the intake manifold d ae eee WLY Wino e X i jn I A ED VY AUT rom ANINI y PCV VALVE HOSE CONNECTIONS _ _ J9214 35 Fig 5 PCV Valve Hose Typical A dosed engine crankcase breather filter with a hose connecting it to the air cleaner housing pro vides the source of air for system The PCV system operates by engine intake mani fold vacuum Fig 6 Filtered air is routed into the crankcase through the air cleaner hose and crank case breather filter The metered air along with crankcase vapors are drawn through the PCV valve and into a passage in the intake m
27. l by hand through the fitting to dislodge any solid particles Blow out the fitting with shop air If necessary use a smaller drill to avoid removing any metal from the fitting EMISSION CONTROL SYSTEMS 25 17 VACUUM SCHEMATICS A vacuum schematic for emission related items can be found on the Vehicle Emission Control Informa tion VECI Label Refer to VECI Label in this group for label location LEAK DETECTION PUMP LDP Refer to the appropriate Powertrain Diagnostic Procedures service manual for LDP testing proce dures REMOVAL AND INSTALLATION EVAPORATIVE EVAP CANISTER The EVAP canister is located in the left front cor ner of vehide below the left front headlamp Fig 16 MOUNTING NUTS 4 LEFT FRONT FENDER EVAP CANISTER 80a0c511 Fig 16 EVAP Canister Location REMOVAL 1 Remove the grill Refer to Group 23 Body 2 Remove the front bumper fascia assembly Refer to Group 23 Body 3 Disconnect vacuum lines at canister 4 Remove the canister mounting nuts 5 Lower the canister through bottom of vehicle INSTALLATION 1 Position canister to body 2 Install canister mounting nuts Tighten nuts to 9 N m 80 in Ibs torque 25 18 EMISSION CONTROL SYSTEMS REMOVAL AND INSTALLATION Continued 3 Connect vacuum lines Be sure vacuum lines are firmly connected and not leaking or damaged If leaking a Diagnostic Trouble Code DTC may be set with certain emission packages
28. lenoid 5 or 10 times per second depending upon operating condi tions The PCM varies the vapor flow rate by chang ing solenoid pulse width Pulse width is the amount of time that the solenoid is energized The PCM adjusts solenoid pulse width based on engine operat ing condition The solenoid attaches to a bracket located on the left inner fender Fig 3 LEAK DETECTION PUMP LDP The Leak Detection Pump LDP is used only with certain emission packages EMISSION CONTROL SYSTEMS 25 13 WINDSHIELD WASHER LEFT FRONT RESERVOIR BOTTLE FENDER ELECTRICAL CONNECTOR DUTY CYCLE EVAP CANISTER PURGE SOLENOID Ej FE EJ E E Fi FY BRACKET RS MOUNTING E3 NUTS 2 E SY 80a0c513 Fig 3 Duty Cycle EVAP Purge Solenoid Location Shown Without LDP The LDP is a device used to detect a leak in the evaporative system The pump contains a 3 port solenoid a pump that contains a switch a spring loaded canister vent valve seal 2 check valves and a spring diaphragm Immediately after a cold start engine temperature between 40 F and 86 F the 3 port solenoid is briefly energized This initializes the pump by drawing air into the pump cavity and also closes the vent seal During non test test conditions the vent seal is held open by the pump diaphragm assembly which pushes it open at the full travel position The vent seal will remain closed while the pump is cycling This is due to the operation of the 3 port solenoid which pr
29. ngine compartment below the EVAP canister purge solenoid Fig 18 The LDP and LDP filter are replaced serviced as one unit LEFT FRONT FENDER LEAK DETECTION PUMP LDP TEST PORT DUTY CYCLE EVAP CANISTER PURGE SOLENOID TO EVAP CANISTER LEAK DETECTION PUMP LDP VACUUM LINES 80a01309 Fig 18 Leak Detection Pump LDP Location REMOVAL 1 Remove air cleaner housing Refer to Group 14 Fuel System for procedures 2 Carefully remove all vapor vacuum lines at EVAP canister purge solenoid 3 Disconnect electrical connector at EVAP canis ter purge solenoid ZJ REMOVAL AND INSTALLATION Continued 4 Remove EVAP canister purge solenoid 5 Carefully remove hose at bottom of LDP filter 6 Disconnect electrical connector at LDP 7 Carefully remove vapor vacuum lines at LDP 8 Remove 2 LDP filter mounting bolts and remove filter 9 Remove LDP mounting bolts nuts 10 Remove LDP from vehicle INSTALLATION 1 Install LDP filter to mounting bracket Tighten bolts to 7 N m 65 in Ibs torque 2 Install LDP to mounting bracket Tighten bolts nuts to 7 N m 65 in Ibs torque 3 Carefully install vapor vacuum lines to LDP and LDP filter The vapor vacuum lines and hoses must be firmly connected Check the vapor vacuum lines at the LDP LDP filter and EVAP canister purge solenoid for damage or leaks If a leak is present a Diagnostic Trouble Code DTC may be set EMISSION CONTROL
30. nicians must retrieve stored DTC s by connect ing the DRB scan tool or an equivalent scan tool to the 16 way data link connector Fig 1 NOTE For a list of DTC s refer to the charts in this section OBTAINING DIAGNOSTIC TROUBLE CODES WARNING APPLY PARKING BRAKE AND OR BLOCK WHEELS BEFORE PERFORMING ANY TEST ON AN OPERATING ENGINE 1 Connect the DRB scan tool to data link diag nostic connector 2 Turn the ignition switch on access Read Fault Screen Record all the DTC s shown on the DRB scan tool 3 To erase DTC s use the Erase Trouble Code data screen on the DRB scan tool ZJ EMISSION CONTROL SYSTEMS 25 3 DESCRIPTION AND OPERATION Continued DIAGNOSTIC TROUBLE CODE DESCRIPTIONS Check EngineLamp MIL will illuminate during engine operation if this Diagnostic Trouble Code was recorded Generic Scan Tool Code DRB Scan Tool Display Description of Diagnostic Trouble Code DTC Error 01 P0340 No Cam Signal at PCM No camshaft signal detected during engine cranking 02 P0601 Internal Controller Failure POM Internal fault condition detected 05 P0162 Charging System Voltage Too Low Battery voltage sense input below target charging during engine operation Also no significant change detected in battery voltage during active test of generator output circuit P1594 Charging System Voltage Too High Battery voltage sense input above target charging voltage during engine operation 0A P1388 Auto Shutdown R
31. nsively on short run stop and go or extended engine idle service or extreme dust conditions AIR INLET FROM AIR CLEANER CYLINDER HEAD COVER MOUNTING NIPPLE 8925 28 Fig 11 Crankcase Breather Filter 5 2L 5 9L Engine VEHICLE EMISSION CONTROL INFORMATION VECI LABEL All vehicles are equipped with a combined VECI label This label is located in the engine compart ment Fig 12 and contains the following e Engine family and displacement e Evaporative family Emission control system schematic Certification application Engine timing specifications if adjustable Idle speeds if adjustable Spark plug and gap The label also contains an engine vacuum sche matic There are unique labels for vehicles built for sale in the state of California and the country of Canada Canadian labels are written in both the English and French languages These labels are per manently attached and cannot be removed without defacing information and destroying label J9325 2 VECI LABEL Fig 12 VECI Label Location Typical DIAGNOSIS AND TESTING PCV VALVE TEST 5 2L 5 9L ENGINE 1 With engine idling remove the PCV valve from cylinder head valve cover If the valve is not plugged a hissing noise will be heard as air passes through the valve Also a strong vacuum should be felt at the valve inlet Fig 13 PCV HOSE 7 PCV VALVE GROMMET ENGINE VALVE COVER VACUUM MUST BE FELT AGA
32. programmed memory acts as a self calibration tool that the engine controller uses to compensate for variations in engine specifications sensor tolerances and engine fatigue over the life span of the engine By monitoring the actual fuel air ratio with the O2S sensor short term and multiplying that with the program long term adaptive memory and comparing that to the limit it can be determined whether it will pass an emis sions test If a malfunction occurs such that the PCM cannot maintain the optimum A F ratio then the MIL will be illuminated CATALYST MONITOR To comply with dean air regulations vehides are equipped with catalytic converters These converters reduce the emission of hydrocarbons oxides of nitro gen and carbon monoxide Normal vehicle miles or engine misfire can cause a catalyst to decay A meltdown of the ceramic core can cause a reduction of the exhaust passage This can increase vehicle emissions and deteriorate engine performance driveability and fuel economy The catalyst monitor uses dual oxygen sensors O2S s to monitor the efficiency of the converter The dual O2S s sensor strategy is based on the fact that as a catalyst deteriorates its oxygen storage capacity and its efficiency are both reduced By monitoring the oxygen storage capacity of a catalyst its effi ciency can be indirectly calculated The upstream O2S is used to detect the amount of oxygen in the exhaust gas before the gas enters the cataly
33. short circuit checks or any component that has an associated limp in will set a fault after 1 trip with the malfunction present Components without an associated limp in will take two trips to illumi nate the MIL Refer to the Diagnostic Trouble Codes Description Charts in this section and the appropriate Power train Diagnostic Procedure Manual for diagnostic procedures NON MONITORED CIRCUITS The PCM does not monitor the following circuits systems and conditions that could have malfunctions causing driveability problems The PCM might not store diagnostic trouble codes for these conditions However problems with these systems may cause the PCM to store diagnostic trouble codes for other sys tems or components For example a fuel pressure problem will not register a fault directly but could cause a rich lean condition or misfire This could cause the PCM to store an oxygen sensor or misfire diagnostic trouble code FUEL PRESSURE The fuel pressure regulator controls fuel system pressure The PCM cannot detect a dogged fuel ZJ DESCRIPTION AND OPERATION Continued pump inlet filter clogged in line fuel filter or a pinched fuel supply or return line However these could result in a rich or lean condition causing the PCM to store an oxygen sensor or fuel system diag nostic trouble code SECONDARY IGNITION CIRCUIT The PCM cannot detect an inoperative ignition coil fouled or worn spark plugs ignition cross firing or open
34. stem so the leak detection test can be run The primary components within the assembly are A three port solenoid that activates both of the func tions listed above a pump which contains a switch two check valves and a spring diaphragm a canister vent valve CVV seal which contains a spring loaded vent seal valve Immediately after a cold start between predeter mined temperature thresholds limits the three port solenoid is briefly energized This initializes the pump by drawing air into the pump cavity and also closes the vent seal During non test conditions the vent seal is held open by the pump diaphragm assembly which pushes it open at the full travel posi tion The vent seal will remain closed while the pump is cycling due to the reed switch triggering of the three port solenoid that prevents the diaphragm assembly from reaching full travel After the brief ZJ DESCRIPTION AND OPERATION Continued initialization period the solenoid is deenergized allowing atmospheric pressure to enter the pump cavity thus permitting the spring to drive the dia phragm which forces air out of the pump cavity and into the vent system When the solenoid is energized and de energized the cycle is repeated creating flow in typical diaphragm pump fashion The pump is con trolled in 2 modes Pump Mode The pump is cycled at a fixed rate to achieve a rapid pressure build in order to shorten the overall test length Test Mode The solenoid is
35. though a malfunction has occurred This may happen because one of the DTC criteria for the circuit has not been met For example assume the diagnostic trouble code criteria requires the PCM to monitor the circuit only when the engine operates between 750 and 2000 RPM Suppose the sensor s output circuit shorts to ground when engine operates above 2400 RPM resulting in O volt input to the PCM Because the condition happens at an engine speed above the maximum threshold 2000 rpm the PCM will not store a DTC There are several operating conditions for which the PCM monitors and sets DTC s Refer to Moni tored Systems Components and Non Monitored Cir cuits in this section Technicians must retrieve stored DTC s by connect ing the DRB scan tool or an equivalent scan tool to the 16 way data link connector Fig 1 Refer to Diagnostic Trouble Codes in this section 25 2 EMISSION CONTROL SYSTEMS GENERAL INFORMATION Continued NOTE Various diagnostic procedures may actually cause a diagnostic monitor to set a DTC For instance pulling a spark plug wire to perform a spark test may set the misfire code When a repair is completed and verified connect the DRB scan tool to the 16 way data link connector to erase all DTC s and extinguish the MIL check engine lamp HEADLAMP SWITCH DATA LINK CONNECTOR LEFT SIDE OF COLUMN ABOVE BRAKE PEDAL 80a07536 Fig 1 Data Link Diagnostic Connector Location DESCRIPTION
36. tic con verter The PCM calculates the A F mixture from the output of the O2S A low voltage indicates high oxy gen content lean mixture A high voltage indicates a low content of oxygen rich mixture When the upstream O2S detects a lean condition there is an abundance of oxygen in the exhaust gas A functioning converter would store this oxygen so it can use it for the oxidation of HC and CO As the converter absorbs the oxygen there will be a lack of 25 10 EMISSION CONTROL SYSTEMS DESCRIPTION AND OPERATION Continued oxygen downstream of the converter The output of the downstream O2S will indicate limited activity in this condition As the converter loses the ability to store oxygen the condition can be detected from the behavior of the downstream O2S When the efficiency drops no chemical reaction takes place This means the con centration of oxygen will be the same downstream as upstream The output voltage of the downstream O2S copies the voltage of the upstream sensor The only difference is a time lag seen by the PCM between the switching of the O2S s To monitor the system the number of lean to rich switches of upstream and downstream O2S s is counted The ratio of downstream switches to upstream switches is used to determine whether the catalyst is operating properly An effective catalyst will have fewer downstream switches than it has upstream switches i e a ratio closer to zero For a totally ineffective c
37. wer than minimum required switching frequency Left Upstream O2S Heater Failure Upstream oxygen sensor heating element circuit malfunction Downstream Left Bank Downstream or Oxygen sensor heating element circuit Pre Catalyst Heater Failure malfunction Multiple Cylinder Mis fire Misfire detected in multiple cylinders Cylinder 1 Mis fire Misfire detected in cylinder 1 Cylinder 2 Mis fire Misfire detected in cylinder 2 Cylinder 3 Mis fire Misfire detected in cylinder 3 Cylinder 4 Mis fire Misfire detected in cylinder 4 P0420 Left Bank Catalytic or just Catalytic Catalyst efficiency below required level Efficency Failure P0441 Evap Purge Flow Monitor Failure Insufficient or excessive vapor flow detected during evaporative emission system operation 70 ici 71 72 P1899 P N Switch Stuck in Park or in Gear Incorrect input state detected for the Park Neutral switch auto trans only 76 P0172 Left Bank or Fuel System Rich A rich air fuel mixture has been indicated by an abnormally lean correction factor 77 P0171 Right Rear or just Fuel System Lean A lean air fuel mixture has been indicated by an abnormally rich correction factor 25 6 EMISSION CONTROL SYSTEMS DESCRIPTION AND OPERATION Continued Generic Scan Tool Code P0138 I y x Code DRB Scan Tool Display P1756 Governor Pressure Not Equal to Target 15 20 PSI or P1757 Governor Pressure Above 3 PSI In Gear With 0 MPH P0740
38. ycle purge system The PCM controls vapor flow by operating the duty cycle EVAP purge solenoid Refer to Duty Cycle EVAP Canister Purge Solenoid in this section When equipped with certain emissions packages a Leak Detection Pump LDP will be used as part of the evaporative system This pump is used as part of OBD II requirements Refer to Leak Detection Pump in this group for additional information NOTE The evaporative system uses specially man ufactured hoses If replacement becomes neces sary only use fuel resistant hose ROLLOVER VALVE The fuel tank is equipped with a rollover valve The valve is located on the top of the fuel tank Fig 1 The valve will prevent fuel flow through the fuel tank vent EVAP hoses in the event of an accidental vehicle rollover The EVAP canister draws fuel vapors from the fuel tank through this valve EHICLE EMISSION CONTROL INFORMATION VECI LABEL DIAGNOSIS AND TESTING EVAPORATIVE CANISTER PURGE SOLENOID FUEL pump FUEL SUPPLY MODULE TUBE iy ALIGNMENT ARROW EVAP ali Ne 12 O CLOCK VENT LINE y RETAINER arts ELECTRICAL PIGTAIL HARNESS FUEL FILTER FUEL PRESSURE REGULATOR ROLLOVER VALVE LOCKNUT Fig 1 Rollover Valve Location 80a61228 The valve cannot be serviced separately If replace ment is necessary the fuel tank must be replaced Refer to Fuel Tank removal and installation in this group EVAP
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