Engine Control System Testing & Engine Component Testing: Diagnosis Pontiac Bonneville X

Diagnostic Procedures

1. Perform Diagnostic System Check - Engine Controls. See DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS under SELF-DIAGNOSTIC SYSTEM in appropriate SELF-DIAGNOSTICS article. After performing Diagnostic System Check - Engine Controls, go to next step.
2. Inspect the following items and repair any condition as necessary: Vacuum lines for cracking, restrictions, and loose fit. The bypass valve actuator for sticking, binding, or damage. The bypass valve for sticking, binding, or damage. The bypass valve linkage for binding or damage. The boost control solenoid for damage. Did you find and correct the condition? If yes, go to step 16 . If no, go to next step.
3. Disconnect the boost signal hose from the bypass valve actuator. Connect a vacuum gauge to the boost signal hose. Start and idle the engine in park. Does the vacuum gauge read near 0 in. Hg? If yes, go to next step. If no, go to step 10 .
4. Connect a scan tool and command the boost control solenoid to 0 percent duty cycle. Observe the vacuum gauge. Does the vacuum gauge read more than 15 in. Hg? If yes, go to next step. If no, go to step 8 .
5. Turn OFF the ignition. Reconnect the boost signal hose to the bypass valve actuator. Disconnect the inlet vacuum signal hose from the bypass valve actuator. Connect a vacuum gauge to the inlet vacuum signal hose. Start and idle the engine in park. Does the vacuum gauge read more than 15 in. Hg? If yes, go to next step. If no, go to step 13 .
6. Turn OFF the ignition. Connect a vacuum pump to the inlet vacuum signal port on the bypass valve actuator. Slowly apply vacuum to 15 in. Hg. Does the bypass valve actuator retract? If yes, go to next step. If no, go to step 11 .
7. Reconnect the inlet vacuum signal hose to the bypass valve actuator. Disconnect the boost signal hose from the bypass valve actuator. Connect a vacuum pump to the boost signal port on the bypass valve actuator. Start and idle the engine in park. Slowly apply vacuum to 20 in. Hg. Does the bypass valve actuator extend? If yes, system is okay. If no, go to step 11 .
8. Turn OFF the ignition. Reconnect the boost signal hose to the bypass valve actuator. Disconnect the boost signal hose from the boost control solenoid. Connect a vacuum gauge to the boost signal port on the boost control solenoid. Start and idle the engine in park. Command the boost control solenoid to 0 percent duty cycle. Does the vacuum gauge read more than 15 in. Hg? If yes, go to step 15 . If no, go to next step.
9. Turn OFF the ignition. Disconnect the boost source hose from the boost control solenoid. Connect a vacuum gauge to the boost source hose. Start and idle the engine in park. Does the vacuum gauge read more than 15 in. Hg? If yes, go to next step. If no, go to step 14 .
10. Replace the boost control solenoid. After repairs, go to step 16 .
11. Inspect the bypass valve and bypass valve actuator linkage for binding, sticking or damage. Repair any condition as necessary. Did you find and correct a condition? If yes, go to step 16 . If no, go to next step.
12. Replace the bypass valve actuator. After repairs, go to step 16 .
13. Repair the inlet vacuum signal hose for a restriction or blockage. After repairs, go to step 16 .
14. Repair the boost source hose for a restriction or blockage. After repairs, go to step 16 .
15. Repair the boost signal hose for a restriction or blockage. After repairs, go to next step.
16. Reconnect any disconnected components. Use the scan tool in order to clear any DTCs that may have set. Turn OFF the ignition for 30 seconds. Operate the vehicle within conditions to verify the repair. Did you verify the repair? If yes, go to next step. If no, go to step 2 .
17. With a scan tool, observe the stored information, Capture Info. Does the scan tool display any DTCs that you have not diagnosed? If yes, see DIAGNOSTIC TROUBLE CODE DEFINITIONS in appropriate SELF-DIAGNOSTICS article. If no, system is okay.

1. Perform Diagnostic System Check - Engine Controls. See DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS under SELF-DIAGNOSTIC SYSTEM in appropriate SELF-DIAGNOSTICS article. After performing Diagnostic System Check - Engine Controls, go to next step.
2. Install a scan tool. Turn ON the ignition, with the engine OFF. With the scan tool observe the MAP sensor pressure. Compare this value to a value observed in a known-good vehicle. Is the difference between the two vehicles less than 3 kPa? If yes, go to next step. If no, go to step 7 .
3. Observe the MAP sensor pressure on the scan tool. Start the engine. Does the MAP sensor value change? If yes, go to next step. If no, go to step 7 .
4. Turn OFF the ignition. Remove the MAP sensor from the engine vacuum source. Leave the MAP sensor connected to the engine harness. Connect a Vacuum Pump (J 23738-A) to the MAP sensor. Turn ON the ignition, with the engine OFF. Observe the MAP sensor pressure as you SLOWLY apply vacuum 1 in. Hg at a time. Each one inch of vacuum should result in a 3 to 4 kPa drop in the MAP sensor pressure. Does the scan tool indicate that the MAP sensor is operating normally? If yes, go to next step. If no, go to step 15 .
5. Observe the MAP sensor pressure on the scan tool with 20 inches Hg of vacuum applied to the sensor. Is the pressure less than 34 kPa? If yes, go to next step. If no, go to step 7 .
6. Disconnect the MAP sensor from the J 23738-A. The MAP sensor pressure should return to the value observed in step 2 . Does the MAP sensor pressure return to the value observed earlier? If yes, system is okay. If no, go to step 15 .
7. Turn OFF the ignition. Disconnect the MAP sensor from the engine harness. Turn ON the ignition, with the engine OFF. Observe the MAP sensor VOLTAGE display on the scan tool. Is the voltage more than 0.1 V? If yes, go to step 11 . If no, go to next step.
8. Connect a test lamp to a good ground. Probe the 5-volt reference circuit of the MAP sensor with the test lamp. Perform a voltage drop test across the test lamp with a DMM. Does the voltage measure more than 4.4 V? If yes, go to next step. If no, go to step 12 .
9. Jumper the MAP sensor 5-volt reference circuit to the MAP sensor signal circuit using a fused jumper wire. Does the scan tool indicate that the MAP sensor voltage is near 5 V? If yes, go to next step. If no, go to step 13 .
10. Remove the jumper. Disconnect the electrical connector of the Engine Coolant Temperature (ECT) sensor. Probe the MAP sensor low reference circuit with a test lamp connected to battery positive voltage. Does the test lamp illuminate? If yes, go to step 15 . If no, go to step 14 .
11. Test the signal circuit for a short to voltage. Did you find and correct the condition? If yes, go to step 19 . If no, go to step 17 .
12. Test the 5-volt reference circuit of the MAP sensor for high resistance or an open. Did you find and correct the condition? If yes, go to step 19 . If no, go to step 17 .
13. Test the signal circuit for the following conditions: High resistance. An open. A short to ground. Did you find and correct the condition? If yes, go to step 19 . If no, go to step 17 .
14. Test the MAP sensor low reference circuit for high resistance or an open. Did you find and correct the condition? If yes, go to step 19 . If no, go to step 17 .
15. Inspect the MAP sensor connector for poor connection or terminal contact. Did you find and correct the condition? If yes, go to step 19 . If no, go to next step.
16. Replace the MAP sensor. After repairs, go to step 19 .
17. Inspect the PCM for poor connection or terminal contact. Did you find and correct the condition? If yes, go to step 19 . If no, go to next step.
18. Replace PCM. Program replacement PCM. See POWERTRAIN CONTROL MODULE under PROGRAMMING in appropriate SELF-DIAGNOSTICS article. After repairs, go to next step.
19. Use the scan tool in order to clear the DTCs that may have set. Turn OFF the ignition for 30 seconds. Start the engine. Did you correct the condition? If yes, system is okay. If no, go to step 2 .

Diagnostic Aids

Inspect for the following conditions

1. Restrictions in the MAP sensor vacuum source.
2. MAP sensor seal missing or damaged.
3. Vacuum hoses disconnected, damaged, or incorrectly routed.
4. Intake manifold vacuum leaks.
5. Vacuum leaks at the throttle body.
6. Vacuum leaks at the Exhaust Gas Recirculation (EGR) valve flange and pipes.

1. Perform Diagnostic System Check - Engine Controls. See DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS under SELF-DIAGNOSTIC SYSTEM in appropriate SELF-DIAGNOSTICS article. After performing Diagnostic System Check - Engine Controls, go to next step.
2. Install a scan tool. Turn ON the ignition, with the engine OFF. With the scan tool, observe the MAP sensor pressure. Compare this value to a value observed in a known-good vehicle. Is the difference between the vehicles less than 3 kPa? If yes, go to next step. If no, go to step 7 .
3. Observe the MAP sensor pressure on the scan tool. Start the engine. Does the MAP sensor value change? If yes, go to next step. If no, go to step 7 .
4. Turn OFF the ignition. Remove the MAP sensor from the engine vacuum source. Leave the MAP sensor connected to the engine harness. Connect a Hand Vacuum Pump (J 23738-A) to the MAP sensor port. Turn ON the ignition, with the engine OFF. Observe the MAP sensor pressure as you slowly apply vacuum 1 in. Hg at a time. Each one inch of vacuum should result in a 3 to 4 kPa drop in the MAP sensor pressure. Does the scan tool indicate that the MAP sensor is operating normally? If yes, go to next step. If no, go to step 13 .
5. Observe the MAP sensor pressure on the scan tool with 20 in. Hg of vacuum applied to the sensor. Is the MAP sensor pressure less than 34 kPa? If yes, go to next step. If no, go to step 7 .
6. Disconnect the MAP sensor from the hand held vacuum pump. Does the MAP sensor pressure return to the value observed in step 2 ? If yes, system is okay. If no, go to step 13 .
7. Turn OFF the ignition. Disconnect the MAP sensor from the engine harness. Turn ON the ignition, with the engine OFF. Observe the MAP sensor voltage display on the scan tool. Is the voltage more than 0 V? If yes, go to step 10 . If no, go to next step.
8. Jumper the MAP sensor 5-volt reference circuit to the MAP sensor signal circuit using a fused jumper wire. Observe the MAP sensor voltage display on the scan tool. Is the voltage near 5 V? If yes, go to next step. If no, go to step 11 .
9. Remove the jumper. Probe the MAP sensor low reference circuit with a test lamp connected to battery positive voltage. Does the test lamp illuminate? If yes, go to step 13 . If no, go to step 12 .
10. Test the signal circuit for a short to voltage. This short will have resistance as a complete short would have set a DTC. Did you find and correct the condition? If yes, go to step 17 . If no, go to step 15 .
11. Test the 5-volt reference and the signal circuit for high resistance or an open. Did you find and correct the condition? If yes, go to step 17 . If no, go to step 15 .
12. Test the MAP sensor low reference circuit for high resistance or an open. Did you find and correct the condition? If yes, go to step 17 . If no, go to step 15 .
13. Inspect the MAP sensor connector for poor connection or terminal contact. Did you find and correct the condition? If yes, go to step 17 . If no, go to next step.
14. Replace the MAP sensor. After repairs, go to step 17 .
15. Inspect the PCM for poor connection or terminal contact. Did you find and correct the condition? If yes, go to step 17 . If no, go to next step.
16. Replace PCM. Program replacement PCM. See POWERTRAIN CONTROL MODULE under PROGRAMMING in appropriate SELF-DIAGNOSTICS article. After repairs, go to next step.
17. Use the scan tool in order to clear the DTCs that may have set. Turn OFF the ignition for 30 seconds. Start the engine. Did you correct the condition? If yes, system is okay. If no, go to step 2 .

Inspect for the following conditions

1. Restrictions in the MAP sensor vacuum source.
2. MAP sensor seal missing or damaged.
3. Vacuum hoses disconnected, damaged, or incorrectly routed.
4. Intake manifold vacuum leaks.
5. Vacuum leaks at the throttle body.
6. Vacuum leaks at the Exhaust Gas Recirculation (EGR) valve flange and pipes.

1. Perform Diagnostic System Check - Engine Controls. See DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS under SELF-DIAGNOSTIC SYSTEM in appropriate SELF-DIAGNOSTICS article. After performing Diagnostic System Check - Engine Controls, go to next step.
2. If fuel injector coil test has been performed, go to next step. If fuel injector coil test has not been performed, perform fuel injector coil test. See «FUEL INJECTOR COIL TEST»(ref-150423-S23277073542002111200000) .
3. Observe the ECT parameter on the scan tool. Does the scan tool indicate that the ECT parameter is less than 201°F (94°C)? If yes, go to next step. If no, allow engine to cool below 201°F (94°C), then go to next step.
4. Turn OFF the ignition. Turn OFF all accessories. Install the fuel pressure gauge. Turn ON the ignition, with the engine OFF. Command the fuel pump ON with a scan tool. The fuel pump may need to be commanded ON a few times in order to obtain the highest possible fuel pressure. DO NOT start the engine. Observe the fuel pressure gauge, with the fuel pump commanded ON. Is the fuel pressure within the specified value? See «FUEL PRESSURE SPECIFICATIONS (EXCEPT SATURN)»(ref-150423-S22117630242002111200000) table or «FUEL PRESSURE SPECIFICATIONS (SATURN)»(ref-150423-S18200120992002111200000) table. If yes, go to next step. If no, see appropriate FUEL SYSTEM PRESSURE TEST article under BASIC FUEL SYSTEM CHECKS in BASIC DIAGNOSTIC PROCEDURES - CARS - EXCEPT PRIZM article.
5. Monitor the fuel pressure gauge for 1 minute. Does the fuel pressure decrease by more than 5 psi? If yes, see appropriate FUEL SYSTEM PRESSURE TEST article under BASIC FUEL SYSTEM CHECKS in BASIC DIAGNOSTIC PROCEDURES - CARS - EXCEPT PRIZM article. If no, go to next step.
6. With a scan tool, select the Fuel Injector Balance Test function, within the Special Functions menu. Select an injector to be tested. Press Enter. This will prime the fuel system. Record the fuel pressure indicated by the fuel pressure gauge after the fuel pressure stabilizes. This is the 1st pressure reading. Record the fuel pressure value immediately after the fuel injector stops pulsing. The fuel pressure may rise after the fuel injector stops pulsing. DO NOT record the higher fuel pressure value. Energize the fuel injector by depressing the Pulse Injector button on the scan tool. This will energize the injector and decrease the fuel pressure. Record the fuel pressure indicated by the fuel pressure gauge after the fuel injector has stopped pulsing. This is the 2nd pressure reading. Press Enter again to bring you back to the Select Injector screen. Repeat for each fuel injector. Subtract the 2nd pressure reading from the 1st pressure reading for one fuel injector. The result is the pressure drop value. Obtain a pressure drop value for each fuel injector. Add all of the individual pressure drop values. This is the total pressure drop. Divide the total pressure drop by the number of fuel injectors. This is the average pressure drop. Does any fuel injector have a pressure drop value that is either higher than the average pressure drop or lower than the average pressure drop by 1.5 psi? If yes, go to next step. If no, see appropriate TROUBLE SHOOTING - NO CODES article.
7. Replace the affected fuel injectors. After repairs, go to next step.
8. Operate the system in order to verify the repair. Did you correct the condition? If yes, system is okay. If no, see appropriate TROUBLE SHOOTING - NO CODES article.

FUEL PRESSURE SPECIFICATIONS (EXCEPT SATURN)

FUEL INJECTOR BALANCE TEST (SATURN)

Note. If engine is at operating temperature, allow a 10 minute cool down period.

1. On the SOHC engine, remove air intake tube.
2. Before the Fuel Injector Balance Test is started, the electrical connector should be tested using a Noid Light (J34730). Disconnect electrical connectors at fuel injectors. Connect a noid light to the female connector. Crank the engine. If the noid light does not blink, the electrical problem must be corrected before continuing.
3. Connect Gauge Bar Set (SA9127E) to fuel test port.
4. Connect the Electronic Fuel Injection Tester (SA9182E). Connect the plug to a fuel injector. Connect the red clip to the positive battery post. Connect the black clip to a clean ground. Check the power light. If it is not on, check the battery connection again.
5. Set the switch on the fuel injector tester to the 50 Pulse-10 MS setting.
6. Cycle the ignition key On/Off several times (do not start engine) and bleed off all air in the system using the pressure gauge shut-off valve.
7. Turn the ignition to the Off position for ten seconds. After ten seconds, turn ignition key to the On position (do not start engine) and record gauge pressure (1st reading).
8. Using the injector tester, pulse injector No. 1.
9. Record pressure at the instant the gauge needle stops moving (2nd reading).
10. Repeat steps 6 through 9 for the remaining injectors.
11. Add all the 2nd Readings together and divide by 4 (this is the 2nd reading Average).
12. Subtract Average of 2nd Readings from each 2nd Reading to obtain the Difference.
13. An injector is faulty if the Difference is greater than plus or minus 1.5 psi.
14. Check that all fuel injector connectors are connected. Pull back to ensure a positive engagement.
15. Remove fuel gauge bar adapter from fuel pressure test port and recap it.
16. Install air intake tube.
17. Start engine and check for leaks.

FUEL PRESSURE SPECIFICATIONS (SATURN)

1. Perform Diagnostic System Check - Engine Controls. See DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS under SELF-DIAGNOSTIC SYSTEM in appropriate SELF-DIAGNOSTICS article. After performing Diagnostic System Check - Engine Controls, go to next step.
2. Using scan tool, check Engine Coolant Temperature (ECT). Is the ECT value within 50-90°F (10-32°C)? If yes, go to next step. If no, go to step 4 .
3. Disconnect fuel injector connector. Using DVOM, measure resistance of each fuel injector. Do any of the fuel injectors display a resistance outside 11-14 ohms? If yes, go to step 6 . If no, see «DIAGNOSTIC AIDS»(ref-150423-S31947001142002111200000) .
4. Disconnect fuel injector connector. Using DVOM, measure resistance of each fuel injector. Record each fuel injector value. Subtract lowest resistance value from highest resistance value. Is the difference equal to, or less than, 3 ohms? If yes, see «DIAGNOSTIC AIDS»(ref-150423-S31947001142002111200000) . If no, go to next step.
5. Add all fuel injector resistance values, to obtain total resistance value. Divide total resistance value by number of fuel injectors, to obtain average resistance value. Subtract lowest and highest individual fuel injector resistance values from average resistance value. Replace fuel injector with greatest resistance difference, above or below average. Repair as necessary. After repairs, go to step 7 .
6. If resistance of fuel injector(s) is not 11-14 ohms, replace fuel injector(s). After repairs, go to next step.
7. Operate system in order to verify repair. Did you correct the condition? If yes, system is okay. If no, go to step 2 .

Monitoring misfire current counters, or misfire graph, may help isolate fuel injector causing condition.

Operating vehicle over a wide temperature range may help isolate fuel injector causing condition.

Perform fuel injector coil test within conditions of customers concern. A fuel injector condition may only be apparent at a certain temperature, or under certain conditions. If fuel injector coil test does not isolate condition perform fuel injector balance test. See FUEL INJECTOR BALANCE TEST .

INJECTOR LEAK TEST (1.9L)

1. Remove air induction tube and resonator.
2. Relieve fuel system pressure. See «FUEL SYSTEM PRESSURE RELIEF (SATURN)»(ref-149931-S31987161702002110100000) under BASIC FUEL SYSTEM CHECKS in BASIC DIAGNOSTIC PROCEDURES - CARS - EXCEPT PRIZM.
3. Remove throttle cable from throttle cable support bracket.
4. Remove upper power steering support brace.
5. Connect Gauge Bar Set (SA9127E) to fuel pressure port.
6. Remove fuel feed line clip attachment nut.
7. Remove fuel rail assembly attachment bolts and pull fuel rail back far enough so that the nozzles of the fuel injectors are visible but still in ports. Attach the fuel rail to the intake manifold with safety wire.
8. Connect fuel pressure gauge bar to pressure adapter.
9. Wipe the tips of the fuel injectors free of any fuel or debris and place a clean White towel directly under fuel injectors. The clean White towel must lightly contact each fuel injector tip. This will serve as an indicator of leaky fuel injectors by showing spots where fuel has leaked as well as block the injector ports from any debris that might enter.
10. Connect scan tool and turn ignition On.
11. Energize fuel pump using scan tool and observe the fuel injector tips for leakage of fuel. If one or more of the White towels becomes wet with fuel after five minutes, replace the faulty fuel injector. It is very difficult to measure drops of fuel from a injector. Pressure gauge reading should be approximately 40-55 psi (276-379 kPa).
12. Test assembly a minimum of two times.
13. Install bleed hose from Pressure Test Adapter (309725) into an approved container and open valve to bleed system pressure. Once pressure is bled, remove fuel gauge adapter from the fuel pressure test port and recap it.
14. Lubricate injector "O" rings with clean engine oil and install fuel rail assembly.
15. Start engine and check for leaks.

INJECTOR LEAK TEST (2.2L SATURN)

1. Remove air cleaner inlet tube.
2. Relieve fuel system pressure. See «FUEL SYSTEM PRESSURE RELIEF (SATURN)»(ref-149931-S31987161702002110100000) under BASIC FUEL SYSTEM CHECKS in BASIC DIAGNOSTIC PROCEDURES - CARS - EXCEPT PRIZM.
3. Connect Pressure Gauge Adapter (309725) to fuel pressure test port.
4. Remove fuel line attachment screw and fuel lines from clamp.
5. Remove fuel rail assembly. Pull fuel rail back far enough so that nozzles of injectors are visible but still in ports. Attach fuel rail to intake manifold with wire.
6. Connect fuel pressure gauge bar to pressure adapter.
7. Wipe tips of fuel injectors free of any fuel or debris. Place a clean White towel directly under fuel injectors. Ensure towel lightly contacts each fuel injector tip.
8. Connect scan tool and turn ignition On. Battery must be at a minimum of 12 volts when performing any fuel system test. Charge battery before proceeding if below 12 volts.
9. Using the scan tool, energize fuel pump.
10. Observe fuel injector tips for leakage of fuel. If one or more of White towels becomes wet with fuel after five minutes, replace faulty fuel injector. Pressure gauge reading should be approximately 50-60 psi (345-414 kPa).
11. Test assembly a minimum of two times.
12. Install bleed hose from Pressure Test Adapter (309725) into an approved container.
13. Open valve to bleed system pressure.
14. Remove fuel pressure adapter from fuel pressure test port.
15. Install fuel pressure test port cap.
16. Lubricate injector "O" rings with clean engine oil and install fuel rail assembly.
17. Start engine and check for leaks.

INJECTOR LEAK TEST (3.0L)

1. Relieve fuel system pressure. See «FUEL SYSTEM PRESSURE RELIEF (SATURN)»(ref-149931-S31987161702002110100000) under BASIC FUEL SYSTEM CHECKS in BASIC DIAGNOSTIC PROCEDURES - CARS - EXCEPT PRIZM.
2. Connect Fuel Flow/Pressure Adapter (SA9127E-7) to fuel pressure test port.
3. Remove fuel rail assembly. Pull fuel rail back far enough so that nozzles of injectors are visible but still in ports. Attach fuel rail to intake manifold with wire.
4. Connect Gauge Bar Set (SA9127E) to pressure adapter.
5. Wipe tips of fuel injectors free of any fuel or debris. Place a clean White towel directly under fuel injectors. Ensure towel lightly contacts each fuel injector tip.
6. Connect scan tool and turn ignition On. Battery must be at a minimum of 12 volts when performing any fuel system test. Charge battery before proceeding if below 12 volts.
7. Using scan tool, energize fuel pump.
8. Observe fuel injector tips for leakage of fuel. If one or more of the White towels becomes wet with fuel after five minutes, replace faulty fuel injector. Pressure gauge reading should be approximately 40-50 psi (276-345 kPa).
9. Test assembly a minimum of two times.
10. Install bleed hose from fuel flow/pressure adapter into an approved container.
11. Open valve to bleed system pressure.
12. Remove fuel pressure adapter from fuel pressure test port.
13. Install fuel pressure test port cap. Replace plastic fuel line retainers whenever fuel supply lines are disconnected at fuel filter and fuel rail. Install new retainer into female portion of connection. Care must be taken to assure that locking tab is centered in window of female connection. Firmly press male and female portions together until a "click" is heard, then pull firmly back to confirm engagement.
14. Lubricate injector "O" rings with clean engine oil and install fuel rail assembly.
15. Start engine and check for leaks.

1. If powertrain diagnostic system check has been performed, go to next step. If powertrain diagnostic system check has not been performed, see «DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS»(ref-140667-S19215153262002052400000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS - 2.2L CAVALIER - CNG article. After performing powertrain diagnostic system check, go to next step.
2. Turn ignition off. Locate and disconnect Low Pressure Lock-Off (LPL) solenoid connector. (Scheme 9) Connect test light between LPL solenoid connector terminal "A" (Purple wire) and ground. Attempt to start engine. If test light illuminates while engine is cranking or running, go to next step. If test light does not illuminate while engine is cranking or running, go to step 6.
3. Turn ignition off and wait 30 seconds. Turn ignition on. Using scan tool, clear any DTCs from AF ECM. Connect test light between LPL solenoid connector terminals "A" (Purple wire) and "B" (Light Blue wire). Attempt to start engine. If test light illuminates while engine is cranking or running, go to next step. If test light does not illuminate while engine is cranking or running, go to step 10.
4. Turn ignition off. Remove CNG fuel tank cover from inside trunk. Locate and disconnect High Pressure Lock-Off (HPL) solenoid connector. (Scheme 9) Connect test light between HPL solenoid connector terminal "A" (White wire) and ground. Attempt to start engine. If test light illuminates while engine is cranking or running, go to next step. If test light does not illuminate while engine is cranking or running, go to step 11.
5. Turn ignition off and wait 30 seconds. Connect test light between HPL solenoid connector terminals "A" (White wire) and "B" (Light Green wire). Turn ignition on. If test light illuminates when ignition is turned on, go to step 20. If test light does not illuminate when ignition is turned on, go to step 10.
6. Ensure engine is idling or cranking. Using a test light connected to ground, backprobe lock-off relay connector terminal No. 87 (Purple wire). Lock-off relay is located behind left front fascia, below headlight (18). (Scheme 9) If test light illuminates while engine is running or cranking, go to step 12. If test light does not illuminate while engine is running or cranking, go to next step.
7. Disconnect lock-off relay connector. Ensure engine is idling or cranking. Connect test light between lock-off relay connector terminals No. 85 (Gray wire) and No. 86 (Black wire). If test light illuminates while engine is running or cranking, go to next step. If test light does not illuminate while engine is running or cranking, go to step 9.
8. Ensure engine is idling or cranking. Connect test light between ground and lock-off relay connector terminal No. 30 (Orange wire). If test light illuminates while engine is running or cranking, go to step 16. If test light does not illuminate while engine is running or cranking, go to step 13.
9. Turn ignition off. Connect test light between ground and lock-off relay connector terminal No. 85 (Gray wire). Observe test light. Turn ignition on. Attempt to start engine. If test light illuminates while engine is running or cranking, go to step 14. If test light does not illuminate while engine is running or cranking, go to step 15.
10. Check for open or high resistance in Gray wire between lock-off relay connector terminal No. 85 and splice S004. Check for poor connections at lock-off solenoid and AF ECM. Repair as necessary. After repairs, go to step 20. If circuit and connections are okay, go to step 19.
11. Repair open in Purple wire between splice S005 and connector C454 terminal "A". Purple wire changes to White wire at C454. S005 is located approximately 24" (60 cm) from harness pass-through located below steering column (engine side). Repair open in White wire between connector C454 terminal "A" and HPL solenoid connector terminal "A". After repairs, go to step 20.
12. Repair open in Purple wire between LPL solenoid connector terminal "A" and lock-off relay connector terminal No. 87. After repairs, go to step 20.
13. Repair open in Orange wire between lock-off relay connector terminal No. 30 and splice S001, located approximately 1.5" (3.5 cm) from 4 relay break outs, toward AF ECM connector break outs below left front headlight. After repairs, go to step 20.
14. Repair open in Black wire between lock-off relay connector terminal No. 86 and ground connection located on left side of engine/transmission. After repairs, go to step 20.
15. If test light illuminated for 2 second bulb-check when ignition was first turned on, go to next step. If test light did not illuminate for 2 second bulb-check when ignition was first turned on, go to step 17.
16. Check for open or short in Purple/White wire between Ignition Control Module (ICM) connector C2 terminal "D" and PCM connector C1 terminal No. 8. For connector terminal identification, see «CONNECTOR IDENTIFICATION»(ref-140667-S31111358522002052400000) in SELF-DIAGNOSTICS - 2.2L CAVALIER - CNG article. (Scheme 10) Check for poor connections at PCM and ICM connectors. Repair as necessary. After repairs, go to step 20. If circuit and connections are okay, see «DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS»(ref-140667-S19215153262002052400000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS - 2.2L CAVALIER - CNG article.
17. Repair open in Gray wire between lock-off relay connector terminal No. 85 and splice S004. After repairs, go to step 20.
18. Replace lock-off relay. After repairs, go to step 20.
19. Replace AF ECM. See «ALTERNATE FUEL ENGINE CONTROL MODULE»(ref-150258-S32258339112002110700000) under COMPUTERIZED ENGINE CONTROLS in REMOVAL, OVERHAUL & INSTALLATION - CAVALIER & SUNFIRE article. Program (flash) AF ECM with correct vehicle software and calibration. See «ALTERNATE FUEL ENGINE CONTROL MODULE»(ref-140667-S13949165432002052400000) under PROGRAMMING in SELF-DIAGNOSTICS - 2.2L CAVALIER - CNG article. After performing repairs and procedures, go to next step.
20. Turn ignition off. Remove all test equipment. Reconnect any disconnected components and/or connectors. Using scan tool, clear DTCs from AF ECM and PCM. Turn ignition off for 30 seconds. Start engine and allow to idle. Start engine and operate vehicle noting operation of Fuel Indicator Light (FIL) and Malfunction Indicator Light (MIL). Observe vehicle performance and driveability in gasoline and alternate fuel modes. If FIL or MIL do not illuminate and vehicle performs normally, system is okay at this time. If FIL or MIL illuminate or vehicle does not performs normally, see «DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS»(ref-140667-S19215153262002052400000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS - 2.2L CAVALIER - CNG article.

Scheme 9

Scheme 10

1. If alternative fuels engine controls diagnostic system check has been performed, go to next step. If alternative fuels engine controls diagnostic system check has not been performed, see «DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS»(ref-140667-S19215153262002052400000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS - 2.2L CAVALIER - CNG article. After performing alternative fuels engine controls diagnostic system check, go to next step.
2. Ensure both alternate fuel and gasoline fuel systems have 1/4 tank of fuel. Add fuel to ensure this criteria is reached. If CNG 20-amp fuse has been removed, replace fuse in underhood fuse block. (Scheme 11) Crank and attempt to start engine. If engine starts and runs at all, go to step 4. If engine does not start and run at all, go to next step.
3. Turn ignition off and wait 30 seconds. Disconnect Black fuel pump connector C019 located at top left of engine (26). (Scheme 9) Connect test light between ground and relay side of fuel pump connector C019 terminal "A" (Gray wire). Turn ignition on. If test light illuminates for 2 seconds and turns off, go to step 14. If test light does not illuminate for 2 seconds or does not turn off, go to step 13.
4. If vehicle operates on CNG but not gasoline, go to next step. If vehicle does not operate on CNG or gasoline, or only operates on gasoline, see «DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS»(ref-140667-S19215153262002052400000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS - 2.2L CAVALIER - CNG article.
5. Turn ignition off and wait 30 seconds. Locate AF fuel pump relay. (Scheme 9) Using a test light connected to ground, backprobe AF fuel pump relay connector terminal No. 30 (Gray wire). Turn ignition on. If test light illuminates for 2 seconds and turns off, go to next step. If test light does not illuminate for 2 seconds or does not turn off, go to step 16.
6. Start engine and allow to idle. Ensure vehicle is operating on CNG. Using a test light connected to ground, backprobe AF fuel pump relay connector terminal 87A (Gray/Black wire). If test light illuminates, go to step 8. If test light does not illuminate, go to next step.
7. Using scan tool, attempt to communicate with AF ECM. With test light still connected, command AF fuel pump relay on and off. If test light illuminates when AF fuel pump relay is commanded off, go to step 10. If test light does not illuminate when AF fuel pump relay is commanded off, go to step 17.
8. Ensure engine is idling. Using a test light connected to battery voltage, backprobe AF fuel pump relay connector terminal No. 85 (Black wire). If test light illuminates, go to next step. If test light does not illuminate, go to step 18.
9. Ensure engine is idling. Using a test light connected to ground, backprobe AF fuel pump relay connector terminal No. 86 (Brown wire). If test light illuminates, go to step 21. If test light does not illuminate, go to step 19.
10. Ensure ignition is off. Remove CNG fuse (20-amp) from underhood fuse block to force a switchover to gasoline operation. Crank engine. If engine starts and runs on gasoline, go to step 23. If engine does not start and run on gasoline, go to next step.
11. Turn ignition off and wait 30 seconds. Disconnect Black fuel pump connector C019 located at top left of engine (26). (Scheme 9) Connect jumper wire between underhood relay side of AF fuel pump connector terminals "A" (Gray wire) and "B" (Gray wire). Crank engine. If engine starts and runs on gasoline, go to step 20. If engine does not start and run on gasoline, go to next step.
12. A failure exists in gasoline fuel pump, the gasoline fuel pump circuit between gasoline fuel pump and connector C019, or poor ground connection for fuel pump. Diagnose and repair as necessary. After repairs, go to step 23.
13. A failure exists in gasoline fuel pump relay circuit. If a blown gasoline fuel pump fuse is diagnosed, check for short to ground in CNG harness. Diagnose and repair as necessary. After repairs, go to step 23.
14. Monitor test light while cranking engine. If test light illuminates while engine is cranking, go to next step. If test light does not illuminate while engine is cranking, go to «NO-START - ENGINE CRANKS OKAY (2.2L & 2.4L - ALERO, CAVALIER, GRAND AM & SUNFIRE)»(ref-149931-S19123845992002110100000) under NO-START DIAGNOSIS in BASIC DIAGNOSTIC PROCEDURES - CARS - EXCEPT PRIZM article.
15. Check for open or poor connections in Gray wire between connector C019 terminal "A" and splice S004. Repair as necessary. After repairs, go to step 23. If circuit is okay, see «DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS»(ref-140667-S19215153262002052400000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS - 2.2L CAVALIER - CNG article.
16. Repair open in Gray wire between AF fuel pump relay connector terminal No. 30 and splice S004. After repairs, go to step 23.
17. Check for poor connections at AF fuel pump relay. Check for short to voltage in Brown wire between AF fuel pump relay connector terminal No. 86 and AF ECM Blue connector C001 terminal No. 30. (Scheme 13) Repair as necessary. After repairs, go to step 23. If circuit and connections are okay, go to step 21.
18. Repair open in Black wire between AF fuel pump relay connector terminal No. 85 and splice S006 located approximately 18" (40 cm) from ground connection on left side of engine. After repairs, go to step 23.
19. Check for poor connections at AF fuel pump relay. Using DVOM, check continuity of Brown wire between AF fuel pump relay connector terminal No. 86 and AF ECM Blue connector C001 terminal No. 30. (Scheme 13) Also check for short to ground in Brown wire. Repair as necessary. After repairs, go to step 23. If circuit and connections are okay, go to step 22.
20. Repair open in Gray/Black wire between AF fuel pump relay connector terminal 87A and connector C019 terminal "B". After repairs, go to step 23.
21. Replace AF fuel pump relay. After repairs, go to step 23.
22. Replace AF ECM. See «ALTERNATE FUEL ENGINE CONTROL MODULE»(ref-150258-S32258339112002110700000) under COMPUTERIZED ENGINE CONTROLS in REMOVAL, OVERHAUL & INSTALLATION - CAVALIER & SUNFIRE article. Program (flash) AF ECM with correct vehicle software and calibration. See «ALTERNATE FUEL ENGINE CONTROL MODULE»(ref-140667-S13949165432002052400000) under PROGRAMMING in SELF-DIAGNOSTICS - 2.2L CAVALIER - CNG article. After performing repairs and procedures, go to next step.
23. Turn ignition off. Remove all test equipment. Reconnect any disconnected components and/or connectors. Using scan tool, clear DTCs from AF ECM and PCM. Turn ignition off for 30 seconds. Start engine and allow to idle. Start engine and operate vehicle noting operation of Fuel Indicator Light (FIL) and Malfunction Indicator Light (MIL). Observe vehicle performance and driveability in gasoline and alternate fuel modes. If FIL or MIL do not illuminate and vehicle performs normally, system is okay at this time. If FIL or MIL illuminate or vehicle does not performs normally, see «DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS»(ref-140667-S19215153262002052400000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS - 2.2L CAVALIER - CNG article.

Scheme 11

Diagnostic Procedure

1. Perform Diagnostic System Check - Engine Controls. See «DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS»(ref-140667-S19215153262002052400000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS - 2.2L CAVALIER - CNG article. If any DTCs other than P1202 are set, diagnose those DTCs first. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(ref-140667-S18589168882002052400000) in SELF-DIAGNOSTICS - 2.2L CAVALIER - CNG article. If no DTCs other than P1202 are set, go to next step.
2. Connect vehicle to CNG dispensing equipment and verify that CNG tank is at least 1/3 full. This would be a pressure of 1200 psi (8274 kPa). Add CNG to tank as necessary to bring to proper level. Go to next step. NOTE: During next step, rhythmic pressure fluctuations of 10-20 psi are normal. A defective HPR is not indicated unless fluctuations become excessive.
3. Turn ignition off. Remove dust cap from fuel pressure test port located on fuel line near LPR. (Scheme 12) Using parts included in CNG Electronic Pressure Gauge Set (J 39970), install Fuel Test Port Adapter (J 39970-100) onto fuel pressure test port. Connect Electronic Fuel Pressure Gauge (J 39970) to adapter. Connect DVOM to gauge. Observe pressure while cranking engine. If a DTC sets that forces a switch-over to gasoline operation (for example: DTC P1202), fuel pressure can only be monitored before DTC sets. If vehicle will not idle in CNG mode, note pressures during cranking. If possible, start engine and allow to idle until engine reaches operating temperature. Record pressure on DVOM at idle. Observe and record pressure while performing the following procedures: Apply parking brake. Press and firmly hold brake pedal. Place vehicle in Drive. Depress throttle to 80 percent (power brake) for maximum of 10 seconds. Release throttle and allow engine to idle in neutral for a minimum of 2 minutes for transmission to cool. If recorded pressure values are 115-200 psi (793-1517 kPa), go to step 5. If recorded pressure values are not 115-200 psi (793-1517 kPa), go to next step.
4. If recorded pressure was more than 220 psi (1517 kPa), go to step 14. If recorded pressure was not more than 220 psi (1517 kPa), go to step 8.
5. Turn ignition off. Remove LPR primary test port plug. (Scheme 12) Connect pressure gauge adapter to LPR primary test port. Connect 0-15 PSI Pressure Gauge (J 28552) to adapter. Observe pressure while cranking engine. If a DTC sets that forces a switch-over to gasoline operation (for example: DTC P1202), fuel pressure can only be monitored before DTC sets. If vehicle will not idle in CNG mode, note pressures during cranking and go to next step. If vehicle will start and idle, run until operating temperature is reached. Record pressure while engine is idling. Observe and record pressure while performing the following procedures: Apply parking brake. Press and firmly hold brake pedal. Place vehicle in Drive. Depress throttle to 80 percent (power brake) for maximum of 10 seconds. Release throttle and allow engine to idle in neutral for a minimum of 2 minutes for transmission to cool. If recorded pressure values are 2-64 psi, go to next step. If recorded pressure values are not 2-64 psi, go to step 13.
6. Turn ignition off. Remove LPR secondary test port plug. A small amount of oil may drain from this port. Connect pressure gauge adapter to secondary test port. Install primary test port plug using teflon sealant, NOT teflon tape. Connect Slack Tube Manometer (J 7333-6) to pressure gauge adapter. Ensure vent port of manometer is closed until engine is started. Start engine and allow to idle until normal operating temperature is reached. Open vent port on manometer. Record manometer reading at idle. Observe and record manometer reading while performing the following procedures: Apply parking brake. Press and firmly hold brake pedal. Place vehicle in Drive. Depress throttle to 80 percent (power brake) for maximum of 10 seconds. Release throttle and allow engine to idle in neutral for a minimum of 2 minutes for transmission to cool. If recorded manometer values are 2-5 in. H 2 O (5.1-12.7 cm), go to step 19. If recorded manometer values are not 2-5 in. H 2 O (5.1-12.7 cm), go to next step.
7. Check for loose clamps, cracks or deterioration of vapor hoses between LPR and GMS/MCV and between GMS/MCV and Gas Distribution Adapter (GDA). Check GDA for loose or missing components or physical damage. Check that butterfly valve inside GMS/MCV rotates freely and does not drag when rotated. Repair or replace components as necessary. After repairs, go to step 20. If components are okay, go to step 13.
8. Using scan tool, command LPL on and off. Listen and feel for LPL operation as LPL solenoid is energized and de-energized. If LPL operation is heard or felt when energized, go to next step. If LPL operation is not heard or felt when energized, go to step 15.
9. Using scan tool, command HPL on and off. Listen for HPL operation as HPL solenoid is energized and de-energized. If HPL operation is heard when energized, go to next step. If HPL operation is not heard when energized, go to step 17.
10. Turn ignition off. Remove rubber access plug located on fuel tank cover inside trunk. Verify that manual lock-down Allen screw of HPL is fully seated in a counter-clockwise direction (fully open). If manual lock-down Allen screw is not fully open, open as necessary and go to step 20. If manual lock-down Allen screw is fully open, go to next step.
11. Check fuel line between HPL, HPR and LPR for kinks, bends, damage or obstructions. An obstructed fuel line may be cool or have frost on the surface near obstruction when fuel is flowing through line. Repair or replace as necessary. After repairs, go to step 20. If fuel line is okay, go to next step. NOTE: During next step, rhythmic pressure fluctuations of 10-20 psi are normal. A defective HPR is not indicated unless fluctuations become excessive.
12. Relieve fuel pressure. See «FUEL SYSTEM PRESSURE RELEASE (CNG)»(ref-150258-S41180194732002110700000) under FUEL SYSTEMS (CNG ENGINE) in REMOVAL, OVERHAUL & INSTALLATION - CAVALIER & SUNFIRE article. Replace HPR filter. See «HIGH PRESSURE FUEL REGULATOR»(ref-150258-S33518118192002110700000) under FUEL SYSTEMS (CNG ENGINE) in REMOVAL, OVERHAUL & INSTALLATION - CAVALIER & SUNFIRE article. Observe pressure while cranking engine. If a DTC sets that forces a switch-over to gasoline operation (for example: DTC P1202), fuel pressure can only be monitored before DTC sets. If vehicle will not idle in CNG mode, note pressures during cranking. If possible, start engine and allow to idle until engine reaches operating temperature. Record pressure at idle. Observe and record pressure while performing the following procedures: Apply parking brake. Press and firmly hold brake pedal. Place vehicle in Drive. Depress throttle to 80 percent (power brake) for maximum of 10 seconds. Release throttle and allow engine to idle in neutral for a minimum of 2 minutes for transmission to cool. If recorded pressure values are 115-220 psi (793-1517 kPa), go to step 17. If recorded pressure values are not 115-220 psi (793-1517 kPa), go to step 14.
13. Replace LPR. See «LOW PRESSURE REGULATOR»(ref-150258-S28245829532002110700000) under FUEL SYSTEMS (CNG ENGINE) in REMOVAL, OVERHAUL & INSTALLATION - CAVALIER & SUNFIRE article. After repairs, go to step 20.
14. Replace HPR. See «HIGH PRESSURE FUEL REGULATOR»(ref-150258-S33518118192002110700000) under FUEL SYSTEMS (CNG ENGINE) in REMOVAL, OVERHAUL & INSTALLATION - CAVALIER & SUNFIRE article. After repairs, go to step 20.
15. Disconnect low pressure lock-off solenoid connector. Connect test light between low pressure lock-off solenoid connector terminals "A" (Purple wire) and "B" (Light Blue wire). Using scan tool, command LPL solenoid on and off. If test light turns on when commanded on, go to next step. If test light does not turn on when commanded on, go to «DTC P1215: GROUND FAULT DETECTION INDICATED»(ref-140667-S09177120322002052400000) under DIAGNOSTIC TESTS in SELF-DIAGNOSTICS - 2.2L CAVALIER - CNG article.
16. Replace low pressure lock-off solenoid. See «LOW PRESSURE LOCK-OFF SOLENOID»(ref-150258-S26568693392002110700000) under FUEL SYSTEMS (CNG ENGINE) in REMOVAL, OVERHAUL & INSTALLATION - CAVALIER & SUNFIRE article. After repairs, go to step 20.
17. Disconnect high pressure lock-off solenoid connector. Connect test light between high pressure lock-off solenoid connector terminals "A" (White wire) and "B" (Light Green wire). Using scan tool, command HPL solenoid on and off. If test light turns on when commanded on, go to next step. If test light does not turn on when commanded on, go to «DTC P1215: GROUND FAULT DETECTION INDICATED»(ref-140667-S09177120322002052400000) under DIAGNOSTIC TESTS in SELF-DIAGNOSTICS - 2.2L CAVALIER - CNG article.
18. Replace high pressure lock-off solenoid. See «HIGH PRESSURE LOCK-OFF»(ref-150258-S06620230142002111200000) under FUEL SYSTEMS (CNG ENGINE) in REMOVAL, OVERHAUL & INSTALLATION - CAVALIER & SUNFIRE article. After repairs, go to step 20.
19. Observe pressure gauge and turn engine off. If pressure drops to zero within seconds of turning engine off, go to next step. If pressure does not drop to zero within seconds of turning engine off, go to step 16.
20. Relieve fuel pressure. See «FUEL SYSTEM PRESSURE RELEASE (CNG)»(ref-150258-S41180194732002110700000) under FUEL SYSTEMS (CNG ENGINE) in REMOVAL, OVERHAUL & INSTALLATION - CAVALIER & SUNFIRE article. Turn ignition off. Remove all test equipment. Ensure dust caps and plugs are reinstalled. Use teflon sealant on plugs, NOT teflon tape. Start engine and allow to idle. Using Ultrasonic Leak Detector (J 41416), check for leaks between fuel tank and Low Pressure Regulator (LPR). Check for leaks at LPR and between LPR and Gas Distribution Ring (GDR) using SNOOP® or soapy water. Repair any leaks as necessary. Using scan tool, clear any DTCs from AF ECM and PCM. Turn ignition off and wait 30 seconds. Start engine and operate vehicle noting operation of Fuel Indicator Light (FIL) and Malfunction Indicator Light (MIL). Observe vehicle performance and driveability in gasoline and alternate fuel modes. If FIL or MIL do not illuminate and vehicle performs normally, system is okay at this time. If FIL or MIL illuminate or vehicle does not perform normally, see «DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS»(ref-140667-S19215153262002052400000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS - 2.2L CAVALIER - CNG article.

Scheme 12

1. If alternative fuels Diagnostic System Check - Engine Controls has been performed, go to next step. If alternative fuels Diagnostic System Check - Engine Controls has not been performed, see «DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS»(ref-140667-S19215153262002052400000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS - 2.2L CAVALIER - CNG article. After performing alternative fuels engine controls diagnostic system check, go to next step.
2. Using scan tool, communicate with AF ECM and observe AFO SIGNAL and AFO SIGNAL COMMAND parameters. Start engine while monitoring parameters. If both parameters indicate NATURAL GAS OPERATION is enabled, go to next step. If both parameters do not indicate NATURAL GAS OPERATION is enabled, go to step 5.
3. Monitor Fuel Indicator Light (FIL) located in fuel gauge select switch. If FIL is illuminated, go to «MIL ON STEADY»(ref-140667-S01707024172002052400000) under SYSTEM TESTS in SELF-DIAGNOSTICS - 2.2L CAVALIER - CNG article. If FIL is not illuminated, go to next step.
4. Fault is not present at this time. If any additional DTCs are set and need to be repaired, go to appropriate diagnostic procedure. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(ref-140667-S18589168882002052400000) in SELF-DIAGNOSTICS - 2.2L CAVALIER - CNG article. If no additional DTCs are set, go to «DIAGNOSTIC AIDS»(ref-150423-S16063234762002111200000).
5. Using scan tool, communicate with AF ECM and observe fuel pressure sensor parameter. If fuel pressure sensor is more than 1200 psi (8274 kPa), go to next step. If fuel pressure sensor is less than 1200 psi (8274 kPa), go to step 10.
6. Using scan tool, observe AFO SIGNAL parameter and command AFO ENABLE circuit to natural gas operation. If parameter indicates NATURAL GAS OPERATION is enabled, go to next step. If parameter does not indicate NATURAL GAS OPERATION is enabled, go to step 13.
7. Natural gas operation will be disabled if any of the following conditions occur: Fuel pressure sensor indicates fuel pressure drops to less than 0.85 volt (350 psi at 70°F or 2412 kPa at 21°C). Natural gas operation will NOT be enabled until fuel pressure sensor indicates fuel pressure is more than 1.50 volts (1000 psi at 70°F or 6890 kPa at 21°C). An AF ECM DTC is set. Not all AF ECM DTCs cause a switch-over to gasoline. A wide-open Mixture Control Valve (MCV) is detected. Check MCV control circuits for proper terminal contact and circuit continuity between MCV and GMS connectors. Engine crank time is more than 8 seconds. The following conditions cause a start-up on gasoline followed by switch-over to natural gas during a vehicle decel condition: An engine coolant temperature of less than 10°F (-12°C) is detected at start-up or every 100th engine start. Test FTP sensor, Engine Coolant Temperature (ECT) sensor and MCV for proper operation. Check FPS accuracy by connecting vehicle to a CNG filling station and verifying tank pressure. Repair as necessary. After repairs, go to step 22. If no problems are found, go to next step. NOTE: A higher secondary voltage is required for CNG. A vehicle that operates normally on gasoline does not indicate a properly operating ignition system. If vehicle starts and stalls, check for malfunctioning Crankshaft Position (CKP) sensor.
8. Check ignition system voltage using ONLY Spark Tester (J 26792). Check CKP sensor for proper parameters using scan tool. Remove spark plugs and check for fouled (wet), cracked, excessively worn, incorrectly gapped, burned electrodes or heavy deposits. Check for damaged spark plug wires. While engine is running, spray plug wires with a fine mist of water and note any crossfire or misfire. Check AF ECM and PCM grounds for proper contact. Repair as necessary. After repairs, go to step 22. If no problems are found, go to next step.
9. Perform fuel system diagnosis. See «FUEL SYSTEM DIAGNOSIS»(ref-150423-S12106623842002111200000). Repair as necessary. After repairs, go to step 22. If fuel system is okay, go to step 21.
10. Start engine and allow to idle. Using scan tool, monitor fuel pressure parameter and command HPL open. If fuel pressure increases to more than 1200 psi (8274 kPa) when HPL is commanded open, go to step 15. If fuel pressure does not increase to more than 1200 psi (8274 kPa) when HPL is commanded open, go to next step. NOTE: Before performing next step, ensure manual lock-down screw of HPL manual shut-off fitting is opened by rotating Allen screw counter-clockwise until fully seated.
11. Verify CNG fuel tank is at full pressure by connecting vehicle to a CNG filling station and filling tank to full capacity. Turn ignition on. Compare dispensing station gauge reading to FPS reading on scan tool. If FTP sensor reading is close to dispensing station gauge reading, go to next step. If FTP sensor reading is not close to dispensing station gauge reading, go to FUEL GAUGE INACCURATE/INOPERATIVE (CNG) under SYSTEM TESTS in appropriate ANALOG INSTRUMENT PANELS article.
12. While monitoring fuel pressure parameter, start engine and allow to idle. Ensure vehicle is operating on alternate fuel. Monitor fuel pressure reading for a few minutes while engine idles. Review test description. See «DESCRIPTION»(ref-150423-S28208047192002111200000). If fuel pressure parameter ever drops to less than 1200 psi (8274 kPa), go to step 19. If fuel pressure parameter does not drop to less than 1200 psi (8274 kPa), go to step 22.
13. Observe AFO SIGNAL parameter for PCM. Turn ignition off for 30 seconds. Locate AF ECM and disconnect connectors. AF ECM is located behind left front fascia, below headlight. (Scheme 9) Connect a fused jumper wire between AF ECM Blue connector C001 terminal No. 3 (Pink wire) and ground. (Scheme 13) Turn ignition on. If fused jumper blows, repair short to voltage in Pink wire. If AFO signal indicates natural gas operation is enabled, go to step 16. If AFO signal does not indicate natural gas operation is enabled, go to next step.
14. Check for open in Pink wire between AF ECM and PCM connector C1 terminal No. 71. For connector terminal identification, see «CONNECTOR IDENTIFICATION»(ref-140667-S31111358522002052400000) in SELF-DIAGNOSTICS - 2.2L CAVALIER - CNG article. Check for poor connections ate PCM. Check that PCM is calibrated with proper bi-fuel information. Repair circuit connections or program PCM as necessary. After repairs, go to step 22. If no problems are found, go to step 17.
15. Check for fuel system leak or LPL that will not hold pressure when CNG system is closed. Check HPL for proper prime pulse operation. Repair as necessary and go to step 22.
16. Check for poor connections at AF ECM. Repair as necessary. After repairs, go to step 22. If connections are okay, go to step 18.
17. Replace PCM. See «POWERTRAIN CONTROL MODULE»(ref-150258-S17158143372002110700000) under COMPUTERIZED ENGINE CONTROLS in REMOVAL, OVERHAUL & INSTALLATION - CAVALIER & SUNFIRE article. Program (flash) PCM with correct vehicle software and calibration. See «POWERTRAIN CONTROL MODULE REPROGRAMMING»(ref-140667-S34504727982002052400000) under PROGRAMMING in SELF-DIAGNOSTICS - 2.2L CAVALIER CNG article. To perform CKP variation learn procedure, a switch-over to gasoline operation is necessary. Remove CNG fuse (20-amp) located in underhood fuse block to perform switch-over. Perform CKP system variation learn procedure. See «CRANKSHAFT POSITION SENSOR SYSTEM VARIATION LEARN PROCEDURE»(ref-140667-S39992957302002052400000) under PROGRAMMING in SELF-DIAGNOSTICS - 2.2L CAVALIER - CNG article. After performing repairs and procedures, go to step 18.
18. Replace AF ECM. See «ALTERNATE FUEL ENGINE CONTROL MODULE»(ref-150258-S32258339112002110700000) under COMPUTERIZED ENGINE CONTROLS in REMOVAL, OVERHAUL & INSTALLATION - CAVALIER & SUNFIRE article. Program (flash) AF ECM with correct vehicle software and calibration. See «ALTERNATE FUEL ENGINE CONTROL MODULE»(ref-140667-S13949165432002052400000) under PROGRAMMING in SELF-DIAGNOSTICS - 2.2L CAVALIER - CNG article. After performing repairs and procedures, go to step 18.
19. Locate and disconnect High Pressure Lock-Off (HPL) solenoid connector. (Scheme 9) Connect test light between HPL solenoid connector terminals "A" (White wire) and "B" (Light Green wire). Using scan tool, command HPL solenoid on and off. If test light illuminates when commanded on, go to next step. If test light does not illuminate when commanded on, go to «DTC P1215: GROUND FAULT DETECTION INDICATED»(ref-140667-S09177120322002052400000) under DIAGNOSTIC TESTS in SELF-DIAGNOSTICS - 2.2L CAVALIER - CNG article.
20. Replace high pressure lock-off solenoid. See «HIGH PRESSURE LOCK-OFF»(ref-150258-S06620230142002111200000) under FUEL SYSTEMS (CNG ENGINE) in REMOVAL, OVERHAUL & INSTALLATION - CAVALIER & SUNFIRE article. After repairs, go to step 18.
21. Replace GMS/MCV. See «GAS MASS SENSOR/MIXTURE CONTROL VALVE»(ref-150258-S12929915382002110700000) under FUEL SYSTEMS (CNG ENGINES) in REMOVAL, OVERHAUL & INSTALLATION - CAVALIER & SUNFIRE article. After repairs, go to next step.
22. Turn ignition off. Remove all test equipment. Reconnect any disconnected components and/or connectors. Using scan tool, clear DTCs from AF ECM and PCM. Turn ignition off for 30 seconds. Start engine and allow to idle. Start engine and operate vehicle noting operation of Fuel Indicator Light (FIL) and Malfunction Indicator Light (MIL). Observe vehicle performance and driveability in gasoline and alternate fuel modes. If FIL or MIL do not illuminate and vehicle performs normally, system is okay at this time. If FIL or MIL illuminate or vehicle does not performs normally, see «DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS»(ref-140667-S19215153262002052400000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS - 2.2L CAVALIER - CNG article.

Scheme 13

Scheme 14

Diagnostic information should be utilized only if concern of vehicle operator can be duplicated. An unwanted switch may occur only during specific vehicle operation. Examples of unwanted switch are as follow

1. Vehicle has an intermittently leaking Low Pressure Lock-Off (LPL) solenoid.
2. After turning engine OFF and waiting several minutes, all CNG purges from fuel lines.
3. During next ignition ON key cycle, High Pressure Lock-Off (HPL) solenoid is opened for approximately one second. At the same moment HPL is opened, AF ECM monitors fuel pressure sensor. If LPL is still leaking, CNG pressure cannot build within the system and low fuel pressure is observed by AF ECM. Detecting low fuel pressure in the system, AF ECM performs a switch-over to gasoline.
4. Vehicle may start and run on CNG during any ignition cycle in which LPL does not leak. Customer concern would be an intermittent unwanted switch to gasoline with no DTCs stored and possibly a no-start flooded condition.

If an unwanted switch only occurs during certain driving conditions, perform fuel system diagnosis and verify that fuel pressure can be maintained during all driving conditions. See FUEL SYSTEM DIAGNOSIS .

1. Perform Diagnostic System Check - Engine Controls. See DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS under SELF-DIAGNOSTIC SYSTEM in appropriate SELF-DIAGNOSTICS article.
2. Set parking brake and block drive wheels. Install scan tool. Start engine. Turn all accessories off. Using scan tool RPM control function, slowly increment engine speed to 1700 RPM, then to 600 RPM. Then to 1700 RPM. Exit RPM control function. Did the engine speed stabilize within specifications during the above test? See «RPM VARIATION LIMITS»(ref-150423-S28990715902002111500000) table. If yes, see «DIAGNOSTIC AIDS»(ref-150423-S29103557142002111200000) . If no, go to next step.
3. Turn ignition off. Disconnect IAC valve harness connector. Connect IAC System Motor Analyzer (J 37027-A) to IAC valve. Start engine. Using IAC system motor analyzer, command IAC valve in until about 600 RPM is reached and then command IAC valve out until about 1700 RPM is reached. Return engine RPM to desired idle as indicated on scan tool data list. Did the engine speed steadily decrease to near 600 RPM and steadily increase to near 1700 RPM when the IAC valve was commanded in and out? If yes, go to step 5 . If no, go to next step.
4. Did you observe an excessively high idle condition that could not be controlled with the IAC motor driver during the last test? If yes, go to step 11 . If no, go to step 12 .
5. Using a test light connected to ground, probe one IAC valve circuit at IAC valve harness connector. See WIRING DIAGRAMS article. Start engine. Using IAC system motor analyzer, command low RPM while observing scan tool until IAC counts start to increment, then command high RPM until IAC counts start to increment. Observe test light while incrementing IAC counts. Return engine to idle as indicated on scan tool data list. Repeat procedure for other three IAC valve circuits. Did the test lamp remain ON, never flashing, while the IAC counts where incrementing at any of the IAC valve circuits during the above test? If yes, go to step 10 . If no, go to next step.
6. Did the test lamp remain OFF, never flashing, while the IAC counts where incrementing at any of the IAC valve circuits during the above test? If yes, go to step 9 . If no, go to next step.
7. Using Connector Test Adapter Kit (J 35616-A) connect a test light between IAC coil "A" low circuit and IAC coil "A" high circuit at IAC valve harness connector. Using IAC system motor driver, command low RPM while observing scan tool until IAC counts start to increment, then command high RPM until IAC counts start to increment. Observe test light while incrementing IAC counts. Return engine speed to desired idle as indicated on scan tool data list. Repeat procedure on IAC coil "B" low circuit and IAC coil "B" high circuit. Did the test lamp stay illuminated, never flashing, while the IAC counts where incrementing during the above test? If yes, go to next step. If no, go to step 17 .
8. Check for poor connection at IAC valve harness connector. Did you find and correct the condition? If yes, go to step 18 . If no, go to step 13 .
9. Turn ignition off. Disconnect PCM harness connectors. With a DMM, test the circuit where the test lamp remained off for the following: An open circuit. A short to ground. A short to another IAC valve circuit. Did you find and correct the condition? If yes, go to step 18 . If no, go to step 13 .
10. Turn ignition on. With a DMM, test the circuit where the test lamp remained illuminated for the following: A short to voltage. A short to another IAC valve circuit. Did you find and correct the condition? If yes, go to step 18 . If no, go to step 13 .
11. Visually and physically inspect for the following: Throttle body damage and tampering. Skewed TP sensor signal. Throttle lever screw tampering (if equipped). Vacuum leaks. Faulty, incorrectly installed PCV valve and hose (if equipped). Throttle shaft binding. Throttle linkage or cruise control linkage binding (if equipped). Remove IAC valve. Inspect for the following: Clogged IAC passage. Excessive deposits on throttle plate. Excessive deposits in throttle bore. Excessive deposits on IAC valve pintle. Did you find and correct the condition? If yes, go to step 18 . If no, go to step 15 .
12. Visually and physically inspect for the following: Throttle body damage and tampering. Throttle lever screw tampering (if equipped). Restricted air intake system. Excessive deposits on throttle plate. Excessive deposits in throttle bore. Remove IAC valve and inspect for excessive deposits on IAC valve pintle and in IAC valve passage. Repair as necessary. Did you find and correct the condition? If yes, go to step 18 . If no, go to step 15 .
13. Check for poor PCM harness connections. Did you find and correct the condition? If yes, go to step 18 . If no, go to next step.
14. Disconnect the PCM harness connectors. With a DMM, test all IAC valve circuits for high resistance. Did you find and correct the condition? If yes, go to step 18 . If no, go to step 17 .
15. Check for poor IAC valve harness connection. Did you find and correct the condition? If yes, go to step 18 . If no, go to next step.
16. Replace IAC valve. After repairs, go to step 18 .
17. Replace PCM. See POWERTRAIN CONTROL MODULE under COMPUTERIZED ENGINE CONTROLS in appropriate REMOVAL, OVERHAUL & INSTALLATION article. Program (flash) PCM with correct vehicle software and calibration. See POWERTRAIN CONTROL MODULE REPROGRAMMING under PROGRAMMING in appropriate SELF-DIAGNOSTICS article. After repairs, go to next step.
18. Reconnect any disconnected components. Use the scan tool to clear any DTCs that may have set. Turn OFF the ignition for 30 seconds. Operate the vehicle within conditions to verify the repair. Did you verify the repair? If yes, go to next step. If no, go to step 2 .
19. With a scan tool, observe the stored information in Capture Info. Does the scan tool display any DTCs that you have not diagnosed? If yes, see DIAGNOSTIC TROUBLE CODE DEFINITIONS in appropriate SELF-DIAGNOSTICS article. If no, system is okay.

Inspect for the following conditions

1. Skewed high TP sensor.
2. Restricted air intake system.
3. Objects blocking IAC passage or throttle bore.
4. Correct Positive Crankcase Ventilation (PCV) valve, properly installed and proper operation of PCV valve (if equipped).
5. Proper operation and installation of all air intake components.
6. Proper installation and operation of Mass Air Flow (MAF) sensor (if equipped).
7. Tampered with or damaged throttle stop screw.
8. Tampered with or damaged throttle plate, throttle shaft, throttle linkage, or cruise control linkage (if equipped).
9. Excessive deposits in IAC passage or on IAC pintle.
10. Excessive deposits in throttle bore or on throttle plate.
11. Vacuum leaks
12. Excessive engine load caused by faulty transmission, power steering, alternator, etc.
13. High or unstable idle condition caused by a non-IAC system problem that can not be overcome by IAC valve.
14. Low or unstable idle condition caused by a non-IAC system problem that can not be overcome by IAC valve.

RPM VARIATION LIMITS

1. If alternative fuels engine controls diagnostic system check has been performed, go to next step. If alternative fuels engine controls diagnostic system check has not been performed, see «DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS»(ref-140667-S19215153262002052400000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS - 2.2L CAVALIER - CNG article. After performing alternative fuels engine controls diagnostic system check, go to next step.
2. Turn ignition off. Remove and inspect CNG fuse (20-amp) located in underhood fuse block. (Scheme 11) Remove and inspect PCM fuse (10-amp) located in instrument panel fuse block. If either fuse is blown, go to step 13. If both fuses are okay, go to next step.
3. Reinstall CNG and PCM fuses. Turn ignition on. Using a test light connected to ground, probe each terminal of CNG and PCM fuse. If test light illuminates at all terminals, go to step 5. If test light does not illuminate at all terminals, go to next step.
4. Check for poor fuse contact. Check for proper voltage of supply circuit to malfunctioning fuse. See POWER DISTRIBUTION article in WIRING DIAGRAMS. Repair as necessary. After repairs, go to step 22.
5. Turn ignition off. Locate and disconnect Alternate Fuel Engine Control Module (AF ECM) connectors. AF ECM is located behind left front fascia, below headlight. Turn ignition on. Using a test light connected to ground, probe AF ECM Blue connector C001 terminals No. 13 (Pink wire), No. 15 (Pink wire) and No. 16 (Orange wire). (Scheme 13) If test light illuminates at all terminals, go to next step. If test light does not illuminate at all terminals, go to step 14.
6. Using a test light connected to battery voltage, probe Black wire at AF ECM Clear/White connector C002 terminals No. 21, 22, 23 and 24. (Scheme 14) If test light illuminates at all terminals, go to step 20. If test light does not illuminate at all terminals, go to step 14.
7. Turn ignition off and wait 30 seconds. Monitor Fuel Indicator Light (FIL) located on fuel gauge select switch to left of steering column. Turn ignition on. If FIL illuminates for 2 second bulb check, go to step 9. If FIL does not illuminate for 2 second bulb check, go to next step.
8. Ensure ignition is on. Using test light connected to ground, backprobe ignition relay terminal No. 87 (Red wire). Ignition relay is located below left front headlight. (Scheme 9) If test light illuminates, go to FUEL INDICATOR LIGHT INOPERATIVE (CNG) under SYSTEM TESTS in appropriate ANALOG INSTRUMENT PANELS article. If test light does not illuminate, go to step 10.
9. Ensure ignition is on. Using test light connected to ground, backprobe ignition relay terminal No. 87 (Red wire). Ignition relay is located below left front headlight. (Scheme 9) Observe test light. Turn ignition off. If test light is illuminated with ignition off, go to step 15. If test light is not illuminated with ignition off, see «DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS»(ref-140667-S19215153262002052400000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS - 2.2L CAVALIER - CNG article.
10. Ensure ignition is on. Using test light connected to ground, backprobe ignition relay terminal No. 30 (Orange wire). If test light illuminates, go to next step. If test light does not illuminate, go to step 16.
11. Ensure ignition is on. Using test light connected to ground, backprobe ignition relay terminal No. 85 (Pink wire). If test light illuminates, go to next step. If test light does not illuminate, go to step 17.
12. Disconnect ignition relay. Ignition relay is located below left headlight. (Scheme 9) Ensure ignition is on. Connect test light between ignition relay connector terminals No. 85 (Pink wire) and No. 86 (Black wire). If test light is illuminated, go to step 19. If test light is not illuminated, go to step 18.
13. Check for cause of blown fuse. For blown CNG fuse, check for the following conditions: Shorted GMS/MCV circuit. Shorted fuel gauge select switch circuit. Shorted lock-off solenoid or circuit. Shorted AF ECM or AF ECM battery voltage supply circuit. For blown PCM fuse, check for the following conditions: Shorted ignition relay coil or circuit. Shorted AF ECM or AF ECM ignition voltage supply circuit. Shorted base vehicle circuit. See POWER DISTRIBUTION article in WRING DIAGRAMS. Repair as necessary. After repairs, go to step 22.
14. Repair open in AF ECM circuit that did not illuminate test light. After repairs, go to step 22.
15. Replace stuck ignition relay or repair short to battery voltage in Pink wire between CLS/PCM fuse (10-amp) located in instrument panel fuse block and ignition relay connector terminal No. 85. After repairs, go to step 22.
16. Repair open in Orange wire between ignition relay connector terminal No. 30 and splice S001 located approximately 1.5" (3.5 cm) from the 4 relay break outs, towards AF ECM connector break outs. After repairs, go to step 22.
17. Repair open in Pink wire between ignition relay connector terminal No. 85 and splice S028 located approximately 6" (14 cm) from ignition relay connector. After repairs, go to step 22.
18. Repair open in Black wire between ignition relay connector terminal No. 86 and ground connection located on left side of engine/transmission. After repairs, go to step 22.
19. Replace ignition relay. After repairs, go to step 22.
20. Check for poor connections at AF ECM connectors. Repair as necessary. After repairs, go to step 22. If connections are okay, go to next step.
21. Replace AF ECM. See «ALTERNATE FUEL ENGINE CONTROL MODULE»(ref-150258-S32258339112002110700000) under COMPUTERIZED ENGINE CONTROLS in REMOVAL, OVERHAUL & INSTALLATION - CAVALIER & SUNFIRE article. Program (flash) AF ECM with correct vehicle software and calibration. See «ALTERNATE FUEL ENGINE CONTROL MODULE»(ref-140667-S13949165432002052400000) under PROGRAMMING in SELF-DIAGNOSTICS - 2.2L CAVALIER - CNG article. After performing repairs and procedures, go to next step.
22. Turn ignition off. Remove all test equipment. Reconnect any disconnected components and/or connectors. Using scan tool, clear DTCs from AF ECM and PCM. Turn ignition off for 30 seconds. Start engine and allow to idle. Start engine and operate vehicle noting operation of Fuel Indicator Light (FIL) and Malfunction Indicator Light (MIL). Observe vehicle performance and driveability in gasoline and alternate fuel modes. If FIL or MIL do not illuminate and vehicle performs normally, system is okay at this time. If FIL or MIL illuminate or vehicle does not performs normally, see DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS under SELF-DIAGNOSTIC SYSTEM in appropriate SELF-DIAGNOSTICS article.

Circuit Description

There are 2 separate ignition module assemblies, one for each bank of cylinders. Each assembly contains an ignition control (IC) module and 4 ignition coils. Each IC module consists of the following circuits

1. The ignition 1 voltage
2. A ground
3. The IC timing low reference
4. The IC control circuits for cylinders 1-8

Each ignition coil connects directly to its spark plug via a short boot. The IC control circuits transmit timing pulses from the powertrain control (PCM) module to the IC modules, which trigger the coils to fire the plugs in the correct sequence. The PCM monitors each IC control circuit for improper voltage levels.

When servicing the ignition system components, use the following recommended procedures

1. If a boot remains attached to a coil or to a spark plug, twist the boot prior to removal.
2. Inspect the boot for a missing or damaged internal spring.
3. Do not re-install any component that has visible signs of damage.
4. Install the boots onto the coils until the boots are bottomed out. Then install the assembly onto the spark plugs. If this is not possible due to space limitations, start the boots onto the spark plugs and then install the coil assembly as straight down onto the plugs as possible.
5. Ensure that the boots are installed right side up.
6. Lift the module beauty cover at the end opposite the module in order to remove.
7. Repair a torn perimeter seal with room temperature vulcanizing (RTV) sealant.
8. Adhere to the torque specifications when installing the coil cassette to the cam cover and the ignition module to the coil cassette.

A suspected ignition system misfire may actually be a condition other than the secondary ignition system. Verify proper operation of the following items

1. The fuel system Fuel Injector Balance Test with Special Tool or Fuel Injector Balance Test with Tech 2 Fuel Injector Coil Test.
2. Engine Mechanical Test for base engine conditions that could produce an engine misfire. Refer to «SYMPTOMS - ENGINE MECHANICAL»(ref-153484-S15373770172005041500000) in Engine Mechanical-4.0L.

Exhaust System Check - Road Test (Saturn)

1. Remove heated oxygen sensor. Use 0-100 psi (0-690 kPa) gauge and appropriate hoses in Service Gauge Bar Kit (SA9127E).
2. Install Exhaust Back Pressure Adapter (SA9306E) into exhaust manifold. The thread designation is M18 x 1.50.
3. Connect gauge bar set SA9127E, 0-100 psi (0-861 kPa) gauge.
4. With engine at normal operating temperature, perform a 15 MPH (24 km/h) road test. Automatic transaxles should be in "D" and manual transaxles in "3rd" gear. Maximum exhaust back pressure readings are taken during short wide open throttle accelerations.
5. The maximum exhaust back pressure during wide open throttle accelerations must be less than 7.25 psi (50 kPa). If exhaust pressure exceeds specification, inspect for a dented or collapsed exhaust pipe. It may be necessary to disconnect exhaust pipe before or behind converter and repeat step 4 . If removing muffler does not lower back pressure, disconnect three way catalytic converter from exhaust manifold pipe and repeat test.
6. Replace any part of exhaust system found to be damaged.
7. Install anti-seize on heated oxygen sensor's threads and install sensor. It may be necessary to disconnect negative battery terminal in order to clear any codes set while operating engine with heated oxygen sensor removed or disconnected.

EVAP Control System Diagnosis

Note. The following procedure does not apply to 2.2L Saturn.

For EVAP control system diagnosis, see appropriate INSPECTION/MAINTENANCE PROCEDURES in appropriate SELF-DIAGNOSTICS article.

Inspection Procedure

Note. Use the EVAP Pressure/Purge Diagnostic Station (J 41413) in order to provide a clean, dry, low pressure gas source. Do not substitute any other pressurized gas source. Damage may result to the EVAP system. Turn OFF the ignition. Remove the EVAP canister purge valve. Lightly tap the EVAP canister purge valve on a hard surface. Inspect for carbon particles exiting either of the vacuum ports. If no carbon particles were detected, but a blockage was detected during a diagnostic procedure. Install the original EVAP canister purge valve and continue with the cleaning procedure. If carbon particles are found during the inspection procedure. Replace the EVAP canister purge valve and continue with the cleaning procedure. If a diagnostic procedure directed you to replace the EVAP canister purge valve and no carbon particles were detected, replace the EVAP canister purge valve and return to diagnostic procedure.

1. Perform Diagnostic System Check - Engine Controls. See DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS under SELF-DIAGNOSTIC SYSTEM in appropriate SELF-DIAGNOSTICS article.
2. Raise the vehicle. Inspect the fuel tank and fuel pipes for damage or external leaks. Did you find fuel leaking from the fuel tank? If yes, go to step 7 . If no, go to next step.
3. Turn ON the ignition, with the engine OFF. With a scan tool, command the fuel pump ON. Inspect for fuel leaking from the fuel pipes. Did fuel leak from the fuel pipes? If yes, go to step 8 . If no, go to next step.
4. Install the Fuel Tank Cap Adapter (J 41415-40). Connect the EVAP Pressure/Purge Diagnostic Station (J 41413) to the fuel tank cap adapter. With a scan tool, seal the EVAP system. DO NOT exceed 15 in. H2O. With the EVAP pressure/purge diagnostic station, pressurize the fuel tank. Did fuel leak from the fuel tank? If yes, go to step 7 . If no, go to next step.
5. With the EVAP pressure/purge diagnostic station, maintain pressure in the fuel tank. The fuel tank may need to be partially lowered. With the Ultrasonic Leak Detector (J 41416), test for leaks above the fuel level in the following locations. The fuel tank, fill limiter vent valve, pressure relief valve and rollover valves. The fuel sender housing and fuel sender seal. The Fuel Tank Pressure (FTP) sensor seal. The EVAP vapor pipes. The fuel fill pipe and hose. Did you locate a fuel leak? If yes, go to next step. If no, see «DIAGNOSTIC AIDS»(ref-150423-S32466221282002111500000) .
6. Repair the system as necessary. After repairs, system is okay.
7. Replace the fuel tank. After repairs, system is okay.
8. Replace the leaking fuel pipe. After repairs, system is okay.

1. Operate the vehicle under the condition of the customers concern. Under high temperature conditions fuel vapors may increase to the point of EVAP canister vapor saturation. Fuel vapors would then be released into the atmosphere. Once the engine is running and EVAP purge is enabled, all fuel vapor release would be eliminated.
2. Test for fuel leaking in the fuel tank and the fuel feed and return pipes.
3. Test for fuel vapor leaks in the fuel tank, fill limiter vent valve and rollover valves, the fuel fill pipe, hose and fuel fill cap, the fuel sender housing and seal, the Fuel Tank Pressure (FTP) sensor seal and the EVAP vapor pipe.
4. Movement of the EVAP pipes or fuel pipes may help find an intermittent condition.