Engine Controls - System & Component Tests - 2.2L: Diagnosis

Test Procedure

Note. The numbers in parenthesis in the text refer to numbered components in figures.

Turn ON the Fuel Composition Tester (J 44175), or equivalent.
Verify the fuel composition tester is operational by measuring the AC frequency output using a DMM. A frequency without a fuel sample in the test cell indicates that the tester is working correctly.
Connect Fuel Pressure Gauge (J 34730-1A), or equivalent, to the fuel pressure connection, located on the fuel rail. see scheme 1
Close the bleed valve on the fuel pressure gauge.
Place the bleed hose (1) of the fuel pressure gauge into the 100 ml beaker (2). (Scheme 64)
Command the fuel pump relay ON using a scan tool.
Slowly open the bleed valve on the fuel pressure gauge, until an adequate fuel sample is obtained.
If water appears in the fuel sample, clean the fuel system and replace the fuel in the vehicle.
Pour the fuel sample from the beaker (1) into the fuel composition tester (3), until the level of the fuel is at the top of each fuel test port (2). (Scheme 65)
Observe the diagnostic LEDs on the fuel composition tester. If the Red fuel diagnostic LED is illuminated, a fuel contamination condition exists.
Measure the output frequency of the fuel composition tester.
Subtract 50 from the reading on the DMM to obtain the percentage of alcohol in the fuel sample. See examples in «FUEL COMPOSITION TEST EXAMPLES»(ref-153404-S37291004742003052300000) table.
If the fuel sample contains more than 10 percent ethanol, add gasoline to the fuel tank or replace the fuel in the vehicle.

Scheme 64

Scheme 65

Example	Frequency - Hz	Subtract 50	Ethanol Percent
A	50	50	0
B	65	50	15
C	129	50	79

FUEL COMPOSITION TEST EXAMPLES

Alcohol in Fuel Testing Procedure

The fuel sample should be drawn from the bottom of the tank so that any water present in the tank will be detected. The sample should be bright and clear. If alcohol contamination is suspected then use the following procedure to test the fuel quality.

Using a 3.38 oz. (100 ml) specified cylinder with 0.034 oz. (1 ml) graduation marks, fill the cylinder with fuel to the 3.04 oz. (90 ml) mark.
Add 0.34 oz (10 ml) of water to bring the total fluid volume to 3.38 oz. (100 ml) and install a stopper.
Shake the cylinder vigorously for 10-15 seconds.
Carefully loosen the stopper to release the pressure.
Re-install the stopper and shake the cylinder vigorously again for 10-15 seconds.
Put the cylinder on a level surface for approximately 5 minutes to allow adequate liquid separation.

If alcohol is present in the fuel, the volume of the lower layer, which would now contain both alcohol and water, will be more than 0.34 oz. (10 ml). For example, if the volume of the lower layer is increased to 0.51 oz. (15 ml), this indicates at least 5 percent alcohol in the fuel. The actual amount of alcohol may be somewhat more because this procedure does not extract all of the alcohol from the fuel.

Particulate Contaminants in Fuel Testing Procedure

The fuel sample should be drawn from the bottom of the tank so that any water present in the tank will be detected. The sample should be bright and clear. If the sample appears cloudy, or contaminated with water, as indicated by a water layer at the bottom of the sample, use the following procedure to diagnose the fuel.

Using an approved fuel container, draw approximately 0.5 liter (0.53 qt) of fuel.
Place the container on a level surface for approximately 5 minutes to allow settling of the particulate contamination. Particulate contamination will show up in various shapes and colors. Sand will typically be identified by a White or Light Brown crystals. Rubber will appear as Black and irregular particles.
Observe the fuel sample. If any physical contaminants or water are present, clean the fuel system. See «FUEL SYSTEM CLEANING»(ref-153404-S37160882142003052000000) .

Circuit 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.

Diagnostic Procedure

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.
Turn ignition switch to RUN position, engine OFF. Command the fuel pump relay ON and OFF using a scan tool. Repeat the commands as necessary. Does the fuel pump turn ON and OFF? If yes, go to «INTERMITTENTS»(ref-153405-S25155180942003040400000) in TROUBLE SHOOTING - NO CODES - 2.2L ALERO, CAVALIER, GRAND AM & SUNFIRE - GASOLINE article. If no, go to next step.
Command the fuel pump relay ON and OFF using a scan tool. Do you hear the fuel pump relay click when you command the fuel pump relay ON and OFF? If yes, go to step 9 . If no, go to next step.
Turn ignition switch to OFF position. Remove the fuel pump relay. Turn ignition switch to RUN position, engine OFF. Probe the fuel pump relay control circuit using a test light connected to a good ground. Command the fuel pump relay ON and OFF using a scan tool. Does the test light turn ON and OFF? If yes, go to next step. If no, go to step 6 .
Connect a test light between the fuel pump relay control circuit and the fuel pump relay ground circuit. Command the fuel pump relay ON and OFF using a scan tool. Does the test light turn ON and OFF? If yes, go to step 19 . If no, go to step 22 .
Does the test light remain illuminated with each command? If yes, go to next step. If no, go to step 8 .
Test the fuel pump relay control circuit for a short to voltage. Did you find and correct the condition? If yes, go to step 27 . If no, go to step 26 .
Test the fuel pump relay control circuit for a short to ground or an open. Did you find and correct the condition? If yes, go to step 27 . If no, go to step 20 .
Turn ignition switch to RUN position, engine OFF. Does the fuel pump operate continuously? If yes, go to next step. If no, go to step 11 .
Turn ignition switch to OFF position. Remove the fuel pump relay. Turn ignition switch to RUN position, engine OFF. Does the fuel pump operate continuously? If yes, go to step 21 . If no, go to step 25 .
Inspect the P/P INJR fuse (Alero and Grand Am) or F/P INJ (Cavalier and Sunfire) fuse, located in the instrument panel fuse block. Is the fuse open? If yes, go to next step. If no, go to step 14 .
Test the supply voltage circuit of the fuel pump for a short to ground between the F/P INJR or F/P INJ fuse and the fuel pump. Replace the F/P INJ fuse if necessary. Did you find and correct the condition? If yes, go to step 27 . If no, go to next step.
Connect all disconnected electrical components. Install a new F/P INJR or FP INJ fuse. Command the fuel pump relay ON using a scan tool. Inspect the F/P INJR or F/P INJ fuse. Is the F/P INJR or FP INJ fuse open? If yes, go to step 24 . If no, go to «INTERMITTENTS»(ref-153405-S25155180942003040400000) in TROUBLE SHOOTING - NO CODES - 2.2L ALERO, CAVALIER, GRAND AM & SUNFIRE - GASOLINE article.
Turn ignition switch to OFF position. Remove the fuel pump relay from the engine compartment fuse block. Turn ignition switch to RUN position, engine OFF. Probe the fuel pump relay ignition 1 voltage circuit, switch side, using a test light connected to a good ground. Does the test light illuminate? If yes, go to next step. If no, go to step 23 .
Connect a 15-amp fused jumper wire between the fuel pump relay ignition 1 voltage circuit and the fuel pump supply voltage circuit. Does the fuel pump operate? If yes, go to step 19 . If no, go to next step.
Test the fuel pump supply voltage circuit for an open or high resistance between the fuel pump relay and the fuel pump. Did you find and correct the condition? If yes, go to step 27 . If no, go to next step.
Test the ground circuit of the fuel pump for an open or high resistance. Did you find and correct the condition? If yes, go to step 27 . If no, go to next step.
Test for an intermittent and for a poor connection at the fuel sender cover. Did you find and correct the condition? If yes, go to step 27 . If no, go to step 24 .
Test for an intermittent and for a poor connection at the fuel pump relay. Did you find and correct the condition? If yes, go to step 27 . If no, go to step 25 .
Test for an intermittent and for a poor connection at the PCM. Did you find and correct the condition? If yes, go to step 27 . If no, go to step 26 .
Repair the short to voltage in the fuel pump supply voltage circuit. After repair, go to step 27 .
Repair the open or high resistance in the fuel pump relay ground circuit. After repair, go to step 27 .
Repair the open in the fuel pump relay ignition 1 voltage circuit. After repair, go to step 27 .
Replace the fuel sender. See FUEL SENDER ASSEMBLY under FUEL SYSTEMS in appropriate REMOVAL & INSTALLATION article. Replace the F/P INJR or F/P INJ fuse if necessary. After repair, go to step 27 .
Replace the fuel pump relay. After repair, go to step 27 .
Replace the PCM. See POWERTRAIN CONTROL MODULE under COMPUTERIZED ENGINE CONTROLS in 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.
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 2 .

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 (GASOLINE) article.
Did you perform the Fuel Injector Coil Test? If yes, go to next step. If no, go to «FUEL INJECTOR COIL TEST»(ref-153404-S39822063482003040400000).
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.
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. see scheme 1 Turn ignition switch to RUN position, engine OFF. Command the fuel pump ON using a scan tool. The fuel pump may need to be commanded ON a few times 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 50-60 psi (345-414 kPa)? If yes, go to next step. If no, see «FUEL SYSTEM DIAGNOSIS (GASOLINE)»(ref-153407-S03416773192003120300000) under FUEL SYSTEMS in BASIC DIAGNOSTIC PROCEDURES - 2.2L ALERO, CAVALIER, GRAND AM & SUNFIRE article.
Monitor the fuel pressure gauge for one minute. Does the fuel pressure decrease by more than 5 psi (34 kPa)? If yes, see «FUEL SYSTEM DIAGNOSIS (GASOLINE)»(ref-153407-S03416773192003120300000) under FUEL SYSTEMS in BASIC DIAGNOSTIC PROCEDURES - 2.2L ALERO, CAVALIER, GRAND AM & SUNFIRE article. If no, go to next step.
Connect the Fuel Injector Tester (J 39021), or equivalent, to a fuel injector using Injector Tester Adapter (J 39021-380), or equivalent. Set the amperage supply selector switch on the fuel injector tester to the BALANCE TEST 0.5-2.5 AMP position. Command the fuel pump relay ON and then OFF using a scan tool. Record the fuel pressure indicated by the fuel pressure gauge after the fuel pressure stabilizes. This is the first pressure reading. The fuel pressure may rise after the fuel injector stops pulsing. Record the fuel pressure value immediately after the fuel injector stops pulsing. Do not record the higher fuel pressure value. Energize the fuel injector by depressing the PUSH TO START TEST button on the fuel injector tester. Record the fuel pressure indicated by the fuel pressure gauge after the fuel injector has stopped pulsing. This is the second pressure reading. Repeat procedure for each fuel injector. Subtract the second pressure reading from the first 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. Is the difference between any individual pressure drop and the average pressure drop more than 1.5 psi (10 kPa)? If yes, go to next step. If no, see «TROUBLE SHOOTING - NO CODES - 2.2L ALERO, CAVALIER, GRAND AM & SUNFIRE - GASOLINE»(ref-153405) article.
Replace the affected fuel injectors. After repair, go to next step.
Operate the system to verify the repair. Did you correct the condition? If yes, system is okay at this time. If no, see «TROUBLE SHOOTING - NO CODES - 2.2L ALERO, CAVALIER, GRAND AM & SUNFIRE - GASOLINE»(ref-153405) article.

Scheme 66

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.
Did you perform the Fuel Injector Coil Test? If yes, go to next step. If no, go to «FUEL INJECTOR COIL TEST»(ref-153404-S39822063482003040400000).
Observe the ECT Sensor parameter using a scan tool. Is the ECT Sensor parameter less than 201°F (94°C)? If yes, go to next step.
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. see scheme 1 Turn ignition switch to RUN position, engine OFF. The fuel pump relay may need to be commanded ON a few times to obtain the highest possible fuel pressure. Do not start the engine. Command the fuel pump relay ON using the scan tool. Observe the fuel pressure gauge, with the fuel pump operating. Is the fuel pressure 50-60 psi (345-414 kPa)? If yes, go to next step. If no, go to «FUEL SYSTEM DIAGNOSIS (GASOLINE)»(ref-153407-S03416773192003120300000) under FUEL SYSTEMS in BASIC DIAGNOSTIC PROCEDURES - 2.2L ALERO, CAVALIER, GRAND AM & SUNFIRE article.
Monitor the fuel pressure gauge for one minute. Does the fuel pressure decrease by more than 5 psi (34 kPa)? If yes, go to «FUEL SYSTEM DIAGNOSIS (GASOLINE)»(ref-153407-S03416773192003120300000) under FUEL SYSTEMS in BASIC DIAGNOSTIC PROCEDURES - 2.2L ALERO, CAVALIER, GRAND AM & SUNFIRE article. If no, go to next step.
Using 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 first 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 second 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. Is the difference between any individual pressure drop and the average pressure drop more than 1.5 psi (10 kPa)? If yes, go to next step. If no, go to «SYMPTOM DIAGNOSIS»(ref-153405-S39796951442003040400000) in TROUBLE SHOOTING - NO CODES - 2.2L ALERO, CAVALIER, GRAND AM & SUNFIRE - GASOLINE article.
Replace the affected fuel injectors. After repair, go to next step.
Operate the system to verify the repair. Did you correct the condition? If yes, system is okay at this time. If no, go to «SYMPTOM DIAGNOSIS»(ref-153405-S39796951442003040400000) in TROUBLE SHOOTING - NO CODES - 2.2L ALERO, CAVALIER, GRAND AM & SUNFIRE - GASOLINE article.

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.
Observe the ECT Sensor parameter using a scan tool. Is the ECT sensor parameter 50-90°F (10-32°C)? If yes, go to next step. If no, go to step 4 .
Remove the air cleaner outlet resonator. Measure the resistance of each fuel injector using a DMM. Is the resistance 11-14 ohms for each injector? If yes, go to «FUEL INJECTOR BALANCE TEST USING SPECIAL TOOL»(ref-153404-S30411575462003040400000) or «FUEL INJECTOR BALANCE TEST USING TECH 2»(ref-153404-S27079648652003052700000) . If no, go to next step.
Measure the resistance of each fuel injector using a DMM. Record each fuel injector resistance value. Subtract the lowest resistance value from the highest resistance value. Is the difference equal to, or less than, 3 ohms? If yes, go to «FUEL INJECTOR BALANCE TEST USING SPECIAL TOOL»(ref-153404-S30411575462003040400000) or «FUEL INJECTOR BALANCE TEST USING TECH 2»(ref-153404-S27079648652003052700000) . If no, go to next step.
Add all of the fuel injector resistance values to obtain a total resistance value. Divide the total resistance value by the number of fuel injectors to obtain an average resistance value. Subtract the lowest individual fuel injector resistance value from the average resistance value. Compute the difference between the highest individual fuel injector resistance value and the average resistance value. Replace the fuel injector that displays the greatest resistance difference above or below the average. After repair, go to step 7 .
Replace the fuel injector or fuel injectors with resistance that is not within 11-14 ohms. After repair, go to next step.
Operate system to verify repair. Did you correct the condition? If yes, system is okay at this time. If no, go to step 2 .

Diagnostic Aids

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 the fuel injector coil test within the conditions of the customer's concern. A fuel injector condition may only be apparent at a certain temperature, or under certain conditions.

The Powertrain Control Module (PCM) enables the appropriate fuel injector pulse for each cylinder. Ignition voltage is supplied to the fuel injectors. The PCM controls each fuel injector by grounding the control circuit via a solid state device called a driver.

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.
Is DTC P0201, P0202, P0203, or P0204 set? If yes, go to «DTC P0201-P0204: INJECTOR CONTROL CIRCUIT»(ref-153397-S35042268732003040400000) under DIAGNOSTIC TESTS in SELF-DIAGNOSTICS - 2.2L ALERO, CAVALIER, GRAND AM & SUNFIRE - GASOLINE article. If no, go to next step.
Turn ignition switch to OFF position. Remove the air cleaner outlet resonator. Disconnect a fuel injector harness connector. Turn ignition switch to RUN position, engine OFF. Probe the fuel injector ignition 1 voltage circuit, fuse side, using a test light connected to a good ground. Does the test light illuminate? If yes, go to next step. If no, go to step 5 .
Remove the F/P-INJR (Alero and Grand Am) or F/P-INJ (Cavalier and Sunfire) fuse. Measure the resistance from the fuse to the fuel injector ignition 1 voltage circuit terminal using a DMM. Is the resistance more than 5 ohms? If yes, go to step 6 . If no, go to «DIAGNOSTIC AIDS»(ref-153404-S12485359312003051300000) .
Repair the open in the appropriate fuel injector ignition 1 voltage circuit. After repair, go to step 7 .
Repair the high resistance in the appropriate fuel injector ignition 1 voltage circuit. After repair, go to next step.
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 2 .

Performing the Fuel Injector Coil Test may help isolate an intermittent condition.
For an intermittent condition, see «INTERMITTENTS»(ref-153405-S25155180942003040400000) in TROUBLE SHOOTING - NO CODES - 2.2L ALERO, CAVALIER, GRAND AM & SUNFIRE - GASOLINE article.

WARNING

Gasoline or gasoline vapors are highly flammable. A fire could occur if an ignition source is present. Never drain or store gasoline or diesel fuel in an open container, due to the possibility of fire or explosion. Have a dry chemical (Class B) fire extinguisher nearby.

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.
Raise and support 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 6. If no, go to next step.
Turn ignition switch to RUN position, engine OFF. Using 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 7. If no, go to next step.
Install the Fuel Tank Cap (J 41415-40), or equivalent. Connect the Evaporative Emissions System Tester (EEST) (J 41413-200), or equivalent to the fuel tank cap adapter. (Scheme 67)and (Scheme 68). Using a scan tool, seal the EVAP system. Using the EEST, pressurize the fuel tank. Do not exceed 15 in. H2O. Did fuel leak from the fuel tank? If yes, go to step 6. If no, go to next step.
Using the EEST, maintain pressure in the fuel tank. The fuel tank may need to be partially lowered. Using the Ultrasonic Leak Detector (J 41416), or equivalent, test for leaks above the fuel level in the following locations. (Scheme 69) 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, hose and fuel fill cap. Did you locate a fuel leak? If yes, go to next step. If no, see «DIAGNOSTIC AIDS»(ref-153404-S33766214342003040400000).
Replace the fuel tank. After repair, go to step 8.
Replace the leaking fuel pipe. After repair, go to next step.
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 2.

Scheme 67

Scheme 68

Scheme 69

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.
Movement of the EVAP pipes or fuel pipes may help find an intermittent condition.

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.
Observe the Engine Coolant Temperature (ECT) parameter using a scan tool. Is the ECT value 50-90°F (10-32°C)? If yes, go to next step. If no, go to step 4 .
Measure the resistance of each CNG fuel injector using a DMM. Do any of the fuel injectors display a resistance outside 1-2 ohms? If yes, go to step 6 . If no, go to «DIAGNOSTIC AIDS»(ref-153404-S06783914752003052100000) .
Measure the resistance of each CNG fuel injector using a DMM. Record each fuel injector value. Subtract the lowest resistance value from the highest resistance value. Is the difference equal to, or less than, 0.5 ohm? If yes, go to «DIAGNOSTIC AIDS»(ref-153404-S06783914752003052100000) . If no, go to next step.
Add all of the CNG fuel injector resistance values, to obtain a total resistance value. Divide the total resistance value by the number of fuel injectors, to obtain an average resistance value. Subtract the lowest, and the highest, individual fuel injector resistance values from the average resistance value. Replace the CNG fuel injector that displays the greatest resistance difference, above or below the average. After repair, go to step 7 .
Replace the fuel injector or fuel injectors that are out of the specified range. After repair, go to step 7 .
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 2 .

Operating the vehicle over a wide temperature range may help isolate the fuel injector that is causing the condition.
Perform the fuel injector coil test within the conditions of the customers concern. A fuel injector condition may only be apparent at a certain temperature, or under certain conditions.
If the fuel injector coil test does not isolate the condition perform the fuel injector balance test. See «FUEL INJECTOR BALANCE TEST USING SPECIAL TOOL»(ref-153404-S27430953632003052100000) or «FUEL INJECTOR BALANCE TEST USING TECH 2»(ref-153404-S02095830022003052100000) .

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.
Did you perform the Fuel Injector Coil Test? If yes, go to next step. If no, go to «FUEL INJECTOR COIL TEST»(ref-153404-S07737270802003040400000) .
Start and idle the engine. Observe the fuel rail pressure sensor parameter using a scan tool. Is the fuel pressure 40-50 psi (276-345 kPa)? If yes, go to next step. If no, go to «FUEL SYSTEM DIAGNOSIS (CNG)»(ref-153407-S34718758222003120300000) under FUEL SYSTEMS in BASIC DIAGNOSTIC PROCEDURES - 2.2L ALERO, CAVALIER, GRAND AM & SUNFIRE article.
Turn ignition switch to OFF position. Turn ignition switch to RUN position, engine OFF. Monitor the fuel rail pressure sensor parameter using a scan tool. Does the fuel rail pressure remain constant? If yes, go to next step. If no, go to «FUEL SYSTEM DIAGNOSIS (CNG)»(ref-153407-S34718758222003120300000) under FUEL SYSTEMS in BASIC DIAGNOSTIC PROCEDURES - 2.2L ALERO, CAVALIER, GRAND AM & SUNFIRE article.
Turn ignition switch to OFF position. Connect the Fuel Injector Tester (J 39021), or equivalent, to a fuel injector. Set the amperage supply selector switch on the fuel injector tester to the BALANCE TEST 0.5-2.5 AMP position. Turn ignition switch to RUN position, engine OFF. Record the fuel pressure indicated by the fuel rail pressure sensor after the fuel pressure stabilizes. This is the first pressure reading. Record the fuel pressure value immediately after the CNG 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 CNG fuel injector by depressing the PUSH TO START TEST button on the fuel injector tester. Record the fuel pressure indicated by the fuel rail pressure sensor. This is the second fuel pressure reading. Repeat procedure for each fuel injector. Subtract the second pressure reading from the first 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 more than the average pressure drop or less than the average pressure drop by 2.0 psi (14 kPa)? If yes, go to next step. If no, go to SYMPTOMS in TROUBLE SHOOTING - NO CODES - 2.2L CAVALIER - BI-FUEL - CNG/GASOLINE article.
Replace the affected CNG fuel injector. After repair, go to next step.
Operate the vehicle to verify the repair. Does a driveability condition still exist? If yes, go to SYMPTOMS in TROUBLE SHOOTING - NO CODES - 2.2L CAVALIER - BI-FUEL - CNG/GASOLINE article. If no, system is okay at this time.

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.
Did you perform the Fuel Injector Coil Test? If yes, go to next step. If no, go to «FUEL INJECTOR COIL TEST»(ref-153404-S07737270802003040400000) .
Start and idle the engine. Observe the fuel rail pressure sensor parameter using a scan tool. Is the fuel pressure 40-50 psi (276-345 kPa)? If yes, go to next step. If no, go to «FUEL SYSTEM DIAGNOSIS (CNG)»(ref-153407-S34718758222003120300000) under FUEL SYSTEMS in BASIC DIAGNOSTIC PROCEDURES - 2.2L ALERO, CAVALIER, GRAND AM & SUNFIRE article.
Turn ignition switch to OFF position. Turn ignition switch to RUN position, engine OFF. Monitor the fuel rail pressure sensor parameter using a scan tool. Does the fuel rail pressure remain constant? If yes, go to next step. If no, go to «FUEL SYSTEM DIAGNOSIS (CNG)»(ref-153407-S34718758222003120300000) under FUEL SYSTEMS in BASIC DIAGNOSTIC PROCEDURES - 2.2L ALERO, CAVALIER, GRAND AM & SUNFIRE article.
Using 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 sensor after the fuel rail pressure stabilizes. This is the first 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 rail pressure sensor after the fuel injector has stopped pulsing. This is the second pressure reading. Press ENTER again to bring you back to the SELECT INJECTOR screen. Repeat procedure 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 2.0 psi (14 kPa)? If yes, go to next step. If no, go to «SYMPTOMS»(ref-154701-S08452033582003052100000) in TROUBLE SHOOTING - NO CODES - 2.2L CAVALIER - BI-FUEL - CNG/GASOLINE article.
Replace the affected fuel injector. After repair, go to next step.
Operate the vehicle to verify the repair. Does a driveability condition still exist? If yes, go to «SYMPTOMS»(ref-154701-S08452033582003052100000) in TROUBLE SHOOTING - NO CODES - 2.2L CAVALIER - BI-FUEL - CNG/GASOLINE article. If no, system is okay at this time.

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 or «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.
Set the parking brake and block the drive wheels. Start the engine. Turn all accessories OFF. Slowly increment the engine speed to 1700 RPM, then to 600 RPM, then to 1700 RPM using the scan tool RPM control function. Exit the RPM control function. Did the Engine Speed parameter stabilize within 100 RPM less than the commanded engine speed or within 200 RPM above the commanded RPM? If yes, see «DIAGNOSTIC AIDS»(ref-153404-S17442807832003040400000) . If no, go to next step.
Turn ignition switch to OFF position. Disconnect IAC valve harness connector. Connect IAC System Motor Analyzer (J 37027-A), or equivalent, to IAC valve. Start the engine. Using IAC system motor driver, 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.
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 .
Connect a test light between one of the IAC valve control circuits and a good ground. Start the engine. Observe the IAC Counts parameter using a scan tool. Command high RPM with the IAC Motor Driver until the IAC Counts parameter starts to increment. Command low RPM with the IAC Motor Driver until the IAC Counts parameter starts to increment. Return the engine speed to the desired idle speed parameter. Repeat procedure for the other three IAC valve control circuits. Did the test light remain ON, never flashing, while the IAC Counts were incrementing for any of the IAC valve control circuits? If yes, go to step 10 . If no, go to next step.
Did the test light 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.
Connect a test light between the IAC coil "A" low control circuit and the IAC coil "A" high control circuit. Observe the IAC Counts parameter using a scan tool and the test light. Command high RPM with the IAC Motor Driver until the IAC Counts parameter starts to increment. Command low RPM with the IAC Motor Driver until the IAC Counts parameter starts to increment. Return the Engine Speed parameter to the desired idle speed parameter. Repeat the above procedure with the test light connected between the IAC coil "B" low control circuit and the IAC coil "B" high control circuit. Did the test light stay illuminated, never flashing, while the IAC Counts were incrementing? If yes, go to next step. If no, go to step 17 .
Check for intermittent or 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 .
Turn ignition switch to OFF position. Disconnect PCM harness connectors. Using a DMM, test the circuit where the test light 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 .
Turn ignition switch to RUN position. Using a DMM, test the IAC valve control circuit where the test light 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 .
Visually and physically check 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. Check 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 .
Visually and physically inspect for the following: Throttle body damage and tampering. Throttle lever screw tampering, if equipped. Restricted air intake system. Check for a possible collapsed or clogged air intake duct, a restricted air filter element or a restriction at the throttle body intake screen, if equipped. 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 .
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.
Disconnect the PCM harness connectors. Using 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 .
Check for poor or intermittent IAC valve harness connections. Did you find and correct the condition? If yes, go to step 18 . If no, go to next step.
Replace IAC valve. After repairs, go to step 18 .
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 repairs, go to next step.
Reconnect any disconnected components. Use the scan tool to clear any DTCs. Turn ignition switch to OFF position for 30 seconds. Operate the vehicle within conditions to verify the repair. Did you correct the condition? If yes, go to next step. If no, go to step 2 .
Using 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»(ref-153397-S21975802792003040400000) in SELF-DIAGNOSTICS - 2.2L ALERO, CAVALIER, GRAND AM & SUNFIRE - GASOLINE article or «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. If no, system is okay at this time.

Check for the following conditions

High resistance in an IAC valve control circuit.
The correct Positive Crankcase Ventilation (PCV) valve, properly installed and proper operation of the PCV valve.
Proper operation and installation of all air intake components.
Proper installation and operation of the Mass Air Flow (MAF) sensor, if equipped.
A tampered with or damaged throttle stop screw.
A tampered with or damaged throttle plate, throttle shaft, throttle linkage, or cruise control linkage, if equipped.
Tampered with or damaged throttle stop screw.
Tampered with or damaged throttle plate, throttle shaft, throttle linkage, or cruise control linkage, if equipped.
A skewed high Throttle Position (TP) sensor.
Excessive deposits in throttle bore or on throttle plate.
Vacuum leaks.
A high or unstable idle condition could be caused by a non-IAC system problem that can not be overcome by the IAC valve.
High or unstable idle condition caused by a non-IAC system problem that can not be overcome by IAC valve.
If the problem is determined to be intermittent, see «INTERMITTENTS»(ref-153405-S25155180942003040400000) in TROUBLE SHOOTING - NO CODES - 2.2L ALERO, CAVALIER, GRAND AM & SUNFIRE - GASOLINE article or «INTERMITTENTS»(ref-154701-S16596268302003052100000) in TROUBLE SHOOTING - NO CODES - 2.2L CAVALIER - BI-FUEL - CNG/GASOLINE article.

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 article or «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.
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.
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 .
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.
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 .
Turn ignition switch to OFF position. Remove the fuel pump relay using the Relay Puller Pliers (J 43244), or equivalent. 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. 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 .
Turn ignition switch to OFF position. Check for malfunctioning spark plugs. Did you find and correct the condition? If yes, go to step 25 . If no, go to next step.
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-153404-S03220211302003052100000) .
Connect the harness connector to the CKP sensor. Disconnect PCM harness connectors. Measure the resistance between the CKP sensor circuits at the PCM harness connector. Is the resistance 500-900 ohms? If yes, go to step 24 . If no, go to next step.
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 step 19 .
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 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 .
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 .
Turn ignition switch to OFF position. Disconnect the ICM harness connector. Turn ignition switch to RUN position, engine OFF. Using DMM, measure the voltage ICM ignition 1 voltage circuit. Does the voltage measure near 12 volts? If yes, go to step 21 . If no, go to next step.
Check the ICM ignition 1 voltage circuit for an open or short to ground. Repair as necessary. After repair, go to step 25 .
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.
Test the affected IC timing control circuit for an open, short to ground, 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 .
Turn ignition switch to OFF position. Using a test light connected to battery positive voltage, probe the ICM ground circuit. Does the test light illuminate? If yes, go to step 21 . If no, go to next step.
Test the ICM ground circuit for an open or a short to voltage. After repair, go to step 25 .
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.
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 .
Replace the ICM. After repair, go to step 25 .
Replace the ignition coil housing. After repair, go to step 25 .
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.
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 repairs, go to next step. After repair, go to next step.
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 .
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 or «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(ref-154639-S34636817042003051900000) in SELF-DIAGNOSTICS - 2.2L CAVALIER - BI-FUEL - CNG/GASOLINE article.

A small amount of resistance in the battery positive voltage circuit to the PCM may cause a no start. Check the battery positive voltage circuit for excessive resistance or corrosion.
The PCM grounds will cause a no start only if none of them are making a good connection.
If the Crankshaft Position (CKP) sensor is loose the sensor may cause an intermittent no start by moving away from the reluctor wheel.

Did you perform the appropriate 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 article or «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.
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.
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 .
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.
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 .
Turn ignition switch to OFF position. Remove the fuel pump relay using the Relay Puller Pliers (J 43244), or equivalent. 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 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 previous 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 .
Turn ignition switch to OFF position. Check for malfunctioning spark plugs. Did you find and correct the condition? If yes, go to step 25 . If no, go to next step.
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-153404-S03220211302003052100000) .
Connect the harness connector to the CKP sensor. Disconnect PCM harness connectors. Measure the resistance between the CKP sensor circuits at the PCM harness connector. Is the resistance 500-900 ohms? If yes, go to step 24 . If no, go to next step.
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 step 19 .
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 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 .
Remove the inner-connect from the ICM. Connect 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 . If no, go to step 15 .
Turn ignition switch to OFF position. Disconnect the ICM harness connector. Turn ignition switch to RUN position, engine OFF. Using DMM, measure the voltage ICM ignition 1 voltage circuit. Does the voltage measure near 12 volts? If yes, go to step 21 . If no, go to next step.
Check the ICM ignition 1 voltage circuit for an open or short to ground. Repair as necessary. After repair, go to step 25 .
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 0.5-2.0 volts? If yes, go to step 17 . If no, go to next step.
Test the affected IC timing control circuit for an open, short to ground, 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 .
Turn ignition switch to OFF position. Using a test light connected to battery positive voltage, probe the ICM ground circuit. Does the test light illuminate? If yes, go to step 21 . If no, go to next step.
Test the ICM ground circuit for an open or a short to voltage. Repair as necessary. After repair, go to step 25 .
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.
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 .
Replace the ICM. After repair, go to step 25 .
Replace the ignition coil housing. After repair, go to step 25 .
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.
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 repairs, go to next step. After repair, go to next step.
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 .
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 or «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(ref-154639-S34636817042003051900000) in SELF-DIAGNOSTICS - 2.2L CAVALIER - BI-FUEL - CNG/GASOLINE article.

A small amount of resistance in the battery positive voltage circuit to the PCM may cause a no start. Test the battery positive voltage circuit for excessive resistance or corrosion.
The PCM grounds will cause a no start only if none of them are making a good connection.
If the Crankshaft Position (CKP) sensor is loose the sensor may cause an intermittent no start by moving away from the reluctor wheel.

Spark Plug Inspection

Note. Numbers in parenthesis correspond to numbers in referenced illustration. (Scheme 70)

Inspect the terminal post (1) for damage. Inspect for a bent or broken terminal post (1). Test for a loose terminal post (1) by twisting and pulling the post. The terminal post (1) should NOT move.
Inspect the insulator (2) for flashover or carbon tracking, soot. This is caused by the electrical charge traveling across the insulator (2) between the terminal post (1) and ground. Inspect the spark plug boot for damage. Inspect the spark plug recess area of the cylinder head for moisture, such as oil, coolant, or water. A spark plug boot that is saturated causes arcing to ground.
Inspect the insulator (2) for cracks. All or part of the electrical charge may arc through the crack instead of the electrodes (3, 4).
Inspect for evidence of improper arcing. Measure the gap between the center electrode (4) and the side electrode (3) terminals. An excessively wide electrode gap can prevent correct spark plug operation. Inspect for the correct spark plug torque. See «IGNITION SYSTEMS»(ref-151533-S14541090962002123100000) in SERVICE & SPECIFICATIONS - 2.2L ALERO, CAVALIER, GRAND AM & SUNFIRE article. Insufficient torque can prevent correct spark plug operation. An over torqued spark plug, causes the insulator (2) to crack. Inspect for signs of tracking that occurred near the insulator tip instead of the center electrode (4). Inspect for a broken or worn side electrode (3). Inspect for a broken, worn, or loose center electrode (4) by shaking the spark plug. A rattling sound indicates internal damage. A loose center electrode (4) reduces the spark intensity. Inspect for bridged electrodes (3, 4). Deposits on the electrodes (3, 4) reduce or eliminates the gap. Inspect for worn or missing platinum pads on the electrodes (3, 4) If equipped. Inspect for excessive fouling.
Inspect the spark plug recess area of the cylinder head for debris. Dirty or damaged threads can cause the spark plug not to seat correctly during installation.

Spark Plug Visual Inspection

Normal Operation - Brown to Grayish-Tan with small amounts of White powdery deposits are normal combustion by-products from fuels with additives.
Carbon Fouled - Dry, fluffy Black carbon, or soot caused by rich fuel mixtures, leaking fuel injectors, excessive fuel pressure, restricted air filter element or incorrect combustion. Reduced ignition system voltage output, weak coils worn ignition wires or incorrect spark plug gap. Excessive idling or slow speeds under light loads can keep spark plug temperatures so low that normal combustion deposits may not burn off.
Deposit Fouling - Oil, coolant, or additives that include substances such as silicone, very white coating, reduces the spark intensity. Most powdery deposits will not effect spark intensity unless they form into a glazing over the electrode.

Scheme 70

EVAP Control System Diagnosis

Manufacturer does not provide testing procedures for many individual systems and components. For EVAP Control System Diagnosis, perform related DTC testing procedure. See SELF-DIAGNOSTICS - 2.2L ALERO, CAVALIER, GRAND AM & SUNFIRE - GASOLINE article.

Inspection Procedure

CAUTION

Use the EVAP Pressure/Purge Diagnostic Station (J 41413), or equivalent, 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 ignition switch to OFF position.
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.

Inspection/Diagnosis

Disconnect the PCV hose.
Start the engine.
Check for vacuum at the hose. If there is no vacuum, check for a plugged hose or manifold port. Check for a hose that collapses when blocked (vacuum applied). Replace the plugged or the deteriorated hoses.
Allow the engine to idle at normal operating temperature.
Remove the engine oil dipstick and install a vacuum gauge on the dipstick tube.
Block off the PCV system fresh air intake passage.
Run the engine at 1500 RPM for 30 seconds, then read vacuum gauge while engine is running at 1500 RPM. If vacuum is present, this indicates that the crankcase ventilation system is functioning properly. If no vacuum is indicated, the engine may not be sealed and is drawing in outside air. Check the valve covers, the oil pan gasket or other sealing areas for leaks. See appropriate article in ENGINES. If the vacuum gauge registers a pressure, or if a vacuum gauge is pushed out of dipstick tube, check for a plugged PCV port, a plugged hose or an excessive engine blow-by.

Engine Controls - System & Component Tests - 2.2L: Diagnosis Pontiac Sunfire I