Home ReviewsRefund
Home/Pontiac/Sunfire/Pontiac Sunfire I (1995-2005)/Repair manual/Testing & Diagnostics/Engine Controls - Basic Diagnostic Procedures - 2.2L: Overv…
Contents Wiring diagrams Section: Testing & Diagnostics All sections

Engine Controls - Basic Diagnostic Procedures - 2.2L: Overview Pontiac Sunfire I

Testing & Diagnostics 3 illustrations ~7391 words

MODEL IDENTIFICATION

Body Code (1)Model
"J"(2) Cavalier & Sunfire
"N"Alero & Grand Am
(1) Vehicle body code is fourth character of VIN. (2) Cavalier is also available with 2.2L Bi-Fuel - CNG/Gasoline engine.
(1)Vehicle body code is fourth character of VIN.
(2)Cavalier is also available with 2.2L Bi-Fuel - CNG/Gasoline engine.

MODEL IDENTIFICATION

Description

The Engine Cranks but Does Not Run diagnostic table is an organized approach to identifying a condition that causes an engine not to start. The Engine Cranks but Does Not Run diagnostic table directs the service technician to the appropriate system diagnosis. The Engine Cranks but Does Not Run diagnostic table assumes the following

  1. The battery is completely charged.
  2. The engine cranking speed is acceptable.
  3. There is adequate fuel in the fuel tank.

Test Description

The number below refers to the step number in the diagnostic procedure.

  1. 5 - While cranking the engine, the Crankshaft Position (CKP) activity should increment to 255, then rollover to zero.
  1. Did you perform the Diagnostic System Check - Engine Controls? If yes, go to next step. If no, go to «DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS»(ref-153397-S21035650842003040400000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS - 2.2L ALERO, CAVALIER, GRAND AM & SUNFIRE - GASOLINE article.
  2. Turn ignition switch to RUN position, engine OFF. Observe the DTC Information using a scan tool. Does the scan tool display DTCs P0336, P0601, P0602, P1621, P1631, or P1632? If yes, go to «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(ref-153397-S21975802792003040400000) in SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS - 2.2L ALERO, CAVALIER, GRAND AM & SUNFIRE - GASOLINE article. If no, go to next step.
  3. Does the scan tool display any Body Control Module (BCM) or Vehicle Theft Deterrent (VTD) DTCs? If yes, go to «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(ref-153397-S21975802792003040400000) in SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS - 2.2L ALERO, CAVALIER, GRAND AM & SUNFIRE - GASOLINE article. If no, go to next step.
  4. Monitor the ignition 1 signal parameter using a scan tool. Is the ignition 1 signal parameter at battery voltage? If yes, go to next step. If no, go to step 11.
  5. Attempt to start the engine. Monitor the CKP activity counter while the engine is cranking, using a scan tool. Does the CKP activity counter increment while cranking the engine? If yes, go to next step. If no, go to «ELECTRONIC IGNITION SYSTEM DIAGNOSIS»(ref-153404-S34622258352003051300000) under IGNITION SYSTEMS in SYSTEM & COMPONENT TESTING - 2.2L ALERO, CAVALIER, GRAND AM & SUNFIRE article.
  6. Using a scan tool, command the fuel pump ON. Does the fuel pump operate? If yes, go to next step. If no, go to «FUEL PUMP ELECTRICAL CIRCUIT DIAGNOSIS»(ref-153404-S22833539312003050500000) under FUEL SYSTEMS (GASOLINE) in SYSTEM & COMPONENT TESTING - 2.2L ALERO, CAVALIER, GRAND AM & SUNFIRE article.
  7. Turn ignition switch to OFF position. Remove the ignition coil housing. Install a jumper wire with clips on both ends from the top of the Ignition Control Module (ICM) to ground. Install the Ignition System Diagnostic Harness (J 36012-A), or equivalent. Install Spark Tester (J 26792), or equivalent, on No. 1 spark plug jumper wire. Ground No. 4 (companion to No. 1) spark plug jumper wire. Crank the engine with the remaining spark plug jumper wires connected. Repeat the above steps by installing the spark tester on No. 4 and grounding No. 1. Do the same for No. 2 and No. 3 spark plugs. Ensure the companion wire is grounded. Does the spark tester spark on all cylinders? If yes, go to next step. If no, go to «ELECTRONIC IGNITION SYSTEM DIAGNOSIS»(ref-153404-S34622258352003051300000) under IGNITION SYSTEMS in SYSTEM & COMPONENT TESTING - 2.2L ALERO, CAVALIER, GRAND AM & SUNFIRE article.
  8. Turn ignition switch to OFF position. Disconnect an injector harness connector. Install Injector Test Light (J 34730-405), or equivalent, to the injector connector. Attempt to start the engine. Does the test light blink while the engine is cranking? If yes, go to next step. If no, go to «FUEL INJECTOR CIRCUIT DIAGNOSIS»(ref-153404-S42215340582003051300000) under FUEL SYSTEMS (GASOLINE) in SYSTEM & COMPONENT TESTING - 2.2L ALERO, CAVALIER, GRAND AM & SUNFIRE article.
  9. Turn ignition switch to OFF position. Connect Fuel Pressure Gauge (J 34730-1A), or equivalent, to the fuel pressure connection, located on the fuel rail. (Scheme 73) Turn ignition switch to RUN position, engine OFF. Command the fuel pump ON using a scan tool. Is the fuel pressure 50-60 psi (345-414 kPa) while the fuel pump is operating? If yes, go to next step. If no, go to «FUEL SYSTEM DIAGNOSIS (GASOLINE)»(ref-153407-S03416773192003120300000) or «FUEL SYSTEM DIAGNOSIS (CNG)»(ref-153407-S34718758222003120300000).
  10. Check for the following conditions: Collapsed air intake duct. Restricted air filter element. Check spark plugs for gas or coolant fouling. If the spark plugs are fouled, determine what caused the condition. Engine mechanical condition; worn timing chain and gears, low compression. Restricted exhaust system. Go to «RESTRICTED EXHAUST»(ref-153405-S10795551862003051300000) under SYMPTOMS in TROUBLE SHOOTING - 2.2L ALERO, CAVALIER, GRAND AM & SUNFIRE - GASOLINE article. The Engine Coolant Temperature (ECT) sensor is NOT close to the actual engine temperature. Go to «DTC P0117: ENGINE COOLANT TEMPERATURE SENSOR»(ref-153397-S30232025122003040400000) or «DTC P0118: ENGINE COOLANT TEMPERATURE SENSOR»(ref-153397-S02548921182003040400000) under DIAGNOSTIC TESTS in SELF-DIAGNOSTICS - 2.2L ALERO, CAVALIER, GRAND AM & SUNFIRE - GASOLINE article. Compare Manifold Absolute Pressure/Throttle Position (MAP/TP) parameters to another vehicle. The parameters should be close in value. Go to «DTC P0105: MANIFOLD ABSOLUTE PRESSURE SENSOR»(ref-153397-S36390896992003040400000) under DIAGNOSTIC TESTS in SELF-DIAGNOSTICS - 2.2L ALERO, CAVALIER, GRAND AM & SUNFIRE article. Did you complete the action? If yes, go to step 14.
  11. Test the ignition 1 signal voltage circuit supplied by the PCM IGN fuse for an open or for a short to ground. Replace the fuse if necessary. Did you find and correct the condition? If yes, go to step 14. If no, go to next step.
  12. Check for poor connections at the PCM harness connector. Did you find and correct the condition? If yes, go to step 14. If no, go to next step.
  13. Replace PCM. See POWERTRAIN CONTROL MODULE under COMPUTERIZED ENGINE CONTROLS in appropriate REMOVAL & INSTALLATION article. Program PCM with correct vehicle software and calibration. See «PROGRAMMING»(ref-153397-S04126431652003040400000) in SELF-DIAGNOSTICS - 2.2L ALERO, CAVALIER, GRAND AM & SUNFIRE - GASOLINE article. After repair, go to next step.
  14. Using the scan tool, clear the DTCs. Turn ignition switch to OFF position for 30 seconds. Attempt to start the engine. Does the engine start then continue to run? If yes, go to next step. If no, go to step 2.
  15. Allow the engine to reach operating temperature. Observe the DTC information using a scan tool. Are there any DTCs that have not been diagnosed? If yes, go to «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(ref-153397-S21975802792003040400000) under SELF-DIAGNOSTICS in SELF-DIAGNOSTICS - 2.2L ALERO, CAVALIER, GRAND AM & SUNFIRE - GASOLINE article. If no, system is okay at this time.

The Engine Cranks but Does Not Run diagnostic table is an organized approach to identifying a condition that causes an engine not to start. The Engine Cranks but Does Not Run diagnostic table directs the service technician to the appropriate system diagnosis. This diagnostic procedure assumes the following

  1. The battery is completely charged.
  2. The engine cranking speed is acceptable.
  3. There is adequate fuel in the fuel tank.

The number below refers to the step number in the diagnostic procedures.

  1. 4 - While cranking the engine, the Crankshaft Position (CKP) activity should increment to 255, then rollover to zero.
  1. Did you perform the Diagnostic System Check - Engine Controls? If yes, go to next step. If no, go to «DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS»(ref-153397-S21035650842003040400000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS - 2.2L ALERO, CAVALIER, GRAND AM & SUNFIRE - GASOLINE article.
  2. Turn ignition switch to RUN position, engine OFF. Observe the DTC Information using a scan tool. Does the scan tool display DTCs P0336, P0601, P0602, P1621, P1631, or P1632? If yes, go to «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(ref-153397-S21975802792003040400000) in SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS - 2.2L ALERO, CAVALIER, GRAND AM & SUNFIRE - GASOLINE article. If no, go to next step.
  3. Does the scan tool display any Body Control Module (BCM) Vehicle Theft Deterrent (VTD) DTCs? If yes, go to «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(ref-153397-S21975802792003040400000) in SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS - 2.2L ALERO, CAVALIER, GRAND AM & SUNFIRE - GASOLINE article. If no, go to next step.
  4. Attempt to start the engine. Monitor the CKP activity counter while the engine is cranking with a scan tool. Does the CKP activity counter increment while cranking the engine? If yes, go to next step. If no, go to «ELECTRONIC IGNITION SYSTEM DIAGNOSIS»(ref-153404-S34622258352003051300000) under IGNITION SYSTEMS in SYSTEM & COMPONENT TESTING - 2.2L ALERO, CAVALIER, GRAND AM & SUNFIRE article.
  5. Using a scan tool, command the fuel pump ON. Does the fuel pump operate? If yes, go to next step. If no, go to «FUEL INJECTOR CIRCUIT DIAGNOSIS»(ref-153404-S42215340582003051300000) under FUEL SYSTEMS in SYSTEM & COMPONENT TESTING - 2.2L ALERO, CAVALIER, GRAND AM & SUNFIRE article.
  6. Turn ignition switch to OFF position. Remove the ignition coil housing. Install a jumper wire with clips on both ends from the top of the Ignition Control Module (ICM) to ground. Install the Ignition System Diagnostic Harness (J 36012-A), or equivalent. Install Spark Tester (J 26792), or equivalent, on No. 1 spark plug jumper wire. Ground No. 4 (companion to No. 1) spark plug jumper wire. Crank the engine with the remaining spark plug jumper wires connected. Repeat the above steps by installing the spark tester on No. 4 and grounding No. 1. Do the same for No. 2 and No. 3 spark plugs. Ensure the companion wire is grounded. Does the spark tester spark on all cylinders? If yes, go to next step. If no, go to «ELECTRONIC IGNITION SYSTEM DIAGNOSIS»(ref-153404-S34622258352003051300000) under IGNITION SYSTEMS in SYSTEM & COMPONENT TESTING - 2.2L ALERO, CAVALIER, GRAND AM & SUNFIRE article.
  7. Turn ignition switch to OFF position. Disconnect an injector harness connector. Install Injector Test Light (J 34730-405), or equivalent, to the injector connector. Attempt to start the engine. Does the test light blink while the engine is cranking? If yes, go to next step. If no, go to «FUEL INJECTOR CIRCUIT DIAGNOSIS»(ref-153404-S42215340582003051300000) under FUEL SYSTEMS (GASOLINE) in SYSTEM & COMPONENT TESTING - 2.2L ALERO, CAVALIER, GRAND AM & SUNFIRE article.
  8. Turn ignition switch to OFF position. Connect Fuel Pressure Gauge (J 34730-1A), or equivalent, to the fuel pressure connection, located on the fuel rail. (Scheme 73) Turn ignition switch to RUN position, engine OFF. Command the fuel pump ON using a scan tool. Is the fuel pressure 50-60 psi (345-414 kPa) while the fuel pump is operating? If yes, go to next step. If no, go to «FUEL SYSTEM DIAGNOSIS (GASOLINE)»(ref-153407-S03416773192003120300000) or «FUEL SYSTEM DIAGNOSIS (CNG)»(ref-153407-S34718758222003120300000).
  9. Check for the following conditions: Collapsed air intake duct. Restricted air filter element. Check spark plugs for gas or coolant fouling. If the spark plugs are fouled, determine what caused the condition. Repair as necessary. Engine mechanical condition, worn timing chain and gears, low compression. See «MECHANICAL INSPECTION»(ref-153407-S17738930532003040400000). Restricted exhaust system. Go to «RESTRICTED EXHAUST»(ref-153405-S10795551862003051300000) under SYMPTOMS in TROUBLE SHOOTING - 2.2L ALERO, CAVALIER, GRAND AM & SUNFIRE article. The Engine Coolant Temperature (ECT) sensor is NOT close to the actual engine temperature. Go to «DTC P0117: ENGINE COOLANT TEMPERATURE SENSOR»(ref-153397-S30232025122003040400000) or «DTC P0118: ENGINE COOLANT TEMPERATURE SENSOR»(ref-153397-S02548921182003040400000) under DIAGNOSTIC TESTS in SELF-DIAGNOSTICS - 2.2L ALERO, CAVALIER, GRAND AM & SUNFIRE - GASOLINE article. Compare Manifold Absolute Pressure/Throttle Position (MAP/TP) parameters to another vehicle. The parameters should be close in value. Go to «DTC P0105: MANIFOLD ABSOLUTE PRESSURE SENSOR»(ref-153397-S36390896992003040400000) under DIAGNOSTIC TESTS in SELF-DIAGNOSTICS - 2.2L ALERO, CAVALIER, GRAND AM & SUNFIRE - GASOLINE article. Did you complete the action? If yes, go to next step.
  10. Using the scan tool, clear the DTCs. Turn ignition switch to OFF position for 30 seconds. Attempt to start the engine. Does the engine start, then continue to run? If yes, go to next step. If no, go to step 2.
  11. Allow the engine to reach operating temperature. Observe the DTC information using a scan tool. Are there any DTCs that have not been diagnosed? If yes, go to «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(ref-153397-S21975802792003040400000) under SELF-DIAGNOSTICS in SELF-DIAGNOSTICS - 2.2L ALERO, CAVALIER, GRAND AM & SUNFIRE - GASOLINE article. If no, system is okay at this time.

Scheme 73

Scheme 73
Scheme 73

System Description

The Powertrain Control Module (PCM) enables the fuel pump relay when the ignition switch is turned to RUN position. The PCM will disable the fuel pump relay within two seconds unless the PCM detects ignition reference pulses. The PCM continues to enable the fuel pump relay as long as ignition reference pulses are detected. The PCM disables the fuel pump relay within two seconds if ignition reference pulses cease to be detected and the ignition switch remains in RUN position.

The fuel tank stores the fuel supply. The electric fuel pump supplies fuel through an in-line fuel filter to the fuel injection system. The pump provides fuel at a higher rate of flow than is needed by the fuel injection system. The fuel pressure regulator maintains the correct fuel pressure to the fuel injection system. A separate pipe returns unused fuel to the fuel tank.

  1. Did you perform the Diagnostic System Check - Engine Controls. If yes, go to next step. If no, go to «DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS»(ref-153397-S21035650842003040400000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS - 2.2L ALERO, CAVALIER, GRAND AM & SUNFIRE - GASOLINE article.
  2. Turn ignition switch to RUN position, engine OFF. Command the fuel pump relay ON using a scan tool. Does the fuel pump operate? If yes, go to next step. If no, go to «FUEL PUMP ELECTRICAL CIRCUIT DIAGNOSIS»(ref-153404-S22833539312003050500000) under FUEL SYSTEMS (GASOLINE) in SYSTEM & COMPONENT TESTING - 2.2L ALERO, CAVALIER, GRAND AM & SUNFIRE article.
  3. Turn ignition switch to OFF position. Turn all accessories OFF. Connect Fuel Pressure Gauge (J 34730-1A), or equivalent, to the fuel pressure connection, located on the fuel rail. (Scheme 73) Turn ignition switch to RUN position, engine OFF. Do not start the engine. Command the fuel pump relay ON using a scan tool. The fuel pump relay may need to be commanded ON a few times to obtain the highest possible fuel pressure. Observe the fuel pressure gauge with the fuel pump commanded ON. Is the fuel pressure 50-60 psi (345-414 kPa)? If yes, go to next step. If no, go to step 10.
  4. Monitor the fuel pressure gauge for one minute. Does the fuel pressure decrease by more than 5 psi (34 kPa)? If yes, go to step 7. If no, go to next step.
  5. Relieve the fuel pressure to 10 psi (69 kPa). Monitor the fuel pressure gauge for 5 minutes. Does the fuel pressure decrease by more than 2 psi (14 kPa)? If yes, go to step 20. If no, go to next step.
  6. Operate the vehicle within the conditions to reproduce the original symptoms. Monitor the O2 and the FUEL TRIM parameters using a scan tool. Does the scan tool parameters indicate a lean condition? If yes, go to step 13. If no, go to step 8.
  7. Turn ignition switch to OFF position. Remove the hose from the fuel pressure regulator. (Scheme 74) Turn ignition switch to RUN position, engine OFF. Command the fuel pump relay ON using a scan tool. Inspect for a fuel leak from the fuel pressure regulator port. Is the fuel pressure regulator leaking fuel? If yes, go to step 19. If no, go to next step.
  8. Turn ignition switch to OFF position. Relieve the fuel pressure. See «FUEL SYSTEM PRESSURE RELEASE»(ref-153407-S10204521912003120300000). Disconnect the chassis fuel hoses from the engine compartment fuel pipes. See «FUEL LINE QUICK CONNECT FITTINGS»(ref-153402-S13027093362003040400000) in REMOVAL & INSTALLATION - CAVALIER & SUNFIRE article. Install the Fuel Line Shut-off Adapters (J 37287), or equivalent, between the chassis fuel hoses and the engine compartment fuel pipes. Open the valves on the fuel pipe shut-off adapters. Turn ignition switch to RUN position, the engine OFF. Command the fuel pump relay ON using a scan tool. Bleed the air from the fuel pressure gauge. Command the fuel pump relay ON and then OFF. Close the fuel feed pipe shut-off valve. Monitor the fuel pressure gauge for one minute. Does the fuel pressure remain constant? If yes, go to step 16. If no, go to next step.
  9. Turn ignition switch to OFF position. Open the fuel feed pipe shut-off valve. Turn ignition switch to RUN position, engine OFF. Command the fuel pump relay ON and then OFF using a scan tool. Close the fuel return pipe shut-off valve. Monitor the fuel pressure gauge for one minute. Does the fuel pressure remain constant? If yes, go to step 19. If no, go to step 17.
  10. Is the fuel pressure more than 60 psi (414 kPa)? If yes, go to next step. If no, go to step 13.
  11. Turn ignition switch to OFF position. Relieve the fuel pressure. See «FUEL SYSTEM PRESSURE RELEASE»(ref-153407-S10204521912003120300000). Disconnect the fuel return hose from the engine compartment fuel return pipe. Place the open end of the flexible fuel return hose into an approved gasoline container. Turn ignition switch to RUN position, with the engine OFF. Monitor the fuel pressure gauge while the fuel pump is operating. Is the fuel pressure 50-60 psi (345-414 kPa)? If yes, go to step 18. If no, go to next step.
  12. Inspect the fuel rail return pipe and the fuel rail outlet passage for a restriction. Did you find and correct the condition? If yes, go to step 21. If no to step 19.
  13. Turn ignition switch to OFF position. Relieve the fuel pressure. See «FUEL SYSTEM PRESSURE RELEASE»(ref-153407-S10204521912003120300000). Disconnect the fuel return hose from the engine compartment fuel return pipe. Install the Fuel Line Shut-off Adapter (J 37287), or equivalent, between the fuel return hose and the engine compartment fuel pipe. Open the valve in the fuel pipe shut-off adapter. Turn ignition switch to RUN position, engine OFF. Bleed the air from the fuel pressure gauge. Monitor the fuel pressure gauge. Do not allow the fuel pressure to exceed 75 psi (517 kPa). Excessive pressure may damage the fuel system. Command the fuel pump relay ON using a scan tool. Slowly close the valve in the fuel return pipe shut-off adapter, while the fuel pump is operating. Does the fuel pressure increase to more than 60 psi (414 kPa)? If yes, go to step 19. If no, go to next step.
  14. Check the fuel filter and fuel feed pipe for a restriction. Did you find and correct the condition? If yes, go to step 21. If no, go to next step.
  15. Check the harness connectors and the ground circuits of the fuel pump for poor connections. Did you find and correct the condition? If yes, go to step 21. If no, go to next step.
  16. Remove the fuel sender assembly. See «FUEL SENDER ASSEMBLY»(ref-153402-S21570549432003040400000) under FUEL SYSTEMS - GASOLINE in REMOVAL & INSTALLATION - CAVALIER & SUNFIRE article. Check the following items: The fuel pump flex hose for damage. The in-tank fuel pump harness connectors for poor connections. The fuel strainer for a restriction. The fuel tank for contaminants. Did you find and correct the condition? If yes, go to step 21. If no, go to step 20.
  17. Open the fuel return pipe shut-off valve. Turn ignition switch to OFF position. Raise the fuel rail, with the fuel lines connected. Turn ignition switch to RUN position, engine OFF. Command the fuel pump relay ON using a scan tool. Locate and replace the leaking fuel injector. After repair, go to step 21.
  18. Repair the restricted fuel return pipe. After repair, go to step 21.
  19. Replace the fuel pressure regulator. After repair, go to step 21.
  20. Replace the fuel sender. After repair, go to next step.
  21. Operate the system to verify the repair. Did you correct the condition? If yes, system is okay at this time. If no, go to step 3.

Scheme 74

Scheme 74
Scheme 74

The Powertrain Control Module (PCM) controls the fuel system while the vehicle is operating on CNG. The PCM receives signals from various engine sensors and determines the correct amount of fuel required by the engine. The fuel is stored in a cylindrical fuel tank. A full tank can contain fuel at 24,820 kPa (3600 psi). A High Pressure Lock-Off (HPL) solenoid in the tank and a Low Pressure Lock-Off (LPL) solenoid in the fuel line prevent fuel flow. The PCM commands ONLY the HPL open for one second at every ignition ON for a CNG prime pulse. The CNG prime pulse is performed to charge the fuel line and also allows the Fuel Tank Pressure (FTP) sensor to monitor the amount of fuel pressure in the tank. The PCM commands BOTH the HPL and the LPL open when engine RPM indicates the engine is cranking or running on CNG.

This fuel delivery system utilizes two different pressure stages to lower the fuel pressure from tank pressure down to an injector delivery pressure.

The numbers below refer to the step numbers in the diagnostic procedures.

  1. 2 - This step verifies that the HPL solenoid and the FTP sensor are functioning. A fuel tank pressure value that decreases while the engine is operating indicates the HPL is not opening or the manual tank valve is closed.
  2. 3 - This step verifies the FRP sensor is displaying the correct fuel pressure.
  3. 4 - This step tests for a leak in the fuel system between the LPL, and the fuel injectors. The fuel pressure should remain constant during the test. 5 - This step tests the HPR output pressure. If the fuel pressure is within the specified values, then the HPR, fuel lines, and filters are okay.
  4. 6 - This step tests the operation of the HPL.
  5. 8 - This step tests the HPR output pressure. If the fuel pressure is within the specified values, then the HPR, fuel lines, and filters are okay.
  6. 14 - This step verifies that a fuel filter is not the cause of the condition. If the fuel pressure is within the specified range after the fuel filter replacement, then a plugged filter was the cause of the condition.
  1. Did you perform the Diagnostic System Check - Engine Controls (Alternative Fuels). If yes, go to next step. If no, go to «DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS (ALTERNATIVE FUELS)»(ref-154639-S18635029522003051900000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS - 2.2L CAVALIER - BI-FUEL - CNG/GASOLINE article.
  2. Connect the vehicle to a CNG dispensing station and verify that the CNG fuel tank is at least 1/3 full. Fill CNG fuel tank if necessary. Observe the Fuel Tank Pressure (FTP) sensor data display using a scan tool. Attempt to start and idle the engine. Does the FTP sensor display a steady pressure at or above 1200 psi (8274 kPa)? If yes, go to next step. If no, go to step 6 .
  3. Attempt to start and idle the engine. Idle the engine until normal operating temperature is obtained. Observe and record the FRP sensor display using a scan tool. Compare the recorded scan tool display pressure values to the value range specified. Is the FRP sensor value 40-50 psi (276-345 kPa)? If yes, go to next step. If no, go to step 8 .
  4. Turn ignition switch to OFF position. Turn ignition switch to RUN position, engine OFF. Monitor the fuel rail pressure for 5 minutes. Does the fuel rail pressure drop more than 3 psi (21 kPa)? If yes, go to step 11 . If no, go to next step.
  5. Turn ignition switch to OFF position. Remove the dust cap from the LPR pressure test port. Depress the valve core stem to relieve CNG fuel pressure from the LPR. Using the components available within the CNG Electronic Pressure Gauge Kit (J 39970), or equivalent, install the transducer to the LPR test port. Connect the CNG electronic pressure gauge to the Adapter (J 39970-100), or equivalent. Connect the DMM to the CNG electronic pressure gauge. Zero the DMM using the procedure included with the CNG electronic pressure gauge. Observe the fuel pressure using the DMM while cranking the engine. Idle the engine until normal operating temperature is obtained. Rhythmic pressure fluctuation of 10-20 psi is normal. A defective HPR is not indicated unless the fluctuations become excessive. Observe and record the pressure indicated by the DMM at engine idle. Observe and record the pressure indicated by the DMM during engine load by performing the following steps: Apply the parking brake. Firmly apply and hold the brake pedal. Place the vehicle in forward gear. Observe the pressure while depressing the throttle to 75 percent or greater for a maximum of 10 seconds. Allow the engine to idle for a minimum of two minutes to cool the transmission. Compare the recorded pressure values to the value range specified. Are all of the fuel pressure values 110-210 psi (758-1448 kPa)? If yes, go to «INTERMITTENTS»(ref-154701-S16596268302003052100000) in TROUBLE SHOOTING - 2.2L CAVALIER - BI-FUEL - CNG/GASOLINE article.
  6. Turn ignition switch to RUN position, engine OFF. Command the HPL ON and OFF using a scan tool. Listen for operation of the HPL. Can operation of the HPL be heard? If yes, go to next step. If no, go to step 19 .
  7. Remove the vent boot plug. Ensure the manual tank valve is fully open by turning the screw fully counter clockwise. Did you have to open the manual tank valve? If yes, go to step 2 . If no, go to step 15 .
  8. Turn ignition switch to OFF position. Remove the dust cap from the LPR pressure test port. Depress the valve core stem to relieve CNG fuel pressure from the LPR. Using the components available within the CNG Electronic Pressure Gauge Kit (J 39970), install the transducer to the pressure test port. Connect the CNG electronic pressure gauge to the Adapter (J 39970-100), or equivalent. Connect the DMM to the CNG Electronic Pressure Gauge. Zero the DMM using the procedure included with the CNG electronic pressure gauge. Observe the fuel pressure using the DMM, while cranking the engine. Idle the engine until normal operating temperature is obtained. Rhythmic pressure fluctuation of 10-20 psi is normal. A defective HPR is not indicated unless the fluctuations become excessive. Observe and record the pressure indicated by the DMM at engine idle. Compare the recorded pressure value to the value range specified. Is the pressure value 110-210 psi (758-1448 kPa)? If yes, go to step 10 . If no, go to next step.
  9. Is the fuel pressure greater than 210 psi (1448 kPa)? If yes, go to step 17 . If no, go to step 13 .
  10. Turn ignition switch to RUN position, engine OFF. Command the LPL solenoid ON and OFF using a scan tool. Listen for operation of the LPL. Can operation of the LPL be heard? If yes, go to step 16 . If no, go to step 18 .
  11. Inspect for a fuel system leak between the LPL solenoid and the CNG fuel injectors. Replace any leaking components as necessary. Did you find and correct the condition? If yes, go to step 20 . If no, go to next step.
  12. Raise the CNG fuel rail, lines and injectors as an assembly. Command the LPL ON using a scan tool. Locate and replace the leaking CNG fuel injector. After repair, go to step 20 .
  13. Inspect the fuel line between the HPL and the HPR and the fuel line between the HPR and the LPL for kinks, bend, damage or obstruction. An obstructed fuel line may be cool or frosted near the obstruction when fuel flows through the line. Repair or replace components as necessary. Did you find and correct the condition? If yes, go to step 20 . If no, go to next step.
  14. Relieve the CNG fuel system pressure. See «FUEL SYSTEM PRESSURE RELEASE»(ref-153407-S10204521912003120300000) . Replace the CNG In-line filter. Replace the HPR filter. Observe the fuel pressure using the DMM while cranking the engine. Idle the engine until normal operating temperature is obtained. Rhythmic pressure fluctuation of 10-20 psi is normal. A defective HPR is not indicated unless the fluctuations become excessive. Observe and record the pressure indicated by the DMM at engine idle. Observe and record the pressure indicated by the DMM during engine load by performing the following steps: Apply the parking brake. Firmly depress and hold the brake pedal. Place the vehicle in forward gear. Observe the pressure while depressing the throttle to 75 percent or greater for a maximum of 10 seconds. Allow the engine to idle for a minimum of two minutes to cool the transmission. Compare the recorded pressure values to 110-210 psi (758-1448 kPa). Are all fuel pressure values 110-210 psi (758-1448 kPa)? If yes, go to step 20 . If no, go to step 17 .
  15. Replace the FTP sensor. After repair, go to step 20 .
  16. Replace the LPR. After repair, go to step 20 .
  17. Replace the HPR. After repair, go to step 20 .
  18. Replace the LPL solenoid. After repairs, go to step 20 .
  19. Replace the HPL solenoid. After repairs, go to next step.
  20. Relieve the CNG fuel system pressure. See «FUEL SYSTEM PRESSURE RELEASE»(ref-153407-S10204521912003120300000) . Turn ignition switch to OFF position. Remove all remaining test equipment. Install the IPR test port dust cap. Start and idle the engine. Inspect for CNG fuel system leaks between the fuel tank and the IPR using the Ultrasonic Leak Detector (J 41416), or equivalent. Inspect for CNG fuel system leaks at the fuel rails and injectors using Snoop® or soapy water. Repair any leaks as necessary. Clear DTC information using a scan tool. Turn ignition switch to OFF position and wait 30 seconds. Start the engine and operate the vehicle. Observe the MIL. Observe vehicle performance and driveability. Does the vehicle operate on CNG with normal driveability and no MIL illumination? If yes, system is okay at this time. If no, go to «DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS (ALTERNATIVE FUELS)»(ref-154639-S18635029522003051900000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS - 2.2L CAVALIER - BI-FUEL - CNG/GASOLINE article.

The ignition coils and Ignition Control Module (ICM) are contained within one assembly. The ignition coil/ICM assembly is mounted in the center of the engine camshaft cover, with short boots connecting the ignition coils to the spark plugs.

Each ignition coil supplies secondary voltage to a pair of spark plugs. This is called a waste spark ignition system. The Powertrain Control Module (PCM) supplies Ignition Control (IC) signals to the Ignition Control Module (ICM). The ICM fires the correct ignition coil at the correct time based on the IC signals. The ICM detects if cylinder 1 or cylinder 3 is on the compression stroke by sensing the secondary voltage and polarity of each side of the ignition coil. The ICM detects this voltage with sensing circuitry integrated into each ignition coil. The higher voltage is on the compressing cylinder. The ICM provides a synthesized cam signal to the PCM based on these inputs. This is called compression sense ignition. The PCM uses the cam signals to synchronize fuel injection.

This system consists of the following circuits

  1. Ignition 1 voltage.
  2. Ground.
  3. Camshaft Position (CMP) sensor signal.
  4. IC timing control - 2/3.
  5. IC timing control - 1/4.

The numbers below refer to the step numbers on the diagnostic procedure.

  1. 4 - This step tests for a short to voltage in the ignition circuit.
  2. 5 - This step tests for a short to voltage in the battery circuit.
  1. Did you perform the Diagnostic System Check - Engine Controls? If yes, go to next step. If no, go to «DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS»(ref-153397-S21035650842003040400000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS - 2.2L ALERO, CAVALIER, GRAND AM & SUNFIRE - GASOLINE article.
  2. Connect scan tool to Data Link Connector, located under the left side of instrument panel. Crank the engine. Observe the CKP Active Counter on the scan tool. Does the CKP Active Counter increment? If yes, go to step 6. If no, go to next step.
  3. Disconnect the CKP harness connector. Turn ignition switch to RUN position, engine OFF. Connect a DMM to the battery ground and each of the CKP sensor circuits at the CKP sensor harness connector. Does the voltage measure more than 3 volts? If yes, go to next step. If no, go to step 9.
  4. Test each CKP sensor circuit for a short to voltage. Did you find and correct the condition? If yes, go to step 25. If no, go to next step.
  5. Turn ignition switch to OFF position. Retest each CKP sensor circuit for a short to voltage. Did you find and correct the condition? If yes, go to step 25. If no, go to step 23.
  6. Turn ignition switch to OFF position. Remove the fuel pump relay, located in underhood fuse/relay block, using the Relay Puller Pliers (J 43244). Remove the ignition coil housing assembly. Not grounding the ignition coil housing, may cause erratic spark. Install a jumper wire with clips on both ends from the top of the Ignition Control Module (ICM) to ground. Install the Ignition System Diagnostic Harness (J 36012-A), or equivalent. Install Spark Tester (J 26792), or equivalent, on the No. 1 spark plug jumper wire. Ground the No. 4 (companion to No. 1) spark plug jumper wire. (Scheme 75) Crank the engine with the remaining spark plug jumper wires connected. Repeat the above steps by installing the spark tester on No. 4 and grounding No. 1. Do the same for No. 2 and No. 3 spark plug wires making sure the companion wire is grounded. Does the spark tester spark on all cylinders? If yes, go to next step. If no, go to step 11.
  7. Turn ignition switch to OFF position. Inspect for malfunctioning spark plugs. See «SPARK PLUG INSPECTION»(ref-153404-S01712188762003051400000) under IGNITION SYSTEMS in SYSTEM & COMPONENT TESTING - 2.2L ALERO, CAVALIER, GRAND AM & SUNFIRE article. Did you find and correct the condition? If yes, go to step 25. If no, go to next step.
  8. Inspect for basic engine problems. See appropriate article in ENGINES. Did you find and correct any conditions? If yes, go to step 24. If no, go to «DIAGNOSTIC AIDS»(ref-153407-S23922469112003040400000).
  9. Connect the harness connector to the CKP sensor. Disconnect the harness connector from the PCM. Measure the resistance between the CKP sensor circuits. Is the resistance 500-900 ohms? If yes, go to step 24. If no, go to next step.
  10. Test the CKP signal circuit and the low CKP reference circuit for an open, high resistance or circuits shorted together. Did you find and correct the condition? If yes, go to step 25. If no, go to next step 19.
  11. Turn ignition switch to OFF position. Remove the spark plug jumper wires. Remove the ICM from the ignition coil housing. Verify the interconnect is connected to the ICM module. Turn ignition switch to RUN position, engine OFF. Measure the voltage between the primary ignition coil voltage circuit at the ICM interconnect and a good ground. Does the voltage measure near battery voltage? If yes, go to next step. If no, go to step 13.
  12. Connect a test light between battery voltage and the control circuit for the affected ignition coil. Crank the engine. Does the test light blink? If yes, go to step 22. If no, go to step 15.
  13. Turn ignition switch to OFF position. Disconnect the ICM harness connector. Turn ignition switch to RUN position, engine OFF. Using a DMM, measure voltage at the ICM ignition 1 voltage circuit. Does the voltage measure near 12 volts? If yes, go to step 21. If no, go to next step.
  14. Check the ICM ignition 1 voltage circuit for an open or a short to ground. Did you find and correct the condition? After repair, go to step 25.
  15. Turn ignition switch to OFF position. Disconnect the ICM harness connector. Connect a DMM from the affected IC timing control circuit to ground. Set the DMM to AC voltage. Crank the engine. Does the voltage measure 0.5-2 volts? If yes, go to step 17. If no, go to next step.
  16. Test the affected IC timing control circuit for an open, a short to ground, a short to voltage or a short between the timing control circuits. Did you find and correct the condition? If yes, go to step 25. If no, go to step 23.
  17. Turn ignition switch to OFF position. Using a test light connected to positive battery voltage, probe the ICM ground circuit. Does the test light illuminate? If yes, got to step 21. If no, go to next step.
  18. Test the ICM ground circuit for an open or a short to voltage. Did you find and correct the condition? If yes, go to step 25.
  19. Inspect for poor connections at the CKP sensor. Did you find and correct the condition? If yes, go to step 25. If no, go to next step.
  20. Replace the CKP sensor. Perform the CKP variation learn procedure. See «CKP SYSTEM VARIATION LEARN PROCEDURE»(ref-153397-S15830427602003041400000) under PROGRAMMING in SELF-DIAGNOSTICS - 2.2L ALERO, CAVALIER, GRAND AM & SUNFIRE - GASOLINE article. After repair, go to step 25.
  21. Replace the ICM. After repair, go to step 25.
  22. Replace the ignition coil housing. After repair, go to step 25.
  23. Inspect for poor connections at the PCM. Did you find and correct the condition? If yes, go to step 25. If no, go to next step.
  24. Replace PCM. See appropriate REMOVAL & INSTALLATION article. Perform PCM relearn procedure. See «PROGRAMMING»(ref-153397-S04126431652003040400000) in SELF-DIAGNOSTICS - 2.2L ALERO, CAVALIER, GRAND AM & SUNFIRE article. After repair, go to next step.
  25. Attempt to start the engine. Does the engine start and continue to run? If yes, go to next step. If no, go to step 2.
  26. Turn ignition switch to OFF position for 30 seconds. Start the engine and operate the vehicle. Observe the MIL, vehicle performance, and driveability. Does the vehicle operate normally, with no MIL illumination and no stored DTCs? If yes, system is okay at this time. If no, go to «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(ref-153397-S21975802792003040400000) in SELF-DIAGNOSTICS - 2.2L ALERO, CAVALIER, GRAND AM & SUNFIRE - GASOLINE article.

Scheme 75

Scheme 75
Scheme 75

The numbers below refer to the step numbers on the diagnostic procedure.

  1. 4 - This step tests for a short to voltage in the ignition circuit.
  2. 5 - This step tests for a short to voltage in the battery circuit.
  1. Did you perform the Diagnostic System Check - Engine Controls? If yes, go to next step. If no, go to «DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS»(ref-153397-S21035650842003040400000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS - 2.2L ALERO, CAVALIER, GRAND AM & SUNFIRE - GASOLINE article.
  2. Crank the engine. Observe the CKP ACTIVE COUNTER on the scan tool. Does the CKP active counter increment? If yes, go to step 6 .
  3. Disconnect the CKP harness connector. Turn ignition switch to RUN position, engine OFF. Connect a DMM to the battery ground and each of the CKP sensor circuits at the CKP sensor harness connector. Does the voltage measure more than 3 volts? If yes, go to next step. If no, go to step 9 .
  4. Test each CKP sensor circuit for a short to voltage. Did you find and correct the condition? If yes, go to step 25 . If no, go to next step.
  5. Turn ignition switch to OFF position. Retest each CKP sensor circuit for a short to voltage. Did you find and correct the condition? If yes, go to step 25 . If no, go to step 23 .
  6. Turn ignition switch to OFF position. Remove the fuel pump relay with the Relay Puller Pliers (J 43244). Remove the ignition coil housing assembly. Install a jumper wire with clips on both ends from the top of the Ignition Control Module (ICM) to ground. Install the Ignition System Diagnostic Harness (J 36012-A), or equivalent. Install a Spark Tester (J 26792), or equivalent, on the No. 1 spark plug jumper wire. Ground the No. 4 (companion to No. 1) spark plug jumper wire. Crank the engine with the remaining spark plug jumper wires connected. Repeat the above steps by installing the spark tester on No. 4 and grounding No. 1. Do the same for No. 2 and No. 3 spark plug wires making sure the companion wire is grounded. Does the spark tester spark on all cylinders? If yes, go to next step. If no, go to step 11 .
  7. Turn ignition switch to OFF position. Inspect for malfunctioning spark plugs. Did you find and correct the condition? If yes, go to step 25 . If no, go to next step.
  8. Inspect for basic engine problems. See appropriate article in ENGINES. Did you find and correct any conditions? If yes, go to step 25 . If no, go to «DIAGNOSTIC AIDS»(ref-153407-S03950992382003082000000) .
  9. Connect the harness connector to the CKP sensor. Disconnect the harness connector from the PCM. Measure the resistance between the CKP sensor circuits. Is the resistance 500-900 ohms? If yes, go to step 24 . If no, go to next step.
  10. Test the CKP signal circuit and the low CKP reference circuit for the an open, high resistance or circuits shorted together. Did you find and correct the condition? If yes, go to step 25 . If no, go to step 19 .
  11. Turn ignition switch to OFF position. Remove the spark plug jumper wires. Remove the ICM from the ignition coil housing. Confirm that the interconnect is connected to the ICM module. Turn ignition switch to RUN position, engine OFF. Measure the voltage between the primary ignition coil voltage circuit and the ICM interconnect and a good ground. Does the voltage measure near battery voltage? If yes, go to next step. If no, go to step 13 .
  12. Remove the interconnect from the ICM. Connect a Ignition Module Tester (J 43298), or equivalent, in place of the ignition coils. Turn ignition switch to RUN position, engine OFF. Depress the test button while cranking the engine. Observe the tester. Does the appropriate 1-4 and 2-3 LEDs flash ON and OFF as the engine is cranking? If yes, go to step 22 .
  13. Turn ignition switch to OFF position. Disconnect the ICM connector. Turn ignition switch to RUN position, engine OFF. Measure the ICM ignition 1 voltage circuit with the DMM. Does the voltage measure near 12 volts? If yes, go to step 21 . If no, go to next step.
  14. Test the ICM ignition 1 voltage circuit for an open or a short to ground. After repair, go to step 25 .
  15. Turn ignition switch to OFF position. Disconnect the ICM connector. Connect a DMM from the affected IC timing control circuit to ground, set the DMM to AC voltage. Crank the engine. Does the voltage measure 0.5-2 volts? If yes, go to step 17 . If no, go to next step.
  16. Test the affected IC timing control circuit for an open, a short to ground, a short to voltage or a short between the timing control circuits. Did you find and correct the condition? If yes, go to step 25 . If no, go to step 23 .
  17. Turn ignition switch to OFF position. With a test light connected to positive battery voltage, probe the ICM ground circuit. Does the test light illuminate? If yes, go to step 21 . If no, go to next step.
  18. Test the ICM ground circuit for an open or a short to voltage. After repair, go to step 25 .
  19. Inspect for poor connections at the CKP sensor. Did you find and correct the condition? If yes, go to step 25 . If no, go to next step.
  20. Replace the CKP sensor. Perform the CKP variation learn procedure. After repair, go to step 25 .
  21. Replace the ICM. After repair, go to step 25 .
  22. Replace the ignition coil housing. After repair, go to step 25 .
  23. Inspect for poor connections at the PCM. Did you find and correct the condition? If yes, go to step 25 . If no, go to next step.
  24. Replace PCM. See appropriate REMOVAL & INSTALLATION article. Perform PCM relearn procedure. See «PROGRAMMING»(ref-153397-S04126431652003040400000) in SELF-DIAGNOSTICS - 2.2L ALERO, CAVALIER, GRAND AM & SUNFIRE - GASOLINE article. After repair, go to next step.
  25. Attempt to start the engine. Does the engine start and continue to run? If yes, go to next step. If no, go to step 2 .
  26. Turn ignition switch to OFF position for 30 seconds. Start the engine and operate the vehicle. Observe the MIL, vehicle performance, and driveability. Does the vehicle operate normally, with no MIL illumination and no stored DTCs? If yes, system is okay at this time. If no, go to «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(ref-153397-S21975802792003040400000) in SELF-DIAGNOSTICS - 2.2L ALERO, CAVALIER, GRAND AM & SUNFIRE - GASOLINE article.

More articles — Engine Controls - Basic Diagnostic Procedures - 2.2L