Volvo 850 Engine Troubleshooting With Codes
Contents
1. DIAGNOSTIC TEST MODE NO 3 under SELF DIAGNOSTICS If valve does not operate turn ignition on Connect voltmeter between valve connector terminal No 2 Green wire and ground If battery voltage is not present check wiring If battery voltage is present check voltage between connector terminals No 1 Blue Black wire and No 3 Blue White wire If voltage is not present check wiring 2 Connect voltmeter between ground and connector terminal No 1 Blue Black wire About 11 volts should be present Connect voltmeter between ground and connector terminal No 3 Blue White wire About 5 volts should be present If voltages are not as indicated check wiring for an open or short circuit If wiring is okay replace Idle Air Control IAC valve If voltages are correct or valve operates fault may be intermittent Check IAC valve signal 3 To check IAC valve signal connect measuring unit to fuel injection ECU Start engine Connect voltmeter between measuring unit terminals No 16 and 29 About 11 8 volts should be present with engine idling at operating temperature Connect voltmeter between measuring unit terminals No 17 and 29 About 7 volts should be present If voltage is not present as specified check wiring 4 To check voltage from IAC valve to fuel injection ECU turn ignition on Connect voltmeter between measuring unit terminals No 16 and 29 About 11 volts should be present Connect voltmeter between measuring unit terminals No2. If code is not displayed repeat test using new ignition ECU 4 If no electrical fault is found ensure carrier plate is not damaged or distorted This problem which applies primarily to A T vehicles can prevent engine from starting and set a code 1 4 3 Front Knock Sensor Signal Absent Or Faulty amp 4 3 3 Rear Knock Sensor Signal Absent Or Faulty Connect jumper wire between knock sensor connector terminals Connect measuring unit to ignition ECU See MEASURING UNIT under SELF DIAGNOSTIC SYSTEM Connect ohmmeter between measuring unit terminals No 22 and 23 or 24 and 25 depending on knock sensor being checked About zero ohms should be present If resistance is as specified replace knock sensor If resistance is not as specified check ignition ECU wiring 1 4 4 Load Signal From Fuel Injection System Absent Faulty 1 Check for codes in other systems by activating test mode No 1 See DIAGNOSTIC TEST MODE NO 1 under SELF DIAGNOSTICS Clear codes in ignition and fuel injection systems if present and test drive car 2 If code reoccurs connect measuring unit to ignition ECU See MEASURING UNIT under SELF DIAGNOSTIC SYSTEM Start engine Connect voltmeter between measuring unit terminals No 20 and 42 With engine idling at normal operating temperature approximately 50 millivolts should be present Voltage reading should increase with engine RPM If signal is present repeat diagnostic test using different ignition ECU 3
3. If signal is not present turn ignition off Connect ohmmeter between measuring unit terminals No 20 and 42 Infinite ohms should be present If zero ohms are present circuit is shorted to ground 4 Connect voltmeter between measuring unit terminals No 20 and 42 Turn ignition on If battery voltage is present circuit is shorted to voltage 5 If voltage readings are okay but signal is still not present measure resistance in circuit between ignition ECU terminal No 12 and fuel injection ECU terminal No 12 Pink wire If circuit is okay but signal is still not present repeat test using new fuel injection ECU Clear all codes in all other systems See DIAGNOSTIC TEST MODE NO 1 under SELF DIAGNOSTICS 1 5 4 EGR System Leakage 1 Symptom of EGR system leakage is rough idle Code will set when engine temperature is 150 F 65 C or less and temperature sensor detects an increasing temperature If ECU detects that temperature of EGR temperature sensor varies by more than a preset limit before temperature has reached 150 F 65 C ECU will interpret condition as an EGR flow and will initiate a code Some faults that can produce this code include Leaking EGR valve Signal to EGR controller faulty EGR controller defective Poor ground Engine thermostat defective 2 Start engine and listen to idle If idle is okay go to step 4 and check engine temperature If idle is not okay disconnect EGR controller connec
4. If speedometer signal is absent and Codes 1 3 1 instrument cluster and 3 1 1 fuel injection system are present wiring between instrument cluster cruise control and fuel injection and ignition systems is possibly open or shorted to ground or voltage 3 To check speed signal connect measuring unit to ignition ECU See MEASURING UNIT under SELF DIAGNOSTIC SYSTEM Raise and support front wheels of vehicle Turn ignition on Connect voltmeter between measuring unit terminals No 20 and 48 Spin front wheels Voltage should vary between 0 12 volts If voltage is consistently high or low check wiring for an open or short circuit If no fault is present replace ignition ECU 3 1 4 amp 3 2 4 Camshaft Position Sensor Signal Absent Faulty 1 Turn ignition off Connect measuring unit to ignition ECU See MEASURING UNIT under SELF DIAGNOSTIC SYSTEM Connect voltmeter between measuring unit terminals No 4 and 20 Operate starter motor Voltage should vary between 1 5 volts If voltage is incorrect take measurement directly at Camshaft Position CMP sensor 2 Turn ignition off If signal is still absent or faulty check CMP ground and supply by connecting an ohmmeter between measuring unit terminals No 15 and 20 About zero ohms should be present If reading is incorrect repeat test using new ignition ECU 3 To check CMP supply voltage connect voltmeter between measuring unit terminals No 14 and 20 Turn ignition on Approximately 1
5. go to next step 5 Turn ignition off Carefully disconnect Yellow vacuum hose at both ends Check Yellow vacuum hose for blockage If hose is okay repeat test using new EGR controller If hose is blocked repeat test using new vacuum hose 6 To check EGR valve turn ignition off Reconnect Yellow vacuum hose to EGR valve Connect vacuum pump to Yellow vacuum hose at EGR controller Start engine Increase vacuum to 9 in Hg 30 kPa Ensure EGR valve retains vacuum engine will run rough 7 If engine runs rough when vacuum pump shows vacuum but vacuum pump loses vacuum check Yellow vacuum hose for leakage If hose is okay retest using new EGR valve Clear codes If engine idles evenly when vacuum pump shows vacuum and vacuum pump maintains vacuum ensure EGR pipe is not blocked If pipe is not blocked repeat test using new EGR valve Clear codes 8 If engine idles rough when vacuum pump shows vacuum and vacuum pump maintains vacuum fault is intermittent Check vacuum controller connector If connector is okay check Green Brown wire between EGR controller terminal No 1 and ignition ECU terminal No 27 for intermittent short to voltage or ground 9 If EGR controller was not ticking in step 2 check voltage at EGR controller Turn ignition on Disconnect EGR controller connector Connect voltmeter between EGR controller connector terminal No 2 and ground See Fig 8 If voltmeter indicates battery voltage go to next step and check s
6. information Mass Airflow Sensor MAF Sensor Throttle Switch Engine Temperature Sensor Heated Oxygen Sensor HO2S A C Compressor Speedometer Automatic Transmission ECU Ignition ECU With Signals Indicating Engine Speed And Cooling Fan E FH OF Ignition System Diagnostics Ignition system ECU carries out continuous checks The following sensors and components supply ignition system ECU with information Injectors Idle Air Control IAC Valve Fuel Pump Main Fuel System Relay HO2S Heating Emission Warning Light ENTERING SELF DIAGNOSTICS FUEL INJECTION SYSTEM HF NOTE To perform diagnosis turn ignition on Ensure function selector cable is in diagnostic unit A socket No 2 See PAG Dee Diagnostic Test Mode No 1 On Board Diagnosis Press test button one time quickly on diagnostic unit A to display codes See Fig 1 ECU can store 3 faults at a time in diagnostic test mode No 1 Diagnostic trouble codes are stored when a faulty signal is detected Diagnostic Test Mode No 2 Function Testing Press test button 2 times to activate test mode No 2 LED should flash rapidly ECU should deliver an acknowledgment code when a signal is received from the following 3 3 2 Throttle switch when throttle leaves idling position 3 3 3 Throttle switch when throttle leaves full load position 1 1 4 Ignition system ECU when cooling fan is running 1 3 4 Low pressure switch
7. 17 and 29 About 5 volts should be present Turn ignition off 5 If no voltage was present check wiring between valve and ECU for an open circuit If voltage was present go to next step and check IAC valve coil resistance 6 Turn ignition off Connect ohmmeter between measuring unit terminals No 16 and 17 About 25 ohms should be present If resistance at measuring unit is incorrect check resistance at valve connector to determine if fault is in valve or wiring Replace valve or repair wiring as necessary 2 3 2 Adaptive HO2S Control Provides Richer Mixture At Idle 1 If Codes 2 1 2 or 1 1 3 are displayed go to step 8 and check HO2S sensor lead If Code 2 2 1 is displayed go to next step 2 Disconnect Mass Airflow MAF sensor connector Turn ignition on Connect voltmeter between MAF sensor connector terminal No 4 and ground See Fig 5 If voltmeter indicates about 2 7 volts go to next step If voltmeter does not indicate about 2 7 volts clean MAF sensor connector and measure voltage again If voltage is still incorrect repeat test using new MAF sensor Clear codes See CLEARING CODES 3 Disconnect HO2S female connector to ECU Turn ignition on Connect voltmeter between connector terminal No 2 and ground See Fig 6 If about zero volts are present check circuit between HO2S connector terminal No 2 and fuel injection ECU for an open circuit If voltmeter indicates more than 5 volts check circuit between HO2S connector
8. HO2S connector terminal No 1 and ground See Fig 4 If battery voltage is not present check wiring 93679166 Fig 4 Identifying HO2S Preheater Connector Terminals Courtesy of Volvo Cars of North America 4 If battery voltage is present connect voltmeter between measuring unit terminals No 28 and 20 Start engine Voltage should fall from battery voltage to approximately 4 volt Turn engine off If voltage reading does not fall to 4 volt repeat test using a known good ECU 5 Turn ignition off To check HO2S sensor preheat resistor connect ohmmeter between measuring unit terminals No 19 and 28 Depending on resistor temperature 3 13 ohms should be present If 3 13 ohms are not present use an ohmmeter and backprobe between terminals No 1 and 2 in HO2S 2 pin connector on firewall See Fig 4 6 If approximately 3 13 ohms are present check wire between fuel injection ECU and HO2S sensor for an open or short circuit If sensor reading is still incorrect replace HO2S sensor 7 To check HO2S sensor signal start engine Connect voltmeter between measuring unit terminals No 22 and 23 Voltage should vary between 1 9 volt after about 30 seconds If reading does not oscillate and voltage remains constant at 5 volt HO2S sensor wiring or connector is faulty 8 To check HO2S sensor signal at firewall connector disconnect HO2S connector at firewall Backprobe with voltmeter between connector terminal No 2 and ground If vol
9. If code is not recorded in fuel injection system or instrument panel go to step 4 3 Check for an open or short circuit between fuel injection and ignition system terminals No 53 Green Gray wire If wire is okay repeat test using new fuel injection ECU 4 If code is present in ignition system but not in fuel injection or instrument panel system check wire between fuel injection and ignition system terminals No 53 Green Gray wire for an open circuit If circuit is okay repeat diagnosis using new ignition ECU 1 3 1 VSS Signal Absent amp 2 1 4 VSS Signal Intermittent 1 Connect measuring unit to ignition ECU See MEASURING UNIT under SELF DIAGNOSTIC SYSTEM To check VSS signal connect voltmeter between measuring unit terminals No 1 and 2 Operate starter motor Voltmeter should indicate 300 400 millivolts with ignition switch in START position and about one volt with engine running 2 If voltage is not present turn ignition off Connect an ohmmeter between measuring unit terminals No 1 and 2 Resistance should be 200 400 ohms depending on temperature Connect ohmmeter between measuring unit terminals No 2 and 20 About zero ohms should be present 3 Disconnect Camshaft Position CMP sensor connector to prevent it from setting code Use diagnostic test mode No 2 and recheck sensor signal See DIAGNOSTIC TEST MODE NO 2 under SELF DIAGNOSTICS Operate starter motor Code 1 4 1 should be displayed vehicle speed sensor
10. terminal No 16 for an open circuit If ohmmeter shows more than 5 ohms disconnect ground wire located under intake manifold on engine block Clean and reconnect connector Clear codes 4 To check signal lead turn ignition on Disconnect EGR temperature sensor connector Connect voltmeter between EGR temperature sensor terminals No 1 and 2 See Fig 6 If voltmeter indicates about 5 volts go to step 6 and check EGR temperature sensor If voltmeter indicates about zero volts go to step 9 and check signal lead resistance 5 If voltmeter shows more than 5 volts check Green Yellow wire between EGR temperature sensor terminal No 1 and ignition ECU terminal No 5 for short to voltage In addition EGR temperature sensor can be faulty if signal lead has shorted to voltage For this testing go to next step 6 To check EGR temperature sensor turn ignition off Reconnect EGR temperature sensor connector Connect measuring unit to ignition ECU See MEASURING UNIT under SELF DIAGNOSTIC SYSTEM Disconnect ignition ECU Connect ohmmeter between measuring unit terminals No 5 and 6 If ohmmeter indicates about 2000 ohms at 68 F 20 C go to next step If infinite resistance is present repeat test using new EGR temperature sensor Clear codes 7 To check EGR temperature sensor signal reconnect ignition ECU and start engine Connect voltmeter between measuring unit terminals No 5 and 16 Voltmeter should indicate 1 8 4 6 volts depending on tem
11. terminal No 2 and fuel injection ECU for a short to voltage If voltmeter indicates about 2 volts go to next step 4 Turn ignition on Connect voltmeter between HO2S connector terminal No 1 and ground See Fig 6 If battery voltage is present go to next step If battery voltage is not present check circuit between HO2S connector No 1 and main relay No 3 See Figs 6 and 7 93179168 Fig 6 Identifying HO2S amp EGR Temperature Sensor Connector Terminals Courtesy of Volvo Cars of North America 93179169 Fig 7 Identifying Main Relay Connector Terminals Courtesy of Volvo Cars of North America 5 Turn ignition off Connect an ohmmeter between both male pins of HO2S connector If ohmmeter indicates about 3 13 ohms depending on temperature go to next step If ohmmeter does not indicate about 3 13 ohms retest system using a new oxygen sensor 6 Check for leakage at vacuum lines and connections See the M VACUUM DIAGRAMS article If vacuum leaks are found repair as necessary and clear codes If vacuum leakage is not found go to next step 7 Check fuel pressure See procedures under FUEL SYSTEM in the F BASIC TESTING article If fuel pressure is correct see test procedures under ELECTRONIC CONTROL UNIT FUEL INJECTION in the I SYSTEM COMPONENT TESTS article If fuel pressure is incorrect repair as necessary Clear codes if present 8 If Codes 2 1 2 or 1 1 3 were displayed in step 1 turn ignition on Disc
12. test using new MAF sensor 2 Check engine oil level and condition and adjust as necessary If oil level was incorrect or oil was contaminated clear codes If oil level and oil condition are okay check Fuel Evaporative EVAP system and repair as necessary See I SYSTEM COMPONENT TESTS article If EVAP system is okay check fuel pressure See FUEL SYSTEM in the C SPECIFICATIONS article If fuel pressure is incorrect repair as necessary and clear codes 3 If fuel pressure is correct check fuel injection ECU signals See ELECTRONIC CONTROL UNIT FUEL INJECTION in the I SYSTEM COMPONENT TESTS article Clear codes IGNITION SYSTEM DIAGNOSIS 1 1 2 ECU Fault Clear code Turn ignition on wait a few seconds then start engine Repeat this procedure several times If code resets replace ignition ECU If code does not reset check knock control circuit by driving vehicle at high load and speed above 3000 RPM If code returns replace ignition ECU 1 2 3 Engine Temperature Sensor Signal Absent Or Faulty 1 Activate diagnostic test mode No 1 and check if codes have been set by fuel injection socket No 2 and instrument panel socket No 7 systems See DIAGNOSTIC TEST MODE NO 1 under SELF DIAGNOSTICS If fuel injection Code 1 2 3 and instrument panel Codes 1 2 1 and 1 2 2 are displayed check fuel injection Code 1 2 3 2 If code is present in ignition system and instrument panel but not in fuel injection system go to next step
13. when A C compressor starts 1 2 4 AW50 42 A T ECU when gear selector lever is moved to or from a drive position 3 3 1 Ignition system ECU when transmitting speed signals Diagnostic Test Mode No 3 Control Testing Press test button 3 times to activate test mode No 3 ECU responds by activating components in following order Injectors at 12 Hz for 10 seconds 5 second pause IAC valve at one Hz for 10 seconds 5 second pause This sequence is repeated 3 times ENTERING SELF DIAGNOSTICS IGNITION SYSTEM NOTE To perform diagnosis turn ignition on Ensure function selector cable is in diagnostic unit A socket No 6 See Pigi 1 Diagnostic Test Mode No 1 On Board Diagnosis Press test button one time quickly on diagnostic unit A to display codes See Fig 1 ECU can record and store 13 faults at a ti me in diagnostic test mode No 1 Diagnostic trouble codes are stored when a faulty signal is detected Diagnostic Test Mode No 2 Function Testing Press test button 2 times to activate test mode No 2 LED should flash rapidly ECU should deliver an acknowledgment code when a signal is received from the following 1 VSS as flywheel rotates 2 CMP as camshaft rotates 3 Speedometer as front wheels rotate 4 Fuel injection ECU when throttle switch is operated by opening throttle Diagnostic Test Mode No 3 Control Testing Press test button 3 times to activate test mod
14. 0 volts should be present If voltage supply and ground connections are okay but signal is still not present take measurement at CMP connector If voltage supply and ground connections are okay but signal is still not present replace CMP 4 To check CMP signal in diagnostic test mode No 2 disconnect Vehicle Speed Sensor VSS connector to prevent it from displaying a trouble code Activate diagnostic test mode No 2 See DIAGNOSTIC TEST MODE NO 2 under SELF DIAGNOSTICS Start engine Code 3 4 2 should be displayed If code is not displayed repeat test using new ignition ECU 4 1 1 Throttle Switch Signal Absent Or Faulty 1 Activate fuel injection diagnostic test mode No 1 See DIAGNOSTIC TEST MODE NO 1 under SELF DIAGNOSTICS Check whether throttle switch code recorded If code recorded see 4 1 1 THROTTLE SWITCH SIGNAL ABSENT OR FAULTY under FUEL INJECTION DIAGNOSIS If fault is not in fuel injection system connect measuring unit to ignition ECU See MEASURING UNIT under SELF DIAGNOSTIC SYSTEM 2 Ensure ignition is off Connect ohmmeter between measuring unit terminals No 20 and 50 Very high or infinite resistance should be present A reading of zero ohms indicates a short to ground is present 3 Connect voltmeter between measuring unit terminals No 20 and 50 Turn ignition on If battery voltage is present circuit is shorted to voltage If resistance and voltage measurements are okay but signal is still absent turn igniti
15. A LED DOES NOT FLASH 1 Disconnect diagnostic unit A Turn ignition on Check for voltage at diagnostic connector terminal No 4 If voltage is not present check fuse and wiring If voltage is present turn ignition OFF 2 Connect an ohmmeter between diagnostic connector socket No 8 and ground Ohmmeter should indicate approximately zero ohms If reading is not approximately zero ohms check wiring If wiring is okay replace diagnostic unit A DIAGNOSTIC UNIT A LED FLASHES BUT ECU DOES NOT RESPOND 1 Turn ignition on Check for voltage at diagnostic socket No 2 fuel injection system or No 6 ignition system Approximately 10 volts should be present If approximately 10 volts is not present check wiring 2 Turn ignition off Connect Measuring Unit 9813190 See MEASURING UNIT Connect an ohmmeter between socket No 2 fuel injection system or No 6 ignition system and measuring unit terminal No 35 If continuity is present repeat test using a known good ECU CLEARING CODES 1 Turn ignition on Press test button for more than 5 seconds Release button LED should light after 3 seconds Press button again for more than 5 seconds Release button LED should go out 2 To ensure codes have been cleared press button for more than one second but no more than 3 seconds If Code 1 1 1 is displayed codes have been cleared If codes have not been cleared repeat procedure ECU LOCATION Fuel injection and ignition
16. E EDT TE Throttle Switch Signal Absent Or Faulty 1 HO2S Control Provides Leaner Mixture At Idle HO2S Integrator At Maximum Lean Running Limit OOBWNNNNNFPRBRPERP EE gt A PRERPWWNNEWWNHNEPEE 1 See FUEL INJECTION DIAGNOSIS under DIAGNOSTIC TROUBLE CODE TESTING for fault code diagnosis TROUBLE CODE DEFINITION IGNITION SYSTEM 1 Code Fault Repair cheat NEEE Raid he tee BAe NID Ses ie a eels eee wl No Faults se fate i ns SAS Repeal el I EENEN hele eo he este TEA Replace ECU Engine Temp Signal From Fuel Injection Absent Or Faulty E E A E E elo blsigo TEOR VSS Signal Absent EREA AER Front Knock Sensor Signal Absent Or Faulty Load Signal From Fuel Injection Absent Or Faulty A ERE OE EE RALLT ETT EGR System Leakage VSS Signal Intermittent M A eet A Sete EGR Flow Incorrect Speedometer Signal Absent Or Faulty Camshaft Position Sensor Signal Absent Or Faulty E EEEE E EIP T a EEA Camshaft Signal Intermittent ie Throttle Switch Signal From Fuel Injection Absent Or Faulty EEEE TE E EGR Temperature Sensor Signal Incorrect Missing SUS EEA e e e agave High Temperature Warning In ECU Box EE NA E Rear Knock Sensor Signal Absent Or Faulty PIPETES E E EEIE EA AE High Temperature Warning In ECU Box Oe SA RWWWNNPREREREE PWWREPNEPRPBPUDBRWNEE WWNHWEABPRP AR BRWREWNE 1 See IGNITION SYSTEM DIAGNOSIS under DIAGNOSTIC TROUBLE CODE TESTING for fault code diagnosis DIAGNOSTIC UNIT
17. G TESTS W CODES 1995 Volvo 850 1995 ENGINE PERFORMANCE Volvo Self Diagnostics 850 INTRODUCTION If no faults were found while performing procedures in the F BASIC TESTING article proceed with self diagnostics If no fault codes are present proceed to the H TESTS W O CODES article for diagnosis by symptom i e ROUGH IDLE NO START etc NOTE All voltage tests should be performed using a Digital Volt Ohmmeter DVOM with a minimum 10 megohm input impedance unless stated otherwise in testing procedures SELF DIAGNOSTIC SYSTEM RETRIEVING CODES CAUTION Self diagnostics for fuel injection and ignition systems are separate Use proper information for system being diagnosed Fuel Injection amp Ignition Systems Each system features a self diagnostic function for fault tracing Codes are retrieved using diagnostic unit A located in engine compartment in front of right strut tower Diagnostic unit A is equipped with an LED indicator activation button and function selector cable See Fig 1 NOTE Diagnostic unit B is not used for engine performance applications LED eer Indicator Activation Button Function Selector Cable 95A34470 Fig 1 Identifying Diagnostic Unit A Courtesy of Volvo Cars of North America Diagnostic unit A output socket No 2 is used for fuel injection diagnosis and socket No 6 is used for ignition system diagnosis Once function selector cable has been inser
18. ck CO connect CO meter to CO tap in exhaust pipe Start and run engine to operating temperature Disconnect HO2S connector Display record then erase codes Check CO 6 If meter indicates low CO and engine operates very unevenly engine is running lean See Codes 1 1 3 and 2 2 1 If meter indicates high CO greater than 2 5 percent engine is running rich and system must make mixture leaner to compensate for fuel leakage or other fault See Codes 2 3 1 and 5 1 2 7 If CO content is 3 2 5 percent and engine runs normally reconnect HO2S sensor and recheck CO content If reading becomes too high or low repeat test using new HO2S sensor If CO content is still incorrect repeat test using new fuel injection ECU 1 2 1 MAF Signal Absent Or Faulty 1 Connect measuring unit to fuel injection ECU See MEASURING UNIT under SELF DIAGNOSTIC SYSTEM To check Mass Airflow MAF sensor signal turn ignition on Connect voltmeter between measuring unit terminals No 13 and 20 About 2 7 volts should be present Start engine About 3 5 volts should be present at idle with engine hot Turn engine off If voltages are okay go to step 3 and check MAF sensor ground circuit If voltages are not okay go to next step 2 Turn ignition on Connect voltmeter between MAF sensor connector terminal No 4 and ground See Fig 5 Voltage should be about 2 7 volts Start engine Voltage should be about 3 5 volts during idle with engine hot If voltages are corre
19. ct check voltage supply for an open or short circuit If voltages are incorrect go to next step and check MAF sensor ground circuit 4321 93H79167 i Fig 5 Identifying MAF Sensor Connector Terminals Courtesy of Volvo Cars of North America 3 Turn ignition off Connect ohmmeter between MAF connector terminal No 2 and ground then between connector terminal No 1 and ground See Fig 5 Ohmmeter should indicate about zero ohms in both instances If reading is okay go to step 5 If reading is incorrect go to next step 4 Ensure ignition is off Connect ohmmeter between measuring unit terminals No 20 and 8 then between terminals No 20 and 12 Ohmmeter should indicate about zero ohms in both instances If reading is incorrect repeat test using new fuel injection ECU If reading is correct go to next step and check MAF sensor voltage supply 5 Turn ignition on Connect voltmeter between ground and MAF sensor connector terminal No 3 See Fig 5 Voltmeter should indicate battery voltage If voltage is not present check for an open or short circuit in voltage supply If voltage is present repeat test using new MAF sensor 1 2 3 Engine Temperature Sensor Signal Absent Or Faulty 1 Connect measuring unit to fuel injection ECU See MEASURING UNIT under SELF DIAGNOSTIC SYSTEM Turn ignition on Connect voltmeter between measuring unit terminals No 14 and 15 Voltmeter should indicate about 1 8 volts at 68 F 20 C and abo
20. e No 3 ECU responds by activating components in following order Cooling fan at half speed for 15 seconds Cooling fan at full speed for 15 seconds 15 second pause Variable flow intake manifold solenoid valve for 2 Hz for 5 seconds 5 second pause Speedometer for 5 seconds by generating a speed signal for approximately 1500 RPM 5 second pause The sequence is repeated 3 times DIAGNOSTIC TROUBLE CODE TESTING FUEL INJECTION DIAGNOSIS This section will cover codes dealing with fuel injection ECU testing Codes are followed by an explanation of how to test and repair affected circuit 1 1 2 Fuel Injection ECU Fault Turn ignition off Clear code See CLEARING CODES under SELF DIAGNOSTIC SYSTEM Turn ignition on and off 3 4 times Check for code If code is still present replace fuel injection ECU If code is not present system is okay 2 1 2 HO2S Signal Absent Or Faulty 1 To check HO2S sensor preheat resistor go to step 5 To check HO2S sensor signal go to step 7 To check voltage supply to HO2S sensor heating element go to next step 2 Connect measuring unit to fuel injection ECU See MEASURING UNIT under SELF DIAGNOSTIC SYSTEM Turn ignition on Connect voltmeter between measuring unit terminals No 20 and 28 If battery voltage is not present go to next step If battery voltage is present system is okay 3 Locate oxygen sensor 2 pin connector on firewall Use a voltmeter to backprobe between
21. f any exist in other systems Check diagnostic test mode No 1 to check for codes in A T and ignition system if code is displayed See DIAGNOSTIC TEST MODE NO 1 under SELF DIAGNOSTICS 1 3 2 Battery Voltage Too Low Or High Connect measuring unit to fuel injection ECU See MEASURING UNIT under SELF DIAGNOSTIC SYSTEM Connect voltmeter between measuring unit terminals No 10 and 20 Start engine and check voltmeter for battery voltage If voltage is too low or high check battery and charging system for malfunction 1 3 1 Ignition Speed System Signal Absent Or Faulty 1 Activate test mode No 2 See TEST MODE NO 2 under SELF DIAGNOSTICS Operate starter motor Code 3 3 1 should display If code is not present check speed signal from ignition system If code is present fault may be intermittent 2 Turn ignition off Connect measuring unit to fuel injection ECU See MEASURING UNIT under SELF DIAGNOSTIC SYSTEM Connect voltmeter between measuring unit terminals No 51 and 20 Operate starter motor Voltmeter should indicate 5 7 volts If voltage is not as specified check wiring between fuel injection and ignition ECUs In addition check output signal from ignition ECU 3 Turn ignition off Connect measuring unit to ignition ECU Connect voltmeter between measuring unit terminals No 51 and 20 Operate starter motor Voltmeter should indicate 5 7 volts If voltage is not as specified remove fuel injection ECU and repeat test If voltage
22. ignal lead If no voltage is present check for open circuit in Green wire between EGR controller terminal No 2 and main relay terminal No 3 Clear codes 93079170 Fig 8 Identifying EGR Controller Connector Terminals Courtesy of Volvo Cars of North America 10 To check signal lead turn ignition on Disconnect EGR controller connector Connect voltmeter between wiring side of EGR controller terminals No 1 and 2 See Fig 8 If battery voltage is not present check for open circuit or short to voltage in Green Brown wire between EGR controller terminal No 1 and ignition ECU terminal No 27 Clear codes If battery voltage is present go to next step 11 To check EGR controller resistance turn ignition off Disconnect EGR controller connector Connect an ohmmeter between EGR controller terminals See Fig 8 If ohmmeter shows 75 95 ohms at 68 F 20 C check EGR controller connections for oxidation Clear codes If ohmmeter does not show 75 95 ohms at 68 F 20 C repeat test using new EGR controller Clear codes 3 1 1 Speedometer Signal Absent Or Faulty 1 Test drive vehicle If speedometer does not operate fault is not in ignition system If speedometer operates during test drive instrument cluster is receiving input signal Activate diagnostic test mode No 1 for instrument cluster socket No 7 and fuel injection system socket No 2 See DIAGNOSTIC TEST MODE NO 1 under SELF DIAGNOSTICS Display codes if present 2
23. is still not present repeat test with new ignition ECU 3 1 1 Speedometer Signal Absent Or Faulty 1 Test drive vehicle If speedometer does not operate fault is not in fuel system If speedometer operates during test drive instrument cluster is receiving input signal Activate diagnostic test mode No 1 for instrument panel socket No 7 and ignition system socket No 6 Display codes if present 2 If speedometer signal is absent and Codes 1 3 1 instrument cluster and 3 1 1 ignition system are present wiring between instrument cluster cruise control and fuel injection and ignition systems is possibly open or shorted to ground or voltage 3 To check speed signal connect measuring unit to fuel injection ECU See MEASURING UNIT under SELF DIAGNOSTIC SYSTEM Raise and support vehicle so front wheels are off ground Turn ignition on Connect voltmeter between measuring unit terminals No 20 and 48 Spin front wheels Voltage should vary between 0 12 volts If voltage is consistently high or low check wiring for an open or short circuit If no fault is present replace fuel injection ECU 5 1 1 Adaptive HO2S Control Provides Leaner Mixture At Idle 1 Turn ignition on Connect voltmeter between Mass Airflow MAF sensor connector terminal No 4 and ground See Fig 5 If voltmeter indicates about 2 7 volts go to next step If voltage is not to specification clean MAF sensor connector and repeat test If still incorrect repeat
24. mptom i e ROUGH IDLE NO START etc or intermittent diagnostic procedures
25. on If codes are not displayed check throttle switch wiring supply and resistance If codes are displayed fault may be intermittent Check signal supply and ground 3 Connect measuring unit to fuel injection ECU SEE MEASURING UNIT under SELF DIAGNOSTIC SYSTEM Turn ignition on Connect voltmeter between measuring unit terminals No 1 and 14 At idle position about 6 volt should be present In full load position about 4 2 volts should be present If voltage is not present or to specification connect voltmeter between measuring unit terminals No 2 and 20 Voltmeter should indicate 5 volts 4 Turn ignition off Connect ohmmeter between measuring unit terminals No 14 and 20 Ohmmeter should indicate about zero ohms If voltage was not present or ground connection was faulty check wiring for short to ground or voltage If wiring is okay repeat test using new fuel injection ECU If voltage is present and resistance check shows ground is okay go to next step 5 Check throttle switch resistance by connecting ohmmeter between measuring unit terminals No 14 and 2 About 1800 2200 ohms should be present Measure resistance between measuring unit terminals No 14 and 1 Resistance should be about 1000 ohms at idle and 2600 ohms at full load 6 If resistances are not to specification take resistance measurements at throttle switch connector to determine whether fault is in switch or wiring If switch is faulty replace switch Clear codes i
26. on off 4 Use an ohmmeter and check continuity between ignition and fuel injection ECU terminals No 20 Green Brown wire If circuit is okay but signal is still not present repeat test using a known good fuel injection ECU Clear codes if any exist in other systems Check diagnostic test mode No 1 to check for codes in A T and ignition system if code is displayed See DIAGNOSTIC TEST MODE NO 1 under SELF DIAGNOSTICS 4 1 3 EGR Temperature Sensor Signal Incorrect Missing 1 ECU uses EGR temperature sensor signal to determine whether an EGR flow is present A code will set if signal from sensor to ECU is too high too low or incorrect Following fault sources can cause an incorrect or missing EGR temperature sensor Faulty EGR temperature sensor open or short circuit Signal lead short circuit Signal lead short circuit to ground Ground lead open circuit OF Signal lead short circuit to another lead Loose contact at EGR temperature sensor connector Tracking current at EGR temperature sensor connector 2 Turn ignition off Disconnect EGR temperature sensor Check and clean EGR temperature sensor connector Connect ohmmeter between wiring side of temperature sensor connector terminal No 2 and ground 3 If ohmmeter indicates about zero ohms go to next step and check signal lead If ohmmeter shows infinite resistance check Green Black wire between temperature sensor connector terminal No 2 and ignition ECU
27. onnect HO2S male connector at ECU Connect voltmeter between connector terminals No 1 and 2 See Fig 6 Voltmeter should indicate approximately 4 5 volt If voltage is to specification go to next step If voltage is not to specification reconnect connector and go to step 10 9 Reconnect HO2S connector Start engine and run to normal operating temperature Connect voltmeter between HO2S connectors No 1 and 2 See Fig 6 Voltmeter should indicate 1 9 volt If voltage is not present repeat test using new HO2S sensor Clear codes If voltage is present fault is intermittent Check HO2S connector for damage or poor connection Clear codes 10 If voltage was not to specification in step 8 turn ignition off Disconnect fuel injection ECU Connect an ohmmeter between connector terminals No 1 and 2 If ohmmeter indicates infinite resistance check Green Black wire between connector terminal No 2 and ECU pin No 22 for an open circuit If ohmmeter does not indicate infinite resistance check Green Black wire between connector terminal No 2 and ECU pin No 22 for a short to ground Clear codes 4 1 1 Throttle Switch Signal Absent Or Faulty 1 Activate diagnostic test mode No 2 See DIAGNOSTIC TEST MODE NO 2 under SELF DIAGNOSTICS Turn throttle slightly If Code 3 3 2 is displayed switch function is okay in idling position 2 Turn throttle to WOT and release If Code 3 3 3 is displayed switch function is okay in wide open positi
28. perature voltage drops as temperature rises 8 Disconnect Yellow vacuum line from EGR controller Connect vacuum pump to hose facing EGR valve Increase vacuum Engine should idle rough If voltage drops slowly as temperature rises temperature sensor is okay Check EGR temperature sensor connector for poor connection Clear codes If voltage does not drop as temperature rises retest using new EGR temperature sensor 9 If voltmeter indicated about zero volts in step 4 check resistance of signal lead to ground Turn ignition off Disconnect ignition ECU Connect ohmmeter between EGR temperature sensor terminals No 1 and 2 See Fig 6 If ohmmeter indicates infinite resistance check Green Yellow wire between EGR temperature sensor terminal No 1 and ignition ECU terminal No 5 for an open circuit If ohmmeter does not indicate infinite resistance check Green Yellow wire for a short to ground In both instances clear codes 4 3 2 amp 5 1 3 High Temperature Warning In ECU Box Code 4 3 2 is recorded if temperature in ECU box exceeds 185 F 85 C for more than 18 seconds Code 5 1 3 is recorded if temperature continues to rise and exceeds 203 F 95 C for more than 18 seconds If this problem is persistent install accessory fan kit in ECU holder SUMMARY If no hard fault codes or only pass codes are present driveability symptoms exist or intermittent codes exist proceed to the H TESTS W O CODES article for diagnosis by sy
29. system ECUs are located in right front of engine compartment in front of strut tower MEASURING UNIT Connecting Measuring Unit 9813190 amp Adapter 9813195 1 Disconnect negative battery cable Remove ECU cover located in right front engine compartment See Fig 2 If measuring unit is to be connected to fuel injection ECU remove both fuel injection and ignition ECUs Press adapter into ECU base Position adapter lead at rear of ECUs and thread through slot next to ignition ECU Far cn sou sman Fig 2 Locating Electronic Control Units Courtesy of Volvo Cars of North America 2 Press ignition ECU into position first to avoid damage to adapter lead Press fuel injection ECU with adapter connected into connector in bottom of ECU box Connect measuring unit to adapter 60 pin connector 3 If measuring unit is to be connected to ignition ECU remove ignition ECU Press adapter onto ignition ECU and pull lead upward through slot beside ECU Press ignition ECU with adapter connected into connector in bottom of ECU box Connect measuring unit to adapter 60 pin connector See Fig 3 ECU 60 Pin Connector Measuring Unit ECU 93F79165 Fig 3 Installing Measuring Unit amp Adapter Courtesy of Volvo Cars of North America SELF DIAGNOSTICS Fuel Injection System Diagnostics Fuel injection ECU carries out continuous checks The following sensors and components supply fuel injection system ECU with
30. tage reading oscillates check wiring between fuel injection ECU and HO2S sensor for an open or short circuit If voltage reading remains constant at 5 volt repeat test using new HO2S sensor 1 1 3 HO2S Integrator At Maximum Enrichment Limit 2 2 1 Adaptive HO2S Control Rich At Part Load 2 3 1 Adaptive HO2S Control Lean At Part Load amp 5 1 2 HO2S Integrator At Maximum Lean Running Limit 1 Code 1 1 3 or 2 2 1 means that engine is running lean This may be caused by an air leak or an HO2S sensor fault Code 2 3 1 or 5 1 2 means that engine is running rich This may be caused by high fuel pressure leaking injector s faulty MAF signal or faulty HO2S sensor 2 Connect measuring unit to fuel injection ECU See MEASURING UNIT under SELF DIAGNOSTIC SYSTEM To check HO2S sensor signal start engine Connect voltmeter between measuring unit terminals No 22 and 23 Voltage should vary between 1 9 volt after about 30 seconds 3 If voltmeter indicates a constant one or zero volts HO2S sensor is interpreting lean air fuel ratio or is shorted to ground Disconnect HO2S sensor connector at firewall Use a voltmeter and backprobe between connector terminal No 2 and ground See Fig 4 4 If voltage remains constant at zero or one volt check engine CO adjustment If voltage varies between 1 9 volt and code is still present HO2S control is adjusting CO correctly but fuel injection ECU is indicating fault Check engine CO 5 To che
31. ted in correct socket depress button and keep depressed for more than one second but not more than 3 seconds Observe LED and count number of flashes to determine diagnostic trouble code as faults stored in Electronic Control Unit ECU memory are read by observing LED flashes If LED does not flash see DIAGNOSTIC UNIT A LED DOES NOT FLASH Diagnostic systems for fuel injection and ignition each store 13 codes All codes contain 3 digits example 4 1 3 Since all codes have 3 digits each code requires 3 series of flashes A 3 second interval separates each series of flashes See the appropriate TROUBLE CODE DEFINITION table TROUBLE CODE IDENTIFICATION TROUBLE CODE DEFINITION FUEL INJECTION SYSTEM 1 Code Fault Repair TETTES E TEEPEE EEEIEE ETTEREN es ite eG Spe eee No Fault was Oh af shear ey ENNE OE isos Sys Replace ECU HO2S Integrator At Maximum Enrichment ou ghioabubigeiteltelteltevietausiie E E TEE S T ane MAF Sensor Signal Absent Or Faulty og Engine Temperature Sensor Signal Absent Or Faulty EREE EEE Ignition System Speed Signal Absent Or Faulty Battery Voltage Too High Or Too Low HO2S Sensor Signal Absent Or Faulty Adaptive HO2S Control Engine Running Too Rich At Part Load A E ote sphere E EE N IAC Valve Signal Absent Or Faulty Adaptive HO2S Control Engine Running Too Lean At Part Load Adaptive HO2S Control Provides Richer Mixture At Idle 1 os c EEEN Speedometer Signal Absent Or Faulty iL PARE E
32. tor If idle is still rough go to next step and check EGR controller If idle is now okay check Green Brown wire between ignition ECU terminal for a short to ground 3 To check EGR controller run engine at idle Carefully disconnect Yellow hose from EGR controller If idle is now okay repeat test using new EGR controller If idle is still rough turn ignition off Carefully disconnect Yellow hose from EGR valve Check hose for blockage or leaks If Yellow hose is okay repeat test using new EGR valve If hose is blocked or leaking replace hose In both cases clear codes 4 Check engine temperature gauge with engine running If gauge pointer does not rise to normal and top radiator hose is hot go to next step If gauge shows normal operating temperature and top radiator hose is hot go to step 6 If gauge pointer rises slowly and top radiator hose is not at normal operating temperature retest system using new thermostat Clear codes 5 Turn ignition off Disconnect Mass Airflow MAF sensor connector Connect an ohmmeter between MAF sensor connector terminal No 2 and ground See Fig 5 If ohmmeter indicates about zero ohms go to next step If ohmmeter does not indicate about zero ohms disconnect electrical connector located under intake manifold on engine block Clean and reconnect connector Clear codes 6 Code may be set by contact resistance at EGR and engine temperature sensor connector Clean and protect EGR and engine tempera
33. ture sensor connectors from oxidation dirt etc Clear codes 2 4 1 EGR Flow Incorrect 1 EGR temperature sensor signal should change when signal from ECU is sent to vacuum controller If signal does not change ECU registers a fault and sets code Possible faults include Break in signal lead No voltage at EGR controller Faulty EGR controller Poor vacuum supply to EGR valve White vacuum hose Faulty Yellow vacuum hose EGR valve does not open HF 2 To check operation of EGR vacuum controller start and run engine so it reaches normal operating temperature Put hand on EGR controller and increase engine speed several times over 2000 RPM If EGR controller produces a ticking sound go to next step If EGR controller is not ticking go to step 9 and check voltage supply to EGR controller 3 Ensure engine is still running Carefully disconnect White vacuum hose from EGR controller and check for vacuum If vacuum is not present check White vacuum hose between controller and intake manifold If vacuum is present go to next step and check vacuum from EGR controller 4 Turn ignition off Reconnect White vacuum hose to EGR controller Carefully disconnect Yellow vacuum hose from EGR controller Connect vacuum gauge to EGR controller Start engine Increase engine speed repeatedly If gauge pointer moves rapidly verifying EGR controller is passing vacuum go to step 6 and check EGR valve If gauge does not move rapidly
34. ut 250 millivolts when engine is at operating temperature 2 If voltage is not to specification check output voltage from fuel injection ECU Disconnect temperature sensor connector Turn ignition on Connect voltmeter between measuring unit terminals No 14 and 15 About 5 volts should be present 3 If voltage is not to specification check circuit between temperature sensor and ECU for an open or short circuit If circuit is okay repeat test using new ECU If circuit is not okay go to next step 4 Ensure ignition is off Repair circuit between temperature sensor and ECU ensuring sensor terminal No 14 is grounded Connect ohmmeter between measuring unit terminals No 20 and 14 Ohmmeter should indicate about zero ohms If resistance is not to specification repeat test using new fuel injection ECU 5 If resistance is to specification check resistance between measuring unit terminals No 14 and 15 See TEMPERATURE SENSOR RESISTANCE SPECIFICATIONS table If resistances are not to specification replace sensor or repair wiring as necessary Clear any codes in other systems TEMPERATURE SENSOR RESISTANCE SPECIFICATIONS TABLE Temperature F C Ohms 68 20 etewee ne eee te eee Rein C64 ope ee eS 2800 TAO COO eee rgd noo NOS EEEE EEEE AAA 4 Be Pete Ser Y 560 MOA COON cei tatetetes te BaP DAR OaE ARAE E eet te te ee EL 206 2 2 3 IAC Valve Signal Absent Or Faulty 1 Check operation of idle valve in test mode No 3 See
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