Engine Control System - Basic Diagnostic Procedures Buick LeSabre VIII

MODEL IDENTIFICATION

MODEL IDENTIFICATION

INTRODUCTION

Before proceeding with basic diagnostic procedures, ensure testing procedure is followed, as some systems which may result in a no-start condition may cause a Diagnostic Trouble Codes (DTC) to be stored in the Powertrain Control Module (PCM). See DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS under SELF-DIAGNOSTIC SYSTEM in appropriate SELF-DIAGNOSTICS article.

If no-start condition still exists after checking and repairing all DTCs, perform a careful and complete visual inspection. Many problems result from mechanical breakdowns, poor electrical connections or damaged/misrouted vacuum hoses. Before condemning the computerized system, perform each test listed in this article.

Note. Perform all voltage tests with a Digital Volt-Ohmmeter (DVOM) with a minimum 10-megohm input impedance, unless stated otherwise in test procedure.

VISUAL INSPECTION

Visually inspect all electrical wiring, looking for chafed, stretched, cut or pinched wiring. Ensure electrical connectors fit tightly and are not corroded. Ensure vacuum hoses are properly routed and not pinched or cut. If necessary, see appropriate VACUUM DIAGRAMS article to verify routing and connections. Inspect air induction system for possible vacuum leaks.

Compression

Check engine mechanical condition with a compression gauge, vacuum gauge, or an engine analyzer. See engine analyzer manual for specific instructions. For compression specifications, see MECHANICAL CHECKS in appropriate SERVICE & ADJUSTMENT SPECIFICATIONS article.

Exhaust System Backpressure

Before replacing any components, check exhaust system for restrictions. Use a vacuum gauge or a low-pressure (0-5 psi) gauge to check exhaust system.

If a vacuum gauge is used, connect vacuum gauge hose to intake manifold vacuum port and start engine. Observe vacuum gauge. Partially open throttle and hold steady. If vacuum gauge reading slowly drops after stabilizing, exhaust system should be checked for a restriction. If using a low pressure gauge, connect gauge in one of the following manners

1. Check At AIR Check Valve Remove AIR check valve. Install backpressure tester in place of AIR check valve.
2. Check At Oxygen Sensor Remove oxygen sensor. Install backpressure tester in place of oxygen sensor. After test is completed, coat oxygen sensor threads with anti-seize compound before installation.

Diagnosis

1. Start engine and allow it to reach normal operating temperature. Increase engine speed to 2000-2500 RPM and note gauge. If reading exceeds 1.25 psi (.09 kg/cm 2 ), exhaust system is restricted.
2. Check exhaust system for collapsed pipe, heat distress and possible internal muffler failure. If none of these conditions exist, check for restricted catalytic converter. Replace as necessary.

NO-START DIAGNOSIS

Note. For circuit identification, see WIRING DIAGRAMS article.

Note. Some vehicles are equipped with anti-theft systems (VATS or PASS-Key(R)) which will not allow vehicle to be started if improper starting procedures or improperly coded ignition keys are used. Both fuel injection and cranking systems will be disabled. Loss of fuel enable signal from anti-theft decoder module should set a diagnostic trouble code in PCM memory.

Note. For terminal and circuit identification, see WIRING DIAGRAMS article.

1. Definition No start is defined as engine cranks properly, but does not start. Engine may fire a few times.

NO START - ENGINE CRANKS OKAY (1.9L)

Note. Before performing the following tests, check battery condition, engine cranking speed and for adequate fuel in tank.

General Inspection

1. Using scan tool, attempt communication with BCM and PCM. If communication can be established, go to next step. If communication cannot be established, diagnose communication problem. See appropriate BODY CONTROL MODULES article in ACCESSORIES & EQUIPMENT.
2. If BCM or PCM Passlock(R)/security system or BCM communication DTCs (P1630, P1631, U1000, U1064, U1300 or U1301) are set, diagnose these DTCs first. See appropriate SELF-DIAGNOSTICS article or appropriate BODY CONTROL MODULES article in ACCESSORIES & EQUIPMENT. If listed DTCs are not set, go to next step.
3. Using scan tool, monitor IGNITION 1 voltage. If voltage is 2 volts or greater, go to next step. If voltage is not 2 volts or greater, check PCM ignition feed circuit or PCM ground circuits for an open or poor connection. Repair as necessary.
4. If any PCM internal fault DTCs (P0601, P0602, P0603, P0606 or P1621) are set, diagnose these DTCs first. See appropriate SELF-DIAGNOSTICS article. If listed DTCs are not set, go to next step.
5. If all 4 injector circuit low DTCs (P0261, P0264, P0267 or P0270) are set, repair ignition voltage circuits between underhood junction block and fuel injectors. Check INJ fuse (10-amp) in underhood junction block. Replace if necessary. If listed DTCs are not set, go to next step.
6. If any ignition control DTCs (P0351, P0352, P1351 or P1352) are set, diagnose these DTCs first. See appropriate SELF-DIAGNOSTICS article. If listed DTCs are not set, go to next step.
7. If DTC P1635 is set, diagnose DTCs first. See appropriate SELF-DIAGNOSTICS article. If listed DTC is not set, go to next step.
8. If DTCs P0231 or P0232 are set, diagnose these DTCs first. See appropriate SELF-DIAGNOSTICS article. If listed DTCs are not set, go to next step.
9. Using scan tool, monitor EGR sensor. If voltage is less than one volt, go to next step. If voltage is not less than one volt, perform diagnostic procedure for DTC P1404. See appropriate SELF-DIAGNOSTICS article.
10. Using scan tool, monitor CMP resync counter while cranking engine. If counter increments, go to next step. If counter does not increment, go to «NO RPM DETECTED DIAGNOSIS»(/buick/lesabre/viii-2000-2005/remont/testing-diagnostics/#engine-control-system-basic-diagnostic-procedures__no-rpm-detected-diagnosis) .
11. Check for spark at plug wires No. 2 and 4. If spark is present at both plug wires, go to next step. If spark is not present at both plug wires, go to «IGNITION DIAGNOSIS»(/buick/lesabre/viii-2000-2005/remont/testing-diagnostics/#engine-control-system-basic-diagnostic-procedures__ignition-system-diagnosis) .
12. Check for fouled spark plugs. Repair as necessary. If spark plugs are okay, go to «FUEL DELIVERY DIAGNOSIS»(/buick/lesabre/viii-2000-2005/remont/testing-diagnostics/#engine-control-system-basic-diagnostic-procedures__fuel-delivery-diagnosis) .

No RPM Detected Diagnosis

1. Turn ignition off. Disconnect 80-pin PCM harness connector. Measure resistance between 7X signal high circuit and 7X signal low circuit at PCM harness connector. If resistance is 800-1600 ohms, go to next step. If resistance is less than 800 ohms, go to step 3 . If resistance is greater than 1600 ohms, go to step 4 .
2. Check CKP sensor for correct torque and terminal tension. Repair as necessary. If CKP sensor and connections are okay, replace PCM. Perform PCM relearn procedure.
3. Disconnect CKP sensor. Check for continuity between 7X signal high circuit and 7X signal low circuit at CKP sensor harness connector. If continuity is present, repair circuits for short together. If continuity is not present, replace CKP sensor.
4. Disconnect CKP sensor. Check for open in 7X signal high circuit or 7X signal low circuit. Repair as necessary. If circuits are okay, CKP sensor or connections is faulty.

Ignition System Diagnosis

Note. If DTCs P0351, P0352, P1351 or P1352 are set, diagnose these DTCs first. See appropriate SELF-DIAGNOSTICS article.

1. Check for spark at all spark plug wires. If spark is not present on only one wire, replace faulty wire. If spark is not present on 2 wires sharing the same ignition coil, replace faulty ignition coil. If spark is not present at any wire, go to next step.
2. Check EIS fuse (10-amp) located in underhood fuse block. Replace if necessary. Turn ignition on. Disconnect EI module harness connector. Using test light connected to ground, probe ignition feed circuit at EI module harness connector. If test light illuminates, go to next step. If test light does not illuminate, repair open in ignition feed circuit.
3. Using test light connected to battery positive terminal, probe ground circuit at EI module harness connector. If test light illuminates, EI module or connections are faulty. If test light does not illuminate, repair open in ground circuit.

Fuel Delivery Diagnosis

1. Install fuel pressure gauge. See «BASIC FUEL SYSTEM CHECKS»(/buick/lesabre/viii-2000-2005/remont/testing-diagnostics/#engine-control-system-basic-diagnostic-procedures__basic-fuel-system-checks) . Using scan tool, command fuel pump relay on and off for 3 pulses. If fuel pressure is 38-44 psi (2.7-3.1 kg/cm 2 ), fuel quality may be at fault. If fuel pressure is not as specified, go to next step.
2. If fuel pressure is not present, go to next step. If fuel pressure is present but not to specification, diagnose fuel system. See FUEL SYSTEMS in appropriate SYSTEM & COMPONENT TESTING article. Repair as necessary.
3. Turn ignition off for at least 10 seconds. Using test light connected to ground, probe FUEL PUMP fuse (10-amp) located in instrument panel fuse block. Turn ignition on. If test light illuminates for 2 seconds and then turns off, go to next step. If test light does not illuminate, go to step 5 .
4. Check fuel pump battery feed circuit and fuel pump relay ground circuit for open or poor connections. Repair as necessary. If circuits are okay, fuel pump is faulty.
5. Using scan tool, command fuel pump relay on and off. If relay does not click, replace relay. If relay clicks, check I/P BATT fuse (30-amp) located in underhood fuse block. Replace if necessary. If fuse is okay, repair open in fuel pump relay battery feed circuit.

NO START - ENGINE CRANKS OKAY (2.2L & 2.4L - ALERO, CAVALIER, GRAND AM & SUNFIRE)

Note. Before performing the following tests, check battery condition, engine cranking speed and for adequate fuel in tank.

1. Ensure proper starting procedure is being used. Visually check vacuum hoses for splits, kinks and proper connections, as shown on Vehicle Emission Control Information (VECI) label. Check ignition wires for cracking, hardness and proper connections.
2. Remove spark plugs. Check and replace as necessary. In very cold temperatures, ensure oil is proper viscosity and not contaminated with gasoline.

1. If diagnostic system check has already been performed, go to next step. If diagnostic system check has not been performed, go to DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS in appropriate SELF-DIAGNOSTICS article.
2. Turn ignition on, with engine off. Using scan tool, check for DTCs. If DTC P0336, P0601, P0602, P1621 or P1631 is present, diagnose affected DTCs first. See appropriate SELF-DIAGNOSTICS article. If DTCs are not present, go to next step.
3. Attempt to start engine. Using scan tool, monitor the CKP activity counter while the engine is cranking. Does the CKP activity counter increment while cranking the engine? If yes, go to next step. If no, diagnose ignition system. See «BASIC IGNITION SYSTEM CHECKS»(/buick/lesabre/viii-2000-2005/remont/testing-diagnostics/#engine-control-system-basic-diagnostic-procedures__basic-ignition-system-checks) .
4. Turn ignition on, with engine off. Using a test light, probe both sides of the BATT, IGN and F/P-Inj fuses. Does test light illuminate on both sides of all these fuses? If yes, go to next step. If no, check for short to ground in affected circuit. See WIRING DIAGRAMS article.
5. Using scan tool, command fuel pump on. Does fuel pump turn on? If yes, go to next step. If no, go to «FUEL PUMP ELECTRICAL CIRCUIT»(/buick/lesabre/viii-2000-2005/remont/testing-diagnostics/#engine-control-system-basic-diagnostic-procedures__fuel-pump-electrical-circuit) .
6. Turn ignition off. Install a fuel pressure gauge. Turn ignition on, with engine off. Using scan tool, command fuel pump on. Is fuel pressure within 50-60 psi (2.8-4.2 kg/cm 2 ) while fuel pump is operating? If yes, go to next step. If no, go to «FUEL SYSTEM DIAGNOSIS»(/buick/lesabre/viii-2000-2005/remont/testing-diagnostics/#engine-control-system-basic-diagnostic-procedures__fuel-system-diagnosis) .
7. Turn ignition off. Remove ignition coil housing. DO NOT ground ignition coil housing. It may cause erratic spark. Install a jumper wire with clips on both ends from the top of ignition control module to ground. Install Ignition System Diagnostic Harness (J36012-A). Install Spark Tester (J-26792) on cylinder No. 1 spark plug jumper wire. Ground cylinder No. 4 using a spark plug jumper wire. Crank engine with the remaining spark plug jumper wires connected. Repeat this step by installing spark tester on cylinder No. 4 and grounding cylinder No. 1. Do the same for cylinders No. 2 and No. 3 spark plugs. Ensure companion wire is grounded. If spark tester sparks on all cylinders, go to next step. If spark tester does not spark on all cylinders, diagnose ignition system. See «BASIC IGNITION SYSTEM CHECKS»(/buick/lesabre/viii-2000-2005/remont/testing-diagnostics/#engine-control-system-basic-diagnostic-procedures__basic-ignition-system-checks) .
8. Turn ignition off. Disconnect an injector harness connector. Install Injector Test Light (J-34730-405) to injector harness connector. Attempt to start engine. If injector test light blinks while engine is cranking, go to next step. If injector test light does not blink while engine is cranking, diagnose fuel injection system. See FUEL SYSTEMS in appropriate SYSTEM & COMPONENT TESTING article.
9. Inspect for collapsed air intake duct, restricted air filter element, fouled spark plugs, engine mechanical condition (worn timing chain and gears, low compression, etc.), restricted exhaust system or Engine Coolant Temperature (ECT) sensor that is not close to actual engine temperature. See DTC P0117 or P0118 in appropriate SELF-DIAGNOSTICS article. Compare MAP/TP parameters to another vehicle. The parameters should be close in value. Refer DTC P0105 in appropriate SELF-DIAGNOSTICS article. Did you find and correct the condition? If yes, go to next step. If no, problem is intermittent. See TROUBLE SHOOTING - NO CODES article.
10. Using scan tool, clear DTCs. Attempt to start engine. Does engine start and continue to operate? If yes, go to next step. If no, go to step 2 .
11. Operate and warm engine to normal operating temperature. Using scan tool, observe the DTC information. Are any DTCs displayed? If yes, go to appropriate SELF-DIAGNOSTICS article. If no, go to next step.
12. Using scan tool, review the stored information, Capture Info. Does scan tool display any DTCs that have not been diagnosed? If yes, appropriate SELF-DIAGNOSTICS article. If no, system is okay.

Fuel Pump Electrical Circuit

1. If diagnostic system check has already been performed, go to next step. If diagnostic system check has not been performed, go to DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS in appropriate SELF-DIAGNOSTICS article.
2. Connect scan tool. Turn ignition on. Using scan tool, command fuel pump relay on and off. If fuel pump turns on and off, check for intermittent problem. See appropriate TROUBLE SHOOTING - NO CODES article. If fuel pump does not turn on and off, go to next step.
3. Using scan tool, command fuel pump relay on and off. If fuel pump relay clicks, go to step 9 . If fuel pump relay does not click, go to next step.
4. Turn ignition off. Disconnect fuel pump relay located in underhood fuse/relay center. Turn ignition on. Using test light connected to ground, probe fuel pump relay control circuit. Using scan tool, command fuel pump relay on and off. If test light turns on and off, go to next step. If test light does not turn on and off, go to step 6 .
5. Connect test light between fuel pump relay control circuit and fuel pump relay ground circuit. Using scan tool, command fuel pump relay on and off. If test light turns on and off, go to step 19 . If test light does not turn on and off, go to step 22 .
6. If test light remains illuminated, go to next step. If test light does not illuminate at all, go to step 8 .
7. Test the control circuit of fuel pump relay for a short to voltage. Did you find and correct the condition? If yes, go to step 27 . If no, go to step 26 .
8. Test the control circuit of the fuel pump relay 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 .
9. Turn ignition on, with engine off. If fuel pump operates continuously, go to next step. If fuel pump does not operate continuously, go to step 11 .
10. Turn ignition off. Disconnect fuel pump relay. Turn ignition on, with engine off. If fuel pump operates continuously, go to step 21 . If fuel pump does not operate continuously, go to step 25 .
11. Check F/P-INJ fuse (20-amp) located in underhood fuse/relay center. If fuse is open, go to next step. If fuse is okay, go to step 14 .
12. Test the supply voltage circuit of fuel pump for a grounded circuit between fuel pump fuse and fuel pump. Replace fuel pump fuse, if necessary. Did you find and correct the condition? If yes, go to step 27 . If no, go to next step.
13. Install all disconnected electrical components. Install a new fuel pump fuse. Turn fuel pump on with scan tool. Is fuel pump fuse open? If yes, go to step 24 . If no, problem is intermittent.
14. Turn ignition off. Disconnect fuel pump relay, located in underhood fuse/relay center. Turn ignition on, with engine off. Using test light connected to ground, probe fuel pump relay ignition feed circuit at relay cavity. If test light illuminates, go to next step. If test light does not illuminate, go to step 23 .
15. Connect a fused jumper wire between fuel pump relay ignition feed circuit and fuel pump power supply circuit at relay cavities. If fuel pump operates, go to step 19 . If fuel pump does not operate, go to next step.
16. Check fuel pump power supply circuit for open or high resistance between fuel pump relay and rear body harness connector. Repair as necessary. After repairs, go to step 27 . If circuit is okay, go to next step.
17. Check fuel pump ground circuit for open or high resistance between ground and body pass-through harness connector. Repair as necessary. After repairs, go to step 27 . If circuit is okay, go to next step.
18. Check for poor connections at fuel pump. Repair as necessary. After repairs, go to step 27 . If connections are okay, go to step 24 .
19. Inspect for poor connections at fuel pump relay. Did you find and correct the condition? If yes, go to step 27 . If no, go to step 25 .
20. Check for poor connections at PCM. Repair as necessary. After repairs, go to step 27 . If connections are okay, go to step 26 .
21. Repair short to voltage in fuel pump power supply circuit. After repairs, go to step 27 .
22. Repair open in fuel pump relay ground circuit. After repairs, go to step 27 .
23. Repair fuel pump relay ignition feed circuit. After repairs, go to step 27 .
24. Replace fuel pump. After repairs, go to step 27 .
25. Replace fuel pump relay. After repairs, go to step 27 .
26. Replace PCM. Perform PCM relearn procedure. After repairs, go to next step.
27. Operate system to verify repair. If system operation is okay, testing is complete. If system operation is not okay, go to step 2 .

Fuel System Diagnosis

Note. Inspect fuel system for damage or external leaks before proceeding with this diagnostic.

1. If diagnostic system check has already been performed, go to next step. If diagnostic system check has not been performed, go to DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS in appropriate SELF-DIAGNOSTICS article.
2. Turn ignition on, with engine off. Using scan tool, command fuel pump relay on. Does fuel pump operate? If yes, go to next step. If no, go to «FUEL PUMP ELECTRICAL CIRCUIT»(/buick/lesabre/viii-2000-2005/remont/testing-diagnostics/#engine-control-system-basic-diagnostic-procedures__fuel-pump-electrical-circuit) .
3. Turn ignition and all accessories off. Install a fuel pressure gauge. Turn ignition on, with engine off. Fuel pump relay may need to be commanded ON a few times in order to obtain the highest possible fuel pressure. DO NOT start engine. Command fuel pump relay on using scan tool. Observe fuel pressure gauge with fuel pump commanded on. Is fuel pressure within 50-60 psi (3.5-4.2 kg/cm 2 ). If yes, so to next step. If no, go to step 10 .
4. Monitor fuel pressure gauge for one minute. Does fuel pressure decrease by more than 5 psi (0.4 kg/cm 2 ). If yes, go to step 7 . If no, go to next step.
5. Relieve fuel pressure to 10 psi (0.7 kg/cm 2 ). Monitor fuel pressure gauge for 5 minutes. Does fuel pressure decrease by more than 2 psi (0.1 kg/cm 2 )? If yes, go to step 20 . If no, go to next step.
6. Operate vehicle within the conditions to reproduce the original symptoms. Monitor O2 and Fuel Trim parameters with scan tool. Does scan tool parameters indicate a lean condition? If yes, go to step 13 . If no, check for intermittent problem. See appropriate TROUBLE SHOOTING - NO CODES article.
7. Turn ignition off. Remove hose from fuel pressure regulator. Turn ignition on, with engine off. Using scan tool, command fuel pump relay on. Inspect for fuel leak from fuel pressure regulator port. Is fuel pressure regulator leaking fuel? If yes, go to step 19 . If no, go to next step.
8. Turn ignition off. Relieve fuel pressure. Disconnect the chassis fuel hoses from engine compartment fuel pipes. Install Fuel Line Shut-off Adapters (J-37287) between chassis fuel hoses and engine compartment fuel pipes. Open the valves on the fuel pipe shut-off adapters. Turn ignition on, with engine off. Command fuel pump relay on with scan tool. Bleed air from fuel pressure gauge. Command fuel pump relay on and then off with scan tool. Close fuel feed pipe shut-off valve. Monitor fuel pressure gauge for one minute. Does fuel pressure remain constant? If yes, go to step 16 . If no, go to next step.
9. Turn ignition off. Open fuel feed pipe shut-off valve. Turn ignition on, with engine off. Command fuel pump relay on and then off with scan tool. Close fuel return pipe shut-off valve. Monitor fuel pressure gauge for one minute. Does fuel pressure remain constant? If yes, go to step 19 . If no, go to step 17 .
10. Is fuel pressure more than 60 psi (4.2 kg/cm 2 )? If yes, go to next step. If no, go to step 13 .
11. Turn ignition off. Relieve fuel pressure. Disconnect fuel return hose from engine compartment fuel return pipe. Place open end of flexible fuel return hose into an approved gasoline container. Turn ignition on, with engine off. Monitor fuel pressure gauge while fuel pump is operating. Is fuel pressure within 50-60 psi (3.5-4.2 kg/cm 2 )? If yes, go to step 18 . If no, go to next step.
12. Inspect fuel rail return pipe and fuel rail outlet passage for a restriction. Did you find and correct the condition? If yes, go to step 21 . If no, go to step 19 .
13. Turn ignition off. Relieve fuel pressure. Disconnect fuel return hose from engine compartment fuel return pipe. Install Fuel Line Shut-off Adapter (J-37287) between the fuel return hose and engine compartment fuel pipe. Open valve in fuel pipe shut-off adapter. Turn ignition on, with engine off. Bleed air from fuel pressure gauge. Monitor fuel pressure gauge. DO NOT allow fuel pressure to exceed 75 psi (5.27 kg/cm 2 ). Excessive pressure may damage fuel system. Using scan tool, command fuel pump relay on. Slowly close valve in fuel return pipe shut-off adapter, while fuel pump is operating. Does fuel pressure increase to more than 60 psi (4.2 kg/cm 2 )? If yes, go to step 19 . If no, go to next step.
14. Inspect for a restricted fuel filter or fuel feed pipe. Did you find and correct the condition? If yes, go to step 21 . If no, go to next step.
15. Inspect harness connectors and ground circuits of fuel pump for poor connections. Did you find and correct the condition? If yes, go to step 21 . If no, go to next step.
16. Remove fuel sender assembly. Inspect fuel pump flex hose for damage, in-tank fuel pump harness connectors for poor connections, fuel strainer for a restriction or fuel tank for contaminants. Did you find and correct the condition? If yes, go to step 21 . If no, go to step 20 .
17. Open the fuel return pipe shut-off valve. Turn ignition off. Raise fuel rail, with fuel lines connected. Turn ignition on, with engine off. Command fuel pump relay on with scan tool. Locate and replace leaking fuel injector. After repairs, go to step 21 .
18. Repair restricted fuel return pipe. After repairs, go to step 21 .
19. Replace fuel pressure regulator. After repairs, g to step 21 .
20. Replace fuel sender. After repairs, go to next step.
21. Operate the system in order to verify the repair. Did you correct the condition? If yes, system is okay. If no, go to step 3 .

NO START - ENGINE CRANKS OKAY (2.2L - SATURN)

Note. Before performing the following tests, check battery condition, engine cranking speed and for adequate fuel in tank.

1. If diagnostic system check has already been performed, go to next step. If diagnostic system check has not been performed, go to DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS in SELF-DIAGNOSTICS - 2.2L SATURN "L" SERIES article.
2. If any BCM communication or Passlock(R) DTCs (P1630, P1631, P1632, P1626 or U1016) are set, diagnose DTCs first. See SELF-DIAGNOSTICS - 2.2L SATURN "L" SERIES article or appropriate BODY CONTROL MODULES article in ACCESSORIES & EQUIPMENT. If listed DTCs are not set, go to next step.
3. Using scan tool, monitor ignition 1 voltage. If voltage is not less than 2 volts, go to step 5 . If voltage is less than 2 volts, check IGN 1 fuse in underhood fuse block. Replace as necessary. If use is okay, check CONTROLS IGN 1 in underhood fuse block. Replace and retest if fuse is open. If fuse blows again, check for short in circuit between fuse block and PCM. If circuit is okay, go to next step.
4. Turn ignition off. Disconnect PCM harness connector J1. Turn ignition on, with engine off. Using a DVOM, check voltage between PCM harness connector J1 terminal No. 19 (Pink wire) and ground. See WIRING DIAGRAMS article. If ignition voltage is not present, repair open in circuit. If ignition voltage is present, check ground splice for tightness. Check PCM harness connector J1 for terminal tightness. Repair as necessary. If ground connection and PCM harness terminals are okay, replace PCM.
5. If any PCM internal DTCs (P0601, P0602 or P1621) are set, diagnose affected DTC first. See SELF-DIAGNOSTICS - 2.2L SATURN "L" SERIES article. If listed DTCs are not set, go to next step.
6. Using scan tool, monitor CKP ACTIVE COUNTER while cranking engine. If counter is incrementing while cranking engine, go to next step. If counter is not incrementing while cranking engine, go to «NO RPM DETECTED DIAGNOSIS»(/buick/lesabre/viii-2000-2005/remont/testing-diagnostics/#engine-control-system-basic-diagnostic-procedures) .
7. Using scan tool, monitor CALC COMPRESSION OUTPUT while cranking engine. If pattern 00000110 or 00001001 is present, go to next step. If pattern 00000110 or 0001001 is not present, go to «IGNITION DIAGNOSIS»(/buick/lesabre/viii-2000-2005/remont/testing-diagnostics/#engine-control-system-basic-diagnostic-procedures) .
8. Check the 10-amp INJ fuse located in the underhood fuse block. Replace fuse and retest. If fuse blows again when engine is cranked, check for short to ground in circuit between fuse and fuel injectors. See WIRING DIAGRAMS article. If circuit is okay, check for a shorted fuel injector. If injectors are okay, disconnect cylinder No. 4 injector harness connector. Connect a Noid Light (J-34730-405) between cylinder No. 4 harness connector terminals. Crank engine. If Noid light pulses, go to «FUEL DELIVERY DIAGNOSIS»(/buick/lesabre/viii-2000-2005/remont/testing-diagnostics/#engine-control-system-basic-diagnostic-procedures) . If Noid light does not pulse, repair open in cylinder No. 4 injector circuit.

1. Turn ignition off. Disconnect PCM harness connector J2. Using a DVOM, check resistance between PCM harness connector J2 terminals No. 27 (Yellow wire) and No. 28 (Purple wire). See WIRING DIAGRAMS article. Resistance should be 500-900 ohms. If resistance is as specified, check Crankshaft Position (CKP) sensor for correct torque and terminal tightness. If okay, replace PCM. If resistance is less than 500 ohms, go to next step. If resistance is greater than 900 ohms, go to step 3 .
2. Disconnect CKP sensor harness connector. Check continuity between CKP sensor harness connector terminals. If continuity exists, check for shorted CKP sensor circuit between harness connector and PCM. If continuity does not exist, replace CKP sensor.
3. Disconnect CKP sensor harness connector. Check continuity between CKP sensor harness connector terminals. If continuity does not exist, check circuits for open between harness connector and PCM. If continuity exists, check CKP sensor for correct torque and terminal tightness. If okay, replace CKP sensor.

Note. If a specific cylinder misfire is indicated on scan tool, engine is probably flooded. See DTC P0300 in SELF-DIAGNOSTICS - 2.2L SATURN "L" SERIES article for pattern breakdown or combinations.

1. Using scan tool, monitor CALC COMPRESSION OUTPUT while cranking engine. Observe pattern. If pattern 00000011 or 00001100 is observed, diagnose circuit No. 423 (IC No. 1 and 4). go to step 3. If pattern 00001110 or 00000001 is observed, diagnose circuit No. 406 (IC No. 2 and 3), go to step 3. See WIRING DIAGRAMS article. If pattern 000000 is observed, go to next step.
2. Turn ignition off. Remove Electronic Ignition (EI) module from ignition coil housing and disconnect interconnect connector. Turn ignition on, with engine off. Using a test light connected to ground, probe EI module primary ignition coil voltage terminal "D" circuit. (Scheme 1) If test light illuminates, check interconnect connector for tightness. Repair as necessary. If connector is okay, replace ignition coil housing. If test light does not illuminate, replace EI module.
3. Turn ignition off. Remove EI module from ignition coil housing. Ensure interconnect connector is installed and tight. Connect a Noid Light (J34730-2A) between EI module primary ignition coil voltage terminal "D" circuit and EI module interconnect terminal "G" (Orange wire), if testing circuit No. 423 or terminal "B" (White wire), if testing circuit No. 406. (Scheme 1) Crank engine. If Noid light pulses, check for terminal tightness at interconnect to ignition coil housing. Repair as necessary. If terminals are okay, replace ignition coil housing. If Noid light does not pulse, go to next step.
4. Turn ignition off. Disconnect PCM harness connector J2. Turn ignition on, with engine off. Using a test light connected to battery voltage, touch PCM harness connector terminal J2-19 (White wire) or terminal J2-20 (Orange wire). If Noid light pulses when circuit is connected to battery voltage, check for terminal tightness. Repair as necessary. If terminals are okay, replace PCM. If Noid light does not pulse when circuit is connected to battery voltage, go to next step.
5. Check for continuity in circuits No. 406 or 423. See WIRING DIAGRAMS article. If continuity exists, go to next step. If continuity does not exist, repair open in circuit.
6. Check continuity to ground in circuit No. 406 or 423 at EI module harness connector. If continuity does not exist, go to next step. If continuity exists, repair circuit No. 406 or 423 for short to ground.
7. Turn ignition off. Reconnect PCM harness connector. Turn ignition on, with engine off. Check voltage on circuit No. 406 or 423 at EI module harness connector. If voltage is present, check for short in affected circuit. If voltage is not present, check for terminal tightness. Repair as necessary. If terminals are okay, replace EI module.

Scheme 1

1. Install fuel pressure gauge. See «BASIC FUEL SYSTEM CHECKS»(/buick/lesabre/viii-2000-2005/remont/testing-diagnostics/#engine-control-system-basic-diagnostic-procedures__basic-fuel-system-checks). Turn ignition on. If pressure is 50-60 psi (3.5-4.2 kg/cm 2 ), fuel quality or a flooded engine may be cause of problem. If fuel pressure is not as specified, go to next step.
2. If pressure is present but not as specified, diagnose fuel system. See FUEL SYSTEMS in appropriate SYSTEM & COMPONENT TESTING article. If pressure is not present, go to next step.
3. Using scan tool, command fuel pump on and off and listen for clicking at fuel pump relay. Relay is located in underhood fuse block. If relay clicks, go to next step. If relay does not click, go to step 8.
4. Remove fuel pump relay from fuse block. Using a test light connected to ground, probe fuel pump relay control circuit (terminal No. 1140) at relay cavities. (Scheme 2) If test light illuminates, go to next step. If test light does not illuminate, check 15-amp fuel pump fuse, located in underhood fuse block. Replace fuse as necessary and retest. If fuse blows again, check for short to ground in fuel pump relay circuits No. 120 (Gray wire) and No. 1140 (Dark Green/White wire) or for shorted fuel pump motor. If circuits and fuel pump motor are okay, check for open in fuel pump relay control circuit No. 1140 (Dark Green/White wire). See WIRING DIAGRAMS article.
5. Reinstall fuel pump relay. Raise and support vehicle. Disconnect fuel tank 10-pin in-line harness connector. Connect a Noid Light (J34730-405) between harness connector terminals No. 120 (Gray wire) and No. 650 (Black wire). See WIRING DIAGRAMS article. Using scan tool, command fuel pump relay on. If Noid light illuminates, go to next step. If Noid light does not illuminate, go to step 7.
6. Check circuits for open between fuel tank in-line harness connector and fuel tank unit. Check for terminal tightness at harness connector. Repair as necessary. If circuits or terminals are okay, replace fuel pump motor.
7. Connect a test light between ground and fuel tank in-line harness connector circuit No. 120 (Gray wire). Using scan tool, command fuel pump on. If test light illuminates, repair open in circuit No. 650 (Black wire). If test light does not illuminate, repair open in circuit No. 120 (Gray wire) to fuel pump relay.
8. Substitute fuel pump relay with front wiper relay or with known-good relay. Using scan tool, command fuel pump on and off. If relay does not click, go to next step. If relay clicks, check for terminal tightness at fuse block. Repair as necessary. If terminals are okay, replace fuel pump relay.
9. Connect a test light between ground and fuel pump relay terminal No. 465 (Gray wire) in relay cavities. If test light illuminates, repair open in fuel pump relay terminal No. 150 (Gray wire). (Scheme 2) If test light does not illuminate, go to next step.
10. Turn ignition off. Disconnect PCM harness connector J1. Check continuity between fuel pump relay terminal No. 465 (Gray wire) in relay cavities. If continuity exists, repair for short to ground in circuit. If continuity does not exist, go to next step.
11. Check fuel pump relay terminal No. 465 (Gray wire) for open or terminal tightness. Repair as necessary. If circuit or terminal is okay, replace PCM.

Scheme 2

NO START - ENGINE CRANKS OKAY (3.0L - SATURN)

Note. Before performing the following tests, check battery condition, engine cranking speed and for adequate fuel in tank.

1. Ensure vehicle has adequate fuel and cranking speed is normal. Turn ignition off for 10 seconds. Turn ignition on, with engine off. Using scan tool, verify if communications can be established with the BCM and ECM. Check for DTCs. If scan tool communicates with BCM and ECM, go to next step. If scan tool does not communicate with BCM and ECM, diagnose network communications problem. See appropriate BODY CONTROL MODULES article.
2. Check if there are any BCM/ECM PassLock(R) security system or communication DTCs present. If BCM DTCs are not present, go to next step. If BCM DTCs are present, see appropriate BODY CONTROL MODULES article.
3. If ECM DTC P0601, P0602, P0603, P0604 or P0606 is set, diagnose affected DTC(s). See appropriate SELF-DIAGNOSTICS article. If ECM DTC P0601, P0602, P0603, P0604 or P0606 is not set, go to next step.
4. If fuel injector DTCs P0201-P0206 are set. If DTCs P0201-P0206 are not set, go to next step. If DTCs P0201-P0206 are set, check ENG CNTL 2 fuse, located in underhood fuse block. Replace as necessary and retest. If fuse continues to open, check for short on injector circuits. If fuse is okay, repair open in ignition voltage circuit between fuel injectors and underhood fuse block. See WIRING DIAGRAMS article.
5. Check if DTCs P0230, P0231, P0232 or P1403 is set. If any of the DTC is set, diagnose affected DTC(s). See appropriate SELF-DIAGNOSTICS article. If no DTC is set, go to next step.
6. Using scan tool, monitor ENGINE SPEED while cranking engine. If RPM is not detected, diagnose using DTC P0335 diagnostic procedures. See appropriate SELF-DIAGNOSTICS article. If RPM is detected, go to next step.
7. Check if DTC P0341, P0342 or P0343 is set. If any the DTC is set, diagnose affected DTC(s). See appropriate SELF-DIAGNOSTICS article. If no DTC is set, go to next step.
8. Turn ignition on, with engine off. Check IGN fuse in underhood fuse block. Replace as necessary and retest. If fuse continues to open, check for short to ground in ignition circuit. If fuse is okay, go to next step.
9. Using scan tool, perform IGNITION COIL CYL 1-6 test for each individual cylinder while listening closely for spark at appropriate ignition coil. Is spark audible on each cylinder? If yes, go to next step. If no, go to «IGNITION DIAGNOSIS»(/buick/lesabre/viii-2000-2005/remont/testing-diagnostics/#engine-control-system-basic-diagnostic-procedures) .
10. Connect Fuel Pressure Gauge (SA9127E) to test port. Using scan tool, command fuel pump relay on for at least 5 seconds. If fuel pressure is 39-49 psi (2.7-3.4 kg/cm 2 ), go to next step. If fuel pressure is not 39-49 psi (2.7-3.4 kg/cm 2 ), go to «FUEL DELIVERY SYSTEM»(/buick/lesabre/viii-2000-2005/remont/testing-diagnostics/#engine-control-system-basic-diagnostic-procedures__fuel-delivery-system) .
11. Turn ignition on, with engine off. Check for a normal MAF sensor voltage reading (0.8-1.2 volts), a normal closed EGR sensor voltage reading (0.5-1.0 volt) and a normal ECT sensor voltage (based on actual engine temperature). Are the 3 sensor readings within range? If yes, check for fouled spark plugs, restricted air induction, restricted exhaust, cam timing or engine mechanical failure. If no, diagnose affected sensor using appropriate DTC test procedures (MAF - P0101, EGR - P1406 or ECT - P0116).

1. If spark is not present at a specific cylinder, go to next step. If spark is not present on all cylinders on a specific ignition coil, go to step 4 . If spark is not present at all, go to step 6 .
2. Disconnect appropriate ignition control module harness connector. Connect test light between battery positive terminal and ignition coil control circuit in question. Using scan tool, command appropriate ignition coil on. If test light does not illuminate, go to next step. If test light flashes, terminal connections or ignition control module is faulty. If test light remains illuminated, ignition coil control circuit is shorted to ground, or ECM is faulty.
3. Connect test light between ground and ignition coil control circuit in question. If test light illuminates, control circuit is shorted to voltage. If test light does not illuminate, control circuit is open, or terminal connections or ECM is faulty.
4. Turn ignition off. Disconnect appropriate ignition control module harness connector. Turn ignition on. Connect test light between ignition control module ignition feed circuit and ignition control module ground circuit at ignition control module harness connector. If test light illuminates, go to next step. If test light does not illuminate, repair open in ignition feed circuit.
5. Connect test light between engine ground circuit at ignition control module harness connector and battery positive terminal. If test light illuminates, terminal connections or ignition control module are faulty. If test light does not illuminate, repair open in engine ground circuit.
6. Engine ground circuit or IGN fuse (15-amp) is faulty. If fuse is at fault and continues to blow, an ignition control module is shorted to ground. Repair as necessary.

Fuel Delivery System

1. If fuel pressure is present but out of specification, diagnose fuel system. See FUEL SYSTEMS in appropriate SYSTEM & COMPONENT TESTING article. If fuel pressure is not present, check FUEL PUMP fuse (15-amp) located in underhood fuse block. Replace as necessary and retest. If fuse is okay, go to next step. If fuse continuously blows, repair short to ground in fuel pump relay battery feed circuit or fuel pump power feed circuit.
2. Turn ignition on. Remove fuel pump relay located in underhood fuse block. Install a known-good relay, or jumper fuel pump relay battery feed circuit and fuel pump power feed circuit together at relay cavities. Using scan tool, command fuel pump relay on. If fuel pump runs, terminal connections or fuel pump relay are faulty. If fuel pump does not run, go to next step.
3. Connect test light between fuel pump relay ground circuit and fuel pump relay battery feed circuit at relay cavities in fuse block. If test light illuminates, go to next step. If test light does not illuminate, repair open battery feed circuit.
4. Turn ignition on. Connect scan tool. Raise and support vehicle. Disconnect 8-pin fuel tank unit in-line harness connector. Connect test light between fuel pump power feed circuit and fuel pump ground circuit at in-line harness connector (engine side). Using scan tool, command fuel pump relay on. If test light illuminates, terminal connections, fuel pump harness or fuel pump are faulty. Repair as necessary. If test light does not illuminate, go to next step.
5. Connect test light between chassis ground and fuel pump power feed circuit at fuse block. Using scan tool, command fuel pump relay on. If test light illuminates, repair open in fuel pump ground circuit. If test light does not illuminate, repair open in fuel pump battery feed circuit.

NO START - ENGINE CRANKS OKAY (3.1L & 3.4L)

Note. Before performing the following tests, check battery condition, engine cranking speed and for adequate fuel in tank. After fault has been isolated and repairs have been completed, perform diagnostic system check. See DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS in appropriate SELF-DIAGNOSTICS article.

General Inspection (3.1L Century & Malibu)

1. If diagnostic system check has already been performed, go to next step. If diagnostic system check has not been performed, go to DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS in appropriate SELF-DIAGNOSTICS article.
2. Crank engine for 15 seconds. Turn ignition on, with engine off. Using scan tool, observe DTC information. Does scan tool display DTC P0101, P0123, P0230, P0336, P0341, P0601, P0602, P1626, P1630, P1631, U1000, U1064, U1016, B1369 or B1379? If yes, diagnose affected DTC(s). See appropriate SELF-DIAGNOSTICS article. If no, go to next step.
3. Using scan tool, monitor cylinders No. 1-6 injector circuit status parameters. Crank engine. Do all of cylinder injector circuit status parameters display OK? If yes, go to next step. If no, go to «FUEL INJECTOR CIRCUIT DIAGNOSIS (3.1L & 3.4L)»(/buick/lesabre/viii-2000-2005/remont/testing-diagnostics/#engine-control-system-basic-diagnostic-procedures__fuel-injector-circuit-diagnosis-31l) .
4. Using scan tool, command fuel pump on. Does the fuel pump turn on? If yes, go to next step. If no, go to «FUEL PUMP ELECTRICAL CIRCUIT DIAGNOSIS (3.1L CENTURY & GRAND PRIX; 3.4L IMPALA & MONTE CARLO)»(/buick/lesabre/viii-2000-2005/remont/testing-diagnostics/#engine-control-system-basic-diagnostic-procedures__fuel-pump-electrical-circuit-diagnosis-31l) .
5. Turn ignition off. Disconnect a spark plug wire. Install Spark Tester (J-26792) to spark plug wire. Attempt to start engine. Does spark tester spark? If yes, go to next step. If no, go to «BASIC IGNITION SYSTEM CHECKS»(/buick/lesabre/viii-2000-2005/remont/testing-diagnostics/#engine-control-system-basic-diagnostic-procedures__basic-ignition-system-checks) .
6. Turn ignition off. Connect all disconnected components. Install Fuel Pressure Gauge (J-34730-1A). Turn ignition on, with engine off. Using scan tool, command fuel pump on. Is fuel pressure within 52-59 psi (3.7-4.1 kg/cm 2 ) when fuel pump is operating? If yes, go to next step. If no, go to «FUEL SYSTEM DIAGNOSIS (3.1L & 3.4L)»(/buick/lesabre/viii-2000-2005/remont/testing-diagnostics/#engine-control-system-basic-diagnostic-procedures__fuel-system-diagnosis-31l-34l) .
7. Disconnect fuel injector harness multi-way connector. Jumper the 3 Camshaft Position (CMP) sensor circuits between the fuel injector harness multi-way connectors. Probe fuel injector control circuits, PCM side of connector, with a test light connected to battery voltage. Crank engine. Does test light blink while cranking the engine? If yes, go to next step. If no, diagnose using DTC P0341 diagnostic procedures. See appropriate SELF-DIAGNOSTICS article.
8. Inspect for collapsed air intake duct, restricted air filter element, spark plugs for being gas or coolant fouled, engine mechanical condition, restricted exhaust system or Engine Coolant Temperature (ECT) sensor that is not close to actual engine temperature (compare MAP/BARO parameters to another vehicle, parameters should be close in value). Check Throttle Position (TP) sensor for being stuck in range. Did you find and correct the condition? If yes, go to next step. If no, problem is intermittent. Check or compare MAP and TP sensor value to a known-good vehicle. Compare ECT with IAT values on a completely cool engine. The engine coolant temperature should be within 5°F (3°C) of intake air temperature. If not, refer to DTC P0128 diagnostic procedures. See appropriate SELF-DIAGNOSTICS article.
9. Clear DTCs. Attempt to start engine. Does engine start and continue to operate? If yes, go to next step. If no, go to step 2 .
10. Allow engine to reach operating temperature. Observe DTC information with scan tool. Are there any DTCs that have not been diagnosed? If yes, diagnose affected DTC(s). See appropriate SELF-DIAGNOSTICS article. If no, system is okay.

General Inspection (3.1L Grand Prix; 3.4L Alero & Grand Am)

1. If diagnostic system check has already been performed, go to next step. If diagnostic system check has not been performed, go to DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS in appropriate SELF-DIAGNOSTICS article.
2. Turn ignition on, with engine off. Using scan tool, observe the DTC information. Does scan tool displays DTC P0101, P0123, P0230, P0336, P0341, P0601, P0602, P1626, P1630 or P1631? If yes, diagnose affected DTC(s). See appropriate SELF-DIAGNOSTICS article. If no, go to next step.
3. Turn ignition on, with engine off. Ensure that the PCM/IGN fuse is not open. If fuse open? If yes, go to step 11 . If no, go to next step.
4. Attempt to start engine. Using scan tool, observe engine RPM parameter while engine is cranking. Does engine RPM parameter displays cranking RPM ? If yes, go to next step. If no, go to «BASIC IGNITION SYSTEM CHECKS»(/buick/lesabre/viii-2000-2005/remont/testing-diagnostics/#engine-control-system-basic-diagnostic-procedures__basic-ignition-system-checks) .
5. Monitor the cylinders No. 1-6 injector circuit status parameter with scan tool. Crank engine. Do all of the cylinder injector circuit status parameters display OK? If yes, go to next step. If no, go to «FUEL INJECTOR CIRCUIT DIAGNOSIS (3.1L & 3.4L)»(/buick/lesabre/viii-2000-2005/remont/testing-diagnostics/#engine-control-system-basic-diagnostic-procedures__fuel-injector-circuit-diagnosis-31l) .
6. Command fuel pump on with scan tool. Does fuel pump turn on? If yes, go to next step. If no, go to «FUEL PUMP ELECTRICAL CIRCUIT DIAGNOSIS (3.1L MALIBU; 3.4L ALERO & GRAND AM)»(/buick/lesabre/viii-2000-2005/remont/testing-diagnostics/#engine-control-system-basic-diagnostic-procedures__fuel-pump-electrical-circuit-diagnosis-31l) .
7. Turn ignition off. Disconnect a spark plug wire. Install Spark Tester (J-26792) to spark plug wire. Attempt to start engine. Does the spark tester spark? If yes, go to next step. If no, go to «IGNITION SYSTEM DIAGNOSIS (3.1L & 3.4L)»(/buick/lesabre/viii-2000-2005/remont/testing-diagnostics/#engine-control-system-basic-diagnostic-procedures__ignition-system-diagnosis-31l-34l) .
8. Turn ignition off. Install all disconnected components. Install Fuel Pressure Gauge (J-34730-1A). Turn ignition on, with engine off. Using scan tool, command fuel pump on. Is fuel pressure within 52-59 psi (3.7-4.1 kg/cm 2 ) when fuel pump is operating? If yes, go to next step. If no, go to «FUEL SYSTEM DIAGNOSIS (3.1L & 3.4L)»(/buick/lesabre/viii-2000-2005/remont/testing-diagnostics/#engine-control-system-basic-diagnostic-procedures__fuel-system-diagnosis-31l-34l) .
9. Disconnect fuel injector harness multi-way connector. Jumper the 3 Camshaft Position (CMP) sensor circuits between the fuel injector harness multi-way connectors. Probe fuel injector control circuits, PCM side of connector, with a test light connected to battery voltage. Crank engine. Does test light blink while cranking the engine. If yes, go to next step. If no, go to DTC P0341. See appropriate SELF-DIAGNOSTICS article.
10. Inspect for collapsed air intake duct, restricted air filter element, spark plugs for being gas or coolant fouled, engine mechanical condition, restricted exhaust system or Engine Coolant Temperature (ECT) sensor is NOT close to actual engine temperature (compare MAP/BARO parameters to another vehicle, parameters should be close in value). Check TP sensor for being stuck in range. Did you find and correct the condition? If yes, go to step 12 . If no, problem is intermittent. Check or compare MAP and TP sensor value to a known-good vehicle. Compare ECT with IAT values on a completely cool engine. The engine coolant temperature should be within 5°F (3°C) of intake air temperature. If not, refer to DTC P0128 diagnostic procedures. See appropriate SELF-DIAGNOSTICS article.
11. Repair short to ground on circuit supplied by the open fuse. Replace fuse. After repairs, go to next step.
12. Clear DTCs with scan tool. Attempt to start engine. Does engine start and continue to operate? If yes, go to next step. If no, go to step 2 .
13. Operate engine at idle. Allow engine to reach operating temperature. Observe DTC information with a scan tool. Are any DTCs displayed? If yes, diagnose affected DTC(s). See appropriate SELF-DIAGNOSTICS article. If no, go to next step.
14. Using scan tool, observe the stored information, Capture Info. Does scan tool display any DTCs that you have not diagnosed? If yes, diagnose affected DTC. See appropriate SELF-DIAGNOSTICS article. If no, system is okay.

General Inspection (3.4L Impala & Monte Carlo)

1. If diagnostic system check has already been performed, go to next step. If diagnostic system check has not been performed, go to DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS in appropriate SELF-DIAGNOSTICS article.
2. Turn ignition on, with engine off. Using scan tool, observe the DTC information. Does scan tool display DTC P0101, P0123, P0230, P0336, P0341, P0601, P0602, P1626, P1630 or P1631? If yes, diagnose affected DTC(s). See appropriate SELF-DIAGNOSTICS article. If no, go to next step.
3. Turn ignition on, with engine off. Ensure F/P relay, DFI and INJR fuses are okay before proceeding with this test. If any of the fuses are open, go to next step. If fuses are okay, probe both sides of each fuse using a test light. If test light illuminates on at least one side of each of the fuses, go to next step. If test light does not illuminate, go to «IGNITION RELAY DIAGNOSIS (3.1L GRAND PRIX; 3.4L IMPALA & MONTE CARLO ONLY)»(/buick/lesabre/viii-2000-2005/remont/testing-diagnostics/#engine-control-system-basic-diagnostic-procedures__ignition-relay-diagnosis-31l-grand-prix) .
4. Using scan tool, monitor the cylinders No. 1-6 injector circuit status parameters. Crank engine. Do all of the cylinder injector circuit status parameters display OK? If yes, go to next step. If no, go to «FUEL INJECTOR CIRCUIT DIAGNOSIS (3.1L & 3.4L)»(/buick/lesabre/viii-2000-2005/remont/testing-diagnostics/#engine-control-system-basic-diagnostic-procedures__fuel-injector-circuit-diagnosis-31l) .
5. Using scan tool, command fuel pump on. Does the fuel pump turn on? If yes, go to next step. If no, go to «FUEL PUMP ELECTRICAL CIRCUIT DIAGNOSIS (3.1L CENTURY & GRAND PRIX; 3.4L IMPALA & MONTE CARLO)»(/buick/lesabre/viii-2000-2005/remont/testing-diagnostics/#engine-control-system-basic-diagnostic-procedures__fuel-pump-electrical-circuit-diagnosis-31l) .
6. Turn ignition off. Disconnect a spark plug wire. Install Spark Tester (J-26792) to spark plug wire. Attempt to start engine. Does the spark tester spark? If yes, go to next step. If no, go to «BASIC IGNITION SYSTEM CHECKS»(/buick/lesabre/viii-2000-2005/remont/testing-diagnostics/#engine-control-system-basic-diagnostic-procedures__basic-ignition-system-checks) .
7. Turn ignition off. Connect all disconnected components. Install Fuel Pressure Gauge (J-34730-1A). Turn ignition on, with engine off. Using scan tool, command fuel pump on. Is fuel pressure within 52-59 psi (3.7-4.1 kg/cm 2 ) when fuel pump is operating? If yes, go to next step. If no, go to «FUEL SYSTEM DIAGNOSIS (3.1L & 3.4L)»(/buick/lesabre/viii-2000-2005/remont/testing-diagnostics/#engine-control-system-basic-diagnostic-procedures__fuel-system-diagnosis-31l-34l) .
8. Disconnect fuel injector harness multi-way connector. Jumper the 3 Camshaft Position (CMP) sensor circuits between the fuel injector harness multi-way connectors. Probe the fuel injector control circuits, PCM side of connector, with a test light connected to battery voltage. Crank engine. Does test light blink while cranking the engine? If yes, go to next step. If no, diagnose DTC P0341. See appropriate SELF-DIAGNOSTICS article.
9. Inspect for collapsed air intake duct, restricted air filter element, spark plugs for being gas or coolant fouled, engine mechanical condition, restricted exhaust system or Engine Coolant Temperature (ECT) sensor is NOT close to actual engine temperature (compare MAP/BARO parameters to another vehicle, parameters should be close in value). Check TP sensor for being stuck in range. Did you find and correct the condition? If yes, go to next step. If no, problem is intermittent. Check or compare MAP and TP sensor value to a known-good vehicle. Compare ECT with IAT values on a completely cool engine. The engine coolant temperature should be within 5°F (3°C) of intake air temperature. If not, refer to DTC P0128 diagnostic procedures. See appropriate SELF-DIAGNOSTICS article.
10. Using scan tool, clear DTCs. Attempt to start the engine. Does engine start and continue to operate? If yes, go to next step. If no, go to step 2 .
11. Operate engine at idle. Allow engine to reach operating temperature. With scan tool, observe the DTC information. Are any DTCs displayed? If yes, diagnose affected DTC(s). See appropriate SELF-DIAGNOSTICS article. If no, go to next step.
12. Using scan tool, review the stored information, Capture Info. Does scan tool display any DTCs that you have not diagnosed? If yes, diagnose affected DTC(s). See appropriate SELF-DIAGNOSTICS article. If no, system is okay.

Ignition Relay Diagnosis (3.1L Grand Prix; 3.4L Impala & Monte Carlo Only)

1. If diagnostic system check has already been performed, go to next step. If diagnostic system check has not been performed, go to DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS in appropriate SELF-DIAGNOSTICS article.
2. Turn ignition off. Remove IGN relay located in underhood fuse/relay block. Using a test light connected to ground, probe the IGN relay battery positive voltage circuit at underhood fuse relay center. See WIRING DIAGRAMS article. If test light illuminates, go to next step. If test light does not illuminate, go to step 8 .
3. Turn ignition on, with engine off. Probe IGN relay ignition run/crank voltage circuit at the underhood fuse/relay block with test light connected to a known-good ground. Does test light illuminate? If yes, go to next step. If no, go to step 9 .
4. Turn ignition on, with engine off. Probe ignition main relay ground connector terminal, with test light connected to battery voltage. Does test light illuminate? If yes, go to next step. If no, go to step 10 .
5. Turn ignition off. Jumper IGN relay battery positive voltage circuit and IGN relay load circuit together using a fused jumper wire. Using a test light connected to ground, probe F/INJR, ENG EMIS and OXY SEN fuses, located in underhood fuse/relay block. Does test light illuminate? If yes, go to next step. If no, go to step 10 .
6. Check for poor terminal contact at IGN relay underhood fuse/relay block connector. Did you find and correct the condition? If yes, go to step 11 . If no, go to next step.
7. Replace IGN relay. After replacing relay, go to step 11 .
8. Repair open or short to ground in battery positive voltage supply to IGN relay. After repairs, go to step 11 .
9. Repair ignition positive voltage circuit to IGN relay. After repairs, go to step 11 .
10. Replace underhood fuse/relay block. After replacing fuse/relay block, go to next step.
11. Remove all test equipment. Connect any disconnected components, fuses, etc. Turn ignition off for 30 seconds. Start engine and operate vehicle. Observe the MIL, vehicle performance and driveability. Does vehicle operate normally, with no MIL illumination and no stored DTCs? If yes, system is okay. If no, diagnose affected DTC(s). See appropriate SELF-DIAGNOSTICS article.

Fuel Injector Circuit Diagnosis (3.1L & 3.4L)

1. If diagnostic system check has already been performed, go to next step. If diagnostic system check has not been performed, go to DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS in appropriate SELF-DIAGNOSTICS article.
2. Are any injector DTCs set? If yes, diagnose using DTC P0201-P0206 diagnostic procedure. See appropriate SELF-DIAGNOSTICS article. If no, go to next step.
3. Inspect fuel injector fuse. Is fuse open? If yes, go to next step. If no, go to step 6 .
4. Turn ignition off. Disconnect multi-way harness connector of the fuel injectors. Using a test light connected to battery voltage, probe the ignition 1 voltage circuit of the fuel injector (fuse side). Does test light illuminate? If yes, go to step 9 . If no, go to next step.
5. Turn ignition on, with engine off. Does test light illuminate? If yes, go to step 13 . If no, go to step 8 .
6. Turn ignition off. Disconnect the fuel injector multi-way harness connector. Turn ignition on, with engine off. Probe the ignition 1 voltage circuit of the fuel injector, fuse side, with a test light connected to a known-good ground. Does test light illuminate? If yes, go to next step. If no, go to step 10 .
7. Using a DVOM, check resistance between the ignition voltage terminal and fuel injector harness connector terminal at the multi-way harness connector. If resistance is greater than 5 ohms, go to step 11 . If no, go to step 12 .
8. Test the ignition 1 voltage circuit of the fuel injector, between the multi-way harness connector and fuel injectors for a short to ground. Did you find and correct the condition? If yes, go to step 14 . If no, problem is intermittent.
9. Repair short to ground in ignition voltage circuit of fuel injector. After repairs, go to step 14 .
10. Repair open in ignition 1 voltage between underhood fuse/relay block and multi-way connector. See WIRING DIAGRAMS article. After repairs, go to step 14 .
11. Repair the ignition 1 voltage circuit of the fuel injectors for an open and/or high resistance between the multi-way connector and splice. After repairs, go to step 14 .
12. Repair poor connection at the multi-way connector. After repairs, go to step 14 .
13. Repair short to a PCM ground in ignition voltage circuit of fuel injector. After repairs, go to next step.
14. Operate the system in order to verify the repair. Did you correct the condition? If yes, system is okay. If no, go to step 3 .

Fuel Pump Electrical Circuit Diagnosis (3.1L Century & Grand Prix; 3.4L Impala & Monte Carlo)

1. If diagnostic system check has already been performed, go to next step. If diagnostic system check has not been performed, go to DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS in appropriate SELF-DIAGNOSTICS article.
2. Install scan tool. Turn ignition on, with engine off. Using scan tool, command fuel pump relay on and off. Does the fuel pump turn on and off? If yes, problem is intermittent. If no, go to next step.
3. Using scan tool, command fuel pump relay on and off. Do you hear a click when you command fuel pump relay on and off? If yes, go to step 9 . If no, go to next step.
4. Turn ignition off. Disconnect fuel pump relay. Turn ignition on, with engine off. Probe the control circuit of the fuel pump relay with a test light connected to a good ground. See WIRING DIAGRAMS article. With scan tool, command fuel pump relay on and off. Does test light turn on and off? If yes, go to next step. If yes, go to step 6 .
5. Connect test light between the control circuit of the fuel pump relay and ground circuit of fuel pump relay. With scan tool, command fuel pump relay on and of. Does test light turn on and off? If yes, go to step 19 . If no, go to step 22 .
6. Does test light remain illuminated with each command? If yes, go to next step. If no, go to step 8 .
7. Test the control circuit of the fuel pump relay for a short to voltage. Did you find and correct the condition? If yes, go to step 27 . If no, go to step 26 .
8. Test the control circuit of the fuel pump relay 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 .
9. Turn ignition on, with engine off. Does fuel pump operate continuously? If yes, go to next step. If no, go to step 11 .
10. Turn ignition off. Disconnect fuel pump relay. Turn ignition on, with engine off. Does fuel pump operate continuously? If yes, go to step 21 . If no, go to step 25 .
11. Is the fuel pump fuse open? If yes, go to next step. If no, go to step 14 .
12. Test the supply voltage circuit of the fuel pump for a grounded circuit between the fuel pump fuse and the fuel pump. See WIRING DIAGRAMS article. Replace fuel pump fuse if necessary. Did you find and correct the condition? If yes, go to step 27 . If no, go to next step.
13. Install all disconnected electrical components. Install a new fuel pump fuse. Using scan tool, turn on fuel pump relay. Inspect fuel pump fuse. Is fuel pump fuse open? If yes, go to step 24 . If no, problem is intermittent.
14. Turn ignition off. Disconnect fuel pump relay. Turn ignition on, with engine off. Probe the battery voltage circuit of the fuel pump relay switch with test light connected to a good ground. Does test light illuminate? If yes, go to next step. If no, go to step 23 .
15. Connect a 20-amp fused jumper wire between the battery voltage circuit of the fuel pump relay switch and the supply voltage circuit of the fuel pump. Does the fuel pump operate? If yes, go to step 19 . If no, go to next step.
16. Test the supply voltage circuit of the fuel pump for an open or high resistance between fuel pump relay and fuel pump. Did you find and correct the condition? If yes, go to step 27 . If no, go to next step.
17. Inspect ground circuit for tightness, corrosion on terminals, or damage to wiring harness. Test ground circuit of 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.
18. Inspect for poor connections at fuel pump. Did you find and correct the condition? If yes, go to step 27 . If no, go to step 24 .
19. Inspect for poor connections at fuel pump relay. Did you find and correct the condition? If yes, go to step 27 . If no, go to step 25 .
20. Inspect for poor connections at PCM harness connector. Did you find and correct the condition? If yes, go to step 27 . If no, go to step 26 .
21. Repair supply voltage circuit of fuel pump for a short to voltage. After repairs, go to step 27 .
22. Repair open fuel pump relay ground circuit. After repairs, go to step 27 .
23. Repair battery voltage circuit of the fuel pump relay switch. After repairs, go to step 27 .
24. Replace fuel pump. Replace fuel pump fuse if necessary. After repairs, go to step 27 .
25. Replace fuel pump relay. After repairs, go to step 27 .
26. Replace PCM. After replacing PCM, go to next step.
27. Operate the system in order to verify the repair. Did you correct the condition? If yes, system is okay. If no, go to step 2 .

Fuel Pump Electrical Circuit Diagnosis (3.1L Malibu; 3.4L Alero & Grand Am)

1. If diagnostic system check has already been performed, go to next step. If diagnostic system check has not been performed, go to DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS in appropriate SELF-DIAGNOSTICS article.
2. Install scan tool. Turn ignition on, with engine off. Using scan tool, command fuel pump relay on and off. Does fuel pump turn on and off? If yes, problem is intermittent. If no, go to next step.
3. Command fuel pump relay on and off with scan tool. Do you hear a click when you command the fuel pump relay on and off? If yes, go to step 9 . If no, go to next step.
4. Turn ignition off. Disconnect fuel pump relay. Turn ignition on, with engine off. Probe control circuit of the fuel pump relay with a test light connected to a good ground. See WIRING DIAGRAMS article. Command fuel pump on and off with scan tool. Does test light turn on and off? If yes, go to next step. If no, go to step 6 .
5. Connect test light between the control circuit of the fuel pump relay and ground circuit of fuel pump relay. Command fuel pump on and off with a scan tool. Does test light turn on and off? If yes, go to step 21 . If no, go to step 24 .
6. Does the test light remain illuminated with each command? If yes, go to next step. If no, go to step 8 .
7. Test the control circuit of the fuel pump relay for a short to voltage. Did you find and correct the condition? If yes, go to step 29 . If no, go to step 28 .
8. Test the control circuit of the fuel pump relay for a short to ground or an open. Did you find and correct the condition? If yes, go to step 29 . If no, go to step 22 .
9. Turn ignition on, with engine off. Does the fuel pump operate continuously? If yes, go to next step. If no, go to step 11 .
10. Turn ignition off. Disconnect fuel pump relay. Turn ignition on, with engine off. Does fuel pump operate continuously? If yes, go to step 23 . If no, go to step 27 .
11. Is the FP-INJ fuse open? If yes, go to next step. If no, go to step 14 .
12. Disconnect fuel pump harness in-line connector located near fuel tank. Test the supply voltage circuit of fuel pump and the fuel injectors for a grounded circuit. Replace the FP-INJ fuse if necessary. Did you find and correct the condition? If yes, go to step 29 . If no, go to next step.
13. Lower the fuel tank, if necessary. Test or inspect the fuel tank electrical harness for damage to harness or a grounded circuit. Replace the FP-INJ fuse, if necessary. Did you find and correct the condition? If yes, go to step 29 . If no, go to step 20 .
14. Turn ignition off. Disconnect fuel pump relay. Turn ignition on, with engine off. Probe the ignition 1 voltage circuit of the fuel pump relay with a test light connected to a good ground. Does test light illuminate? If yes, go to next step. If no, go to step 25 .
15. Connect a 10-amp fused jumper wire between the ignition 1 voltage circuit and fuel pump supply voltage circuit in fuel pump cavity. Does the fuel pump operate? If yes, go to step 21 . If no, go to next step.
16. Disconnect fuel pump harness in-line connector located near fuel tank. Test the supply voltage circuit of fuel pump for an open or high resistance between fuel pump relay and in-line connector. Did you find and correct the condition? If yes, go to step 29 . If no, go to next step.
17. Ensure ground circuit is tight. Check for corrosion on terminals or damage to wiring harness. Check ground circuit of the fuel pump for an open or high resistance between the body pass-through connector and ground. Did you find and correct the condition? If yes, go to step 29 . If no, go to next step.
18. Inspect for poor connections at fuel pump in-line connector to body pass-through connector. Did you find and correct the condition? If yes, go to step 29 . If no, go to next step.
19. Lower fuel tank. Test or inspect fuel tank electrical harness for damage to harness or an open circuit. Did you find and correct the condition? If yes, go to step 29 . If no, go to step 26 .
20. Connect all disconnected components. Install a new fuel pump fuse. Command the fuel pump on with scan tool. Is fuel pump fuse open? If yes, go to step 26 . If no, problem is intermittent.
21. Inspect for poor connections at fuel pump relay. Did you find and correct the condition? If yes, go to step 29 . If no, go to step 27 .
22. Inspect for poor connections at PCM harness. Did you find and correct the condition? If no, go to step 29 . If no, go to step 28 .
23. Repair supply voltage circuit of fuel pump for a short to voltage. After repairs, go to step 29 .
24. Repair fuel pump relay ground circuit for an open ground. After repairs, go to step 29 .
25. Repair the ignition 1 voltage circuit of the fuel pump relay for an open circuit. After repairs, go to step 29 .
26. Replace fuel pump. Replace fuel pump fuse if necessary. After repairs, go to step 29 .
27. Replace fuel pump relay. After replacing relay, go to step 29 .
28. Replace PCM. After replacing PCM, go to next step.
29. Operate the system in order to verify the repair. Did you correct the condition? If yes, system is okay. If no, go to step 2 .

Fuel System Diagnosis (3.1L & 3.4L)

1. If diagnostic system check has already been performed, go to next step. If diagnostic system check has not been performed, go to DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS in appropriate SELF-DIAGNOSTICS article.
2. Turn ignition on, with engine off. Using scan tool, command fuel pump on. Does fuel pump operate? If yes, go to next step. If no, go to «FUEL PUMP ELECTRICAL CIRCUIT DIAGNOSIS (3.1L CENTURY & GRAND PRIX; 3.4L IMPALA & MONTE CARLO)»(/buick/lesabre/viii-2000-2005/remont/testing-diagnostics/#engine-control-system-basic-diagnostic-procedures__fuel-pump-electrical-circuit-diagnosis-31l) or «FUEL PUMP ELECTRICAL CIRCUIT DIAGNOSIS (3.1L MALIBU; 3.4L ALERO & GRAND AM)»(/buick/lesabre/viii-2000-2005/remont/testing-diagnostics/#engine-control-system-basic-diagnostic-procedures__fuel-pump-electrical-circuit-diagnosis-31l) .
3. Ensure there is adequate fuel in fuel tank. Turn ignition off. Turn off all accessories. Install Fuel Pressure Gauge (J-34730-1A) and fuel pressure gauge fitting. Turn ignition on, with engine off. Command the fuel pump relay on with scan tool. Fuel pump will run for about 2 seconds. Command fuel pump relay on with scan tool in order to obtain the highest possible fuel pressure. DO NOT start engine. Observe fuel gauge, with fuel pump relay commanded on. Is fuel pressure within 52-59 psi (3.7-4.1 kg/cm 2 ). If yes, go to next step. If no, go to step 12 .
4. Monitor fuel pressure gauge for one minute. Does fuel pressure decrease by more than 5 psi (0.4 kg/cm 2 ). If yes, go to step 9 . If no, go to next step.
5. Relieve fuel pressure to 10 psi (0.7 kg/cm 2 ). Monitor fuel pressure gauge for 5 minutes. Does fuel pressure decrease by more than 2 psi (0.1 kg/cm 2 )? If yes, go to step 24 . If no, go to next step.
6. Turn ignition off for 15 seconds. Turn ignition on, with engine off. Monitor the fuel pressure gauge. Start engine. Does the fuel pressure decrease by 3-10 psi (0.2-0.7 kg/cm 2 ) when engine is started? If yes, go to next step. If no, go to step 8 .
7. Operate vehicle within the conditions of the customer's concern. Using scan tool, monitor fuel trim and HO2S parameters. Do any of the scan tool parameters indicate a lean condition? If yes, go to step 17 . If no, problem is intermittent.
8. Disconnect vacuum hose from fuel pressure regulator. Monitor fuel pressure gauge. Operate engine at idle. Using a hand-held vacuum pump, apply 12-14 in. Hg (41-47 kPa) to fuel pressure regulator. Does fuel pressure decrease by 3-10 psi (0.2-0.7 kg/cm 2 ) when vacuum is applied? If yes, go to step 21 . If no, go to step 23 .
9. Turn ignition off. Remove vacuum hose from fuel pressure regulator. Turn ignition on, with engine off. Command fuel pump on with scan tool. Inspect for fuel leak at fuel pressure regulator vacuum port. Is fuel pressure regulator leaking fuel? If yes, go to step 23 . If no, go to next step.
10. Turn ignition off. Relieve fuel pressure. Disconnect fuel feed hose and fuel return hose from fuel rail pipes. Install Fuel Pipe Line Shut-Off Adapters (J-37287) between the fuel hoses and fuel rail pipes. Open the valves on the adapters. Turn ignition on, with engine off. Using scan tool, command fuel pump relay on. Bleed air from fuel pressure gauge. Close fuel feed pipe shut-off valve. Command fuel pump relay on with a scan tool in order to obtain the highest possible fuel pressure. Monitor fuel pressure gauge for one minute. Does the fuel pressure remain constant? If yes, go to step 19 . If no, go to next step.
11. Turn ignition off. Open fuel feed pipe shut-off valve. Turn ignition on, with engine off. Command fuel pump relay on and then off with scan tool. Close fuel return pipe shut-off valve. Monitor fuel pressure gauge for one minute. Does the fuel pressure remain constant? If yes, go to step 23 . If no, go to step 20 .
12. Is fuel pressure greater than 59 psi (4.1 kg/cm 2 )? If yes, go to step 14 . If no, go to next step.
13. Is fuel pressure greater than zero psi? If yes, go to step 16 . If no, go to step 17 .
14. Turn ignition off. Relieve fuel pressure. Disconnect fuel return hose from fuel rail return pipe. Attach a length of flexible fuel hose to fuel rail outlet passage. Place the open end of fuel hose into an approved gasoline container. Turn ignition on, with engine off. Monitor fuel pressure gauge while fuel pump is operating. Is fuel pressure within 52-59 psi (3.7-4.1 kg/cm 2 )? If yes, go to step 22 . If no, go to next step.
15. Inspect fuel rail return pipe and fuel rail outlet passage for a restriction. Did you find and correct the condition? If yes, go to step 25 . If no, go to step 23 .
16. Turn ignition off. Relieve fuel pressure. Disconnect fuel return hose from fuel rail return pipe. Install Fuel Pipe Shut-Off Adapters (J-37287) between fuel return pipe and fuel rail. Open shut-off adapter valve. Turn ignition on, with engine off. Bleed air from fuel system. Monitor fuel pressure gauge. DO NOT allow fuel pressure to exceed 75 psi (5.3 kg/cm 2 ). Excessive pressure may damage the fuel system. Slowly close valve in fuel return pipe shut-off adapter. Command fuel pump relay on with scan tool. Does the fuel pressure increase to greater than 52 psi (3.7 kg/cm 2 ). If yes, go to step 23 . If no, go to next step.
17. Check fuel filter and fuel feed pipe for restriction. Did you find and correct the condition? If yes, go to step 25 . If no, go to next step.
18. Inspect the harness connectors and ground circuits of the fuel pump for poor connections. Did you find and correct the condition? If yes, go to step 25 . If no, go to next step.
19. Remove fuel sender assembly. Inspect fuel pump flex hose for damage, in-tank fuel pump harness connectors for poor connections, fuel strainer for a restriction or for contaminates in fuel tank. Did you find and correct the condition? If yes, go to step 25 . If no, go to step 24 .
20. Turn ignition off. Raise fuel rail with fuel lines connected. Turn ignition on, with engine off. Command fuel pump relay on with scan tool. Locate and replace leaking fuel injector. After replacing injector, go to step 25 .
21. Repair vacuum source to fuel pressure regulator. After repairs, go to step 25 .
22. Locate and repair the restricted fuel return line. After repairs, go to step 25 .
23. Replace fuel pressure regulator. After replacing fuel pressure regulator, go to step 25 .
24. Replace fuel pump. After replacing fuel pump, go to next step.
25. Operate the system in order to verify the repair. Did you correct the condition? If yes, system is okay. If no, go to step 3 .

Ignition System Diagnosis (3.1L & 3.4L)

1. If diagnostic system check has already been performed, go to next step. If diagnostic system check has not been performed, go to DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS in appropriate SELF-DIAGNOSTICS article.
2. Attempt to start engine. Does engine start and continue to run? If yes, problem is intermittent. If no, go to next step.
3. Disconnect the 24X crank sensor (sensor is located behind harmonic balancer). Crank engine. Using scan tool, observe the 3X crank sensor parameter. Does scan tool indicate 3X crank sensor signal is present? If yes, go to next step. If no, go to step 11 .
4. Reconnect the 24X crank sensor. Test for spark at each cylinder using Spark Tester (J-26792). Did you observe any non-sparking cylinders? If yes, go to next step. If no, go to step 8 .
5. Inspect and test the affected cylinder spark plug wires, ignition coils and spark plugs for a short to ground or an arcing to ground. If carbon tracking or corrosion is present, replace both components that are affected. Did you find and correct the condition? If yes, go to step 23 . If no, go to next step.
6. Test affected spark plug wires for proper resistance. Replace spark plug wires not near specification. Did you find and correct the condition? If yes, go to step 23 . If no, go to next step.
7. Switch the affected cylinder coil with a known-good one. If fault follows the affected coil, then replace coil. Did you find and correct the condition? If yes, go to step 23 . If no, go to step 15 .
8. Inspect spark plug wires for proper routing and for correct firing order. Reroute as necessary. Did you find and correct the condition? If yes, go to step 23 . If no, go to next step.
9. Using DVOM, check spark plugs for internal short to ground. Replace any grounded spark plugs. Did you find and correct the condition? If yes, go to step 23 . If no, go to next step.
10. Remove spark plugs. Inspect spark plugs for damage. Replace affected spark plugs. After replacing spark plugs, go to step 23 . If spark plugs are okay, go to next step.
11. Reconnect the 24X crank sensor. Disconnect the IC module harness connectors. Turn ignition on. Using a test light connected to a good ground, probe the IC module ignition 1 voltage circuit. Does the test light illuminate? If yes, go to next step. If no, go to step 17 .
12. Connect a test light between the IC module ignition 1 voltage circuit and IC module ground circuit. Does the test light illuminate? If yes, go to next step. If no, go to step 20 .
13. Disconnect the 7X crank sensor connector from the IC module. With a test light connected to battery voltage, probe both the 7X crank sensor 1 signal and low reference circuits. Does test light illuminate when probing either circuits? If yes, go to step 18 . If no, go to next step.
14. Connect test light to ground. Probe the 7X crank sensor 1 signal and reference low circuits. Does test light illuminate when probing either circuits? If yes, go to step 19 . If no, go to next step.
15. Ensure battery voltage is within specifications. Turn ignition off. Connect DVOM between 7X crank sensor 1 signal circuit and low reference circuit at IC module harness connector. Crank engine while observing AC duty cycle percent. Does the DVOM indicate an AC duty cycle present? If yes, go to step 21 . If no, go to next step.
16. Test the 7X crank sensor circuits for open circuit. Check 7X crank sensor 1 signal and low reference circuits that are shorted together. Repair any damaged wiring. Did you find and correct the condition? If yes, go to step 23 . If no, go to step 22 .
17. Repair open or short to ground in IC module ignition 1 voltage circuit. Replace fuse if necessary. After repairs, go to step 23 .
18. Repair short to ground in circuit which illuminated the test light. After repairs, go to step 23 .
19. Repair short to voltage in circuit which illuminated the test light. After repairs, go to step 23 .
20. Repair open in IC module ground circuit. After repairs, go to step 23 .
21. Replace IC module. After replacing module, go to step 23 .
22. Replace the 7X crank sensor (located on lower right of engine block). After repairs, go to next step.
23. Remove all test equipment. Connect any disconnected components or any disconnected fuses. Turn ignition off for 30 seconds. Start engine and operate vehicle. Observe MIL, vehicle performance and driveability. Does vehicle operate correctly, without any MIL illumination and without any stored DTCs? If yes, system is okay. If no, diagnose affected DTC(s). See appropriate SELF-DIAGNOSTICS article.

1. If diagnostic system check has already been performed, go to next step. If diagnostic system check has not been performed, go to DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS under DIAGNOSTIC SYSTEM CHECKS in appropriate SELF-DIAGNOSTICS article.
2. Turn ignition on, with engine off. Using scan tool, observe DTC information. Does scan tool display DTC P0201-P0208, P0230, P0335, P0340, P0385, P0403, P0404, P0601, P0602, P1359, P1360 or P1404? If yes, diagnose affected DTC(s). See appropriate SELF-DIAGNOSTICS article. If no DTC(s) are set, go to next step.
3. Inspect the fuse that supplies ignition voltage to the ignition coil cassettes. Is fuse open? If yes, go to «BASIC IGNITION SYSTEM CHECKS»(/buick/lesabre/viii-2000-2005/remont/testing-diagnostics/#engine-control-system-basic-diagnostic-procedures__basic-ignition-system-checks) . If no, go to next step.
4. Using scan tool, command fuel pump on. Does fuel pump turn on? If yes, go to next step. If no, go to «FUEL PUMP ELECTRICAL CIRCUIT DIAGNOSIS»(/buick/lesabre/viii-2000-2005/remont/testing-diagnostics/#engine-control-system-basic-diagnostic-procedures__fuel-pump-electrical-circuit-diagnosis) .
5. Turn ignition off. Install Fuel Pressure Gauge (J-34730-1A). Turn ignition on, with engine off. Using scan tool, command the fuel pump on. Is fuel pressure within 48-55 psi (3.4-3.9 kg/cm 2 ) while fuel pump is operating? If yes, go to next step. If no, go to «FUEL SYSTEM DIAGNOSIS»(/buick/lesabre/viii-2000-2005/remont/testing-diagnostics/#engine-control-system-basic-diagnostic-procedures) .
6. Turn ignition off. Disconnect an injector connector from each cylinder bank. Install an injector test light to the injector connector. Attempt to start engine. Does the test light blink while engine is cranking? If yes, go to next step. If no, diagnose using DTC P0201-P0206 test procedures. See appropriate SELF-DIAGNOSTICS article.
7. Check the following: Check for collapsed air intake duct. Check for restricted air filter element. Check spark plugs for being gas or coolant fouled. If spark plugs are fouled, determine cause of condition. Check engine mechanical condition, such as worn timing chain and gears, low compression, etc. Check for restricted exhaust system. If any problems are found, repair as necessary. After repairs, go to next step. If no problems are found, see «DIAGNOSTIC AIDS»(/buick/lesabre/viii-2000-2005/remont/testing-diagnostics/#engine-control-system-basic-diagnostic-procedures__diagnostic-aids) .
8. Using scan tool, clear DTCs. Attempt to start engine. If engine starts and continues to run, go to next step. If engine does not start, go to step 2 .
9. Allow engine to idle. Ensure engine is at normal operating range. Using scan tool, observe DTC information. If any DTCs are set, diagnose affected DTCs. See appropriate SELF-DIAGNOSTICS article. If no DTCs are set, go to next step.
10. Using scan tool, observe stored information and Capture Info. If scan tool displays any undiagnosed DTCs, diagnose affected DTC(s) as necessary. See appropriate SELF-DIAGNOSTICS article. If scan tool does not display any DTCs, system is okay.

Scheme 3

1. If diagnostic system check has already been performed, go to next step. If diagnostic system check has not been performed, go to DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS under DIAGNOSTIC SYSTEM CHECKS in appropriate SELF-DIAGNOSTICS article.
2. Turn ignition on. Using scan tool, command fuel pump relay on and off. If fuel pump relay turns on and off as commanded, no problem is indicated at this time. Fault may be intermittent. If fuel pump relay does not turn on and off as commanded, go to next step.
3. Using scan tool, command fuel pump relay on and off. Listen for fuel pump relay operating click noise. Fuel pump relay is located in rear fuse block. Rear fuse block is located underneath driver's side rear seat. If fuel pump relay operating noise is heard as relay is commanded on and off, go to step 9. If fuel pump relay operating noise is not heard as relay is commanded on and off, go to next step.
4. Turn ignition off. Remove fuel pump relay. Turn ignition on. Using a test light connected to ground, probe fuel pump relay control circuit at fuel pump relay connector in rear fuse block. See WIRING DIAGRAMS article. Using scan tool, command fuel pump relay on and off. If test light turns on and off as commanded, disconnect test light and go to next step. If test light does not turn on and off as commanded, go to step 6.
5. Turn ignition off. Connect a test light between fuel pump relay control circuit and fuel pump relay ground circuit at fuel pump relay connector in rear fuse block. Turn ignition on. Using scan tool, command fuel pump relay on and off. If test light turns on and off as commanded, go to step 21. If test light does not turn on and off as commanded, go to step 24.
6. If test light is always on, go to next step. If test light is always off, go to step 8.
7. Turn ignition off. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Using a test light connected to ground, probe terminal No. 3 at PCM C2 harness connector. (Scheme 3) If test light illuminates, repair short to voltage in circuit between PCM and fuel pump relay connector. After repairs, go to step 29. If test light does not illuminate, go to step 28.
8. Turn ignition off. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. On 3.5L, check for an open or short to ground in fuel pump relay control circuit between fuel pump relay connector in rear fuse block and terminal No. 3 at PCM C2 harness connector. (Scheme 3) On 4.0L, check for an open or short to ground in fuel pump relay control circuit between fuel pump relay connector in rear fuse block and terminal No. 70 at PCM C1 harness connector. (Scheme 3) On all models, if Dark Green/White wire is open or shorted to ground, repair wiring as necessary. After repairs, go to step 29. If Dark Green/White wire is not open or shorted to ground, go to step 22.
9. Turn ignition on. If fuel pump runs continuously, go to next step. If fuel pump does not run continuously, go to step 11.
10. Turn ignition off. Remove fuel pump relay. If fuel pump still runs continuously, go to step 23. If fuel pump does not run continuously, go to step 27.
11. Inspect fuse No. 1 (F/PMP) in rear fuse block. Rear fuse block is located underneath driver's side rear seat. If fuse is blown, go to next step. If fuse is okay, go to step 14.
12. Disconnect fuel pump harness in-line connector located near right side of fuel tank. Using a test light connected to positive battery voltage, probe Gray wire at fuel pump harness in-line connector. If test light illuminates, repair short to ground in Gray wire. After repairs, go to step 29. If test light does not illuminate, go to next step.
13. Check for damaged or shorted fuel pump wiring harness. Fuel pump can be accessed through an inspection panel in trunk. To inspect complete wiring harness, if may be necessary to lower fuel tank. Repair wiring harness as necessary and replace fuse. After repairs, go to step 29. If wiring harness is okay, go to step 20.
14. Turn ignition off. Remove fuel pump relay. Turn ignition on. Using a test light connected to ground, probe voltage supply circuit at fuel pump relay connector in rear fuse block. See WIRING DIAGRAMS article. If test light illuminates, go to next step. If test light does not illuminate, go to step 25.
15. Connect a 20-amp fused jumper wire between voltage supply circuit and fuel pump supply circuit (Gray wire) at fuel pump relay connector in rear fuse block. If fuel pump operates, go to step 21. If fuel pump does not operate, go to next step.
16. Disconnect fuel pump harness in-line connector located near right side of fuel tank. Check for an open or high resistance in Gray wire between fuel pump relay connector in rear fuse block and fuel pump harness in-line connector. Repair wiring as necessary. After repairs, go to step 29. If wiring is okay, go to next step.
17. Check for an open or high resistance is fuel pump ground circuit between fuel pump and ground connection. See WIRING DIAGRAMS article. Repair wiring as necessary. After repairs, go to step 29. If wiring is okay, go to next step.
18. Check for poor connections at fuel pump harness in-line connector located near right side of fuel tank. Repair connector as necessary. After repairs, go to step 29. If connector is okay, go to next step.
19. Check for damaged or open fuel pump wiring harness. Fuel pump can be accessed through an inspection panel in trunk. To inspect complete wiring harness, if may be necessary to lower fuel tank. Repair wiring harness as necessary. After repairs, go to step 29. If wiring harness is okay, go to step 26.
20. Reconnect all components. Install a new No. 1 (F/PMP) fuse. Using scan tool, command fuel pump on. Recheck fuse No. 1 (F/PMP) in rear fuse block. If fuse is blown, go to step 26. If fuse is okay, no problem is indicated at this time. Fault may be intermittent.
21. Check fuel pump relay connector for poor connections. Repair connector as necessary. After repairs, go to step 29. If connector is okay, go to step 27.
22. Check PCM connectors for poor connections. PCM is located in engine compartment, inside air filter housing. Repair connectors as necessary. After repairs, go to step 29. If connectors are okay, go to step 28.
23. Repair short to voltage fuel pump supply circuit between fuel pump and fuel pump relay. After repairs, go to step 29.
24. Repair open in fuel pump relay ground circuit. See WIRING DIAGRAMS article. After repairs, go to step 29.
25. Repair open in voltage supply circuit to fuel pump relay. See WIRING DIAGRAMS article. After repairs, go to step 29.
26. Check fuel pump connector for poor connections. Repair connector as necessary. If connector is okay, replace fuel pump. After repairs, go to step 29. Replace fuse No. 1 (F/PMP), if necessary.
27. Replace fuel pump relay. After repairs, go to step 29.
28. Replace PCM. Program replacement PCM. See PROGRAMMING in appropriate SELF-DIAGNOSTICS article. After repairs, go to next step.
29. Turn ignition off. Reconnect all disconnected connectors. Turn ignition on. Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Start engine. If engine starts and continues to idle, system is okay. If engine does not start or continue to idle, go to step 2.

1. If diagnostic system check has already been performed, go to next step. If diagnostic system check has not been performed, go to DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS under DIAGNOSTIC SYSTEM CHECKS in appropriate SELF-DIAGNOSTICS article.
2. Turn ignition on, with engine off. Using scan tool, command fuel pump on. Does fuel pump operate? If yes, go to next step. If no, go to «FUEL PUMP ELECTRICAL CIRCUIT DIAGNOSIS»(/buick/lesabre/viii-2000-2005/remont/testing-diagnostics/#engine-control-system-basic-diagnostic-procedures__fuel-pump-electrical-circuit-diagnosis) .
3. Turn ignition off. Turn off all accessories. Install Fuel Pressure Gauge (J-34730-1A). Place bleed hose from fuel pressure gauge into an approved gasoline container. Turn ignition on, with engine off. Using scan tool, command fuel pump on. Bleed air out of fuel pressure gauge. It may be necessary to command the fuel pump on several times in order to obtain the highest possible fuel pressure. DO NOT start engine. Observe fuel pressure gauge, with fuel pump commanded on. Is fuel pressure within 41-47 psi (2.9-3.3 kg/cm 2 ). If yes, go to next step. If no, go to step 12 .
4. Monitor fuel pressure gauge for one minute. Does fuel pressure drop more than 5 psi (0.4 kg/cm 2 )? If yes, go to step 9 . If no, go to next step.
5. Relieve fuel pressure to 10 psi (0.7 kg/cm 2 ). Monitor fuel pressure gauge for 5 minutes. Does fuel drop more than 2 psi (0.1 kg/cm 2 ). If yes, go to step 24 . If no, go to next step.
6. Turn ignition off for 15 seconds. Turn ignition on, with engine off. Monitor fuel pressure gauge. Start engine. Does fuel pressure drop to 3-10 psi (0.2-0.7 kg/cm 2 ) when engine is started? If yes, go to next step. If no, go to step 8 .
7. Operate vehicle within the conditions of the customer's concern. Monitor fuel related parameters with a scan tool. Do any of the scan tool parameters indicate a lean condition? If yes, go to step 17 . If no, see appropriate TROUBLE SHOOTING - NO CODES article.
8. Disconnect vacuum hose from fuel pressure regulator. Operate engine at idle. Monitor fuel pressure gauge. Using a hand-held vacuum pump, apply 12-14 in. Hg (40-47 kPa) to fuel pressure regulator. Does the fuel pressure drop 3-10 psi (0.2-0.7 kg/cm 2 ) when vacuum is applied? If yes, go to step 21 . If no, go to step 23 .
9. Turn ignition off. Disconnect vacuum hose from fuel pressure regulator. Turn ignition on, with engine off. Using scan tool, command fuel pump on. Inspect for fuel leak from fuel pressure regulator vacuum port. Is fuel pressure regulator leaking fuel? If yes, go to step 23 . If no, go to next step.
10. Turn ignition off. Relieve fuel pressure. Disconnect fuel feed hose and fuel return hose from fuel rail pipes. Install Fuel Pipe Shut-Off Adapters (J-37287) between the fuel hoses and fuel rail pipes. Open valves on the fuel pipe shut-off adapters. Turn ignition on, with engine off. Using scan tool, command fuel pump on. Bleed air from fuel pressure gauge. Command the fuel pump on and then off. Close fuel feed pipe shut-off valve. Monitor fuel pressure gauge for one minute. Does the fuel pressure remain constant? If yes, go to step 19 . If no, go to next step.
11. Turn ignition off. Open fuel feed pipe shut-off valve. Turn ignition on, with engine off. Command fuel pump on and then off with a scan tool. Close the fuel return pipe shut-off valve. Monitor fuel pressure gauge for one minute. Does fuel pressure remain constant? If yes, go to step 23 . If no, go to step 20 .
12. Is fuel pressure greater than 62 psi (4.4 kg/cm 2 )? If yes, go to step 14 . If no, go to next step.
13. Is fuel pressure greater than zero psi? If yes, go to step 16 . If no, go to step 17 .
14. Turn ignition off. Relieve fuel pressure. Disconnect fuel return hose from fuel rail pipe. Attach a length of flexible fuel hose to fuel rail outlet passage. Place open end of fuel hose into an approved gasoline container. Turn ignition on, with engine off. Monitor fuel pressure gauge while fuel pump is operating. Is fuel pressure within 41-47 psi (2.9-3.3 kg/cm 2 )? If yes, go to step 22 . If no, go to next step.
15. Inspect fuel return pipe and fuel rail outlet passage for restriction. Did you find and correct the condition? If yes, go to step 25 . If no, go to step 23 .
16. Turn ignition off. Relieve fuel pressure. Disconnect fuel return hose from fuel rail pipe. Install Fuel Pipe Shut-Off Adapters (J-37287) between fuel return pipe and fuel rail. Open valve in fuel pipe shut-off adapter. Turn ignition on, with engine off. Command fuel pump on with scan tool. Bleed air from fuel system. Monitor fuel pressure gauge. Slowly close the valve in fuel return pipe shut-off adapter. Command fuel pump on with scan tool. Does the fuel pressure rise to more than 47 psi (3.3 kg/cm 2 )? If yes, go to step 23 . If no, go to next step.
17. Check for restriction in fuel filter and fuel feed pipe. Did you find and correct the condition? If yes, go to step 25 . If no, go to next step.
18. Inspect the harness connectors and ground circuits of fuel pump for poor connections. Did you find and correct the condition? If yes, go to step 25 . If no, go to next step.
19. Remove fuel sender assembly. Inspect fuel pump flex hose for damage, in-tank fuel pump harness connectors for poor connections, fuel strainer for a restriction or contaminates in fuel tank. Did you find and correct the condition? If yes, go to step 25 . If no, go to step 24 .
20. Turn ignition off. Raise fuel rail with fuel lines connected. Turn ignition on, with engine off. Using scan tool, command fuel pump on. Locate and replace leaking fuel injector(s). After repairs, go to step 25 .
21. Repair vacuum source to fuel pressure regulator. After repairs, go to step 25 .
22. Locate and repair the restricted fuel return line. After repairs, go to step 25 .
23. Replace fuel pressure regulator. After repairs, go to step 25 .
24. Replace fuel pump. After repairs, go to step, go to next step.
25. Operate the system in order to verify the repair. Did you correct the condition? If yes, system is okay. If no, go to step 3 .

Diagnostic Aids

To prevent mis-diagnosis, perform diagnostic system check. See DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS under DIAGNOSTIC SYSTEM CHECKS in appropriate SELF-DIAGNOSTICS article. Unless engine enters clear flood mode at first indication of a flooding condition, a no-start condition may result. Be sure to check spark plugs for signs of fouling. Inspect for leaks in the intake air ducting between the mass air flow sensor and throttle body. If no problems are found after performing test steps, perform diagnosis for hard start condition. See appropriate TROUBLE SHOOTING - NO CODES article.

NO START - ENGINE CRANKS OKAY (3.5L - INTRIGUE)

Note. No-start/ignition system diagnosis information is not available from manufacturer. Manufacturer provides no-start/fuel pump electrical circuit diagnosis only.

Note. Before performing the following tests, check battery condition, engine cranking speed and for adequate fuel in tank.

1. If diagnostic system check has already been performed, go to next step. If diagnostic system check has not been performed, go to DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS in appropriate SELF-DIAGNOSTICS article.
2. Does scan tool display DTCs P0036, P0412, P0418, P0443, P0449, P1546, P1689 and U1040? If yes, go to «IGNITION RELAY DIAGNOSIS»(/buick/lesabre/viii-2000-2005/remont/testing-diagnostics/#engine-control-system-basic-diagnostic-procedures__ignition-relay-diagnosis) . If no, go to next step.
3. Turn ignition on, with engine off. Using scan tool, observe the DTC information. Does scan tool display DTCs P0201-P0208, P0230, P0335, P0340, P0385, P0403, P0404, P0601, P0602, P1359, P1360 and P1404? If yes, diagnose affected DTC(s). See appropriate SELF-DIAGNOSTICS article. If no, go to next step.
4. Check fuse that supplies ignition voltage to ignition coil cassettes. See WIRING DIAGRAMS article. Is fuse open? If yes, go to «IGNITION SYSTEM DIAGNOSIS»(/buick/lesabre/viii-2000-2005/remont/testing-diagnostics/#engine-control-system-basic-diagnostic-procedures) . If no, go to next step.
5. Using scan tool, command fuel pump on. Does the fuel pump turn on? If yes, go to next step. If no, go to «FUEL PUMP ELECTRICAL CIRCUIT DIAGNOSIS»(/buick/lesabre/viii-2000-2005/remont/testing-diagnostics/#engine-control-system-basic-diagnostic-procedures) .
6. Turn ignition off. Install Fuel Pressure Gauge (J-34730-1A). Turn ignition on, with engine off. Using scan tool, command fuel pump on. Is fuel pressure within 48-55 psi (3.4-3.9 kg/cm 2 ) while fuel pump is operating? If yes, go to next step. If no, go to «FUEL SYSTEM DIAGNOSIS»(/buick/lesabre/viii-2000-2005/remont/testing-diagnostics/#engine-control-system-basic-diagnostic-procedures) .
7. Turn ignition off. Disconnect an injector connector from each cylinder bank. Install an injector test light to the injector connector. Attempt to start engine. Does test light blink while engine is cranking? If yes, go to next step. If no, diagnose using DTC P0201-P0206 test procedure. See appropriate SELF-DIAGNOSTICS article.
8. Check for a collapsed air intake duct, restricted air filter element, fouled spark plugs or a restricted exhaust system. Did you find and correct the condition? If yes, go to next step. If no, problem is intermittent. See appropriate TROUBLE SHOOTING - NO CODES article.
9. Using scan tool, clear DTCs. Attempt to start engine. Does engine start and continue to operate? If yes, go to next step. If no, go to step 2 .
10. Operate engine at idle. Allow engine to reach operating temperature. With scan tool, observe DTC information. Are any DTCs displayed? If yes, diagnose affected DTC(s). See appropriate SELF-DIAGNOSTICS article. If no, go to next step.
11. Using scan tool, review the stored information, Capture Info. Does scan tool display any DTCs that you have not diagnosed? If yes, diagnose affected DTC(s). See appropriate SELF-DIAGNOSTICS article. If no, system is okay.

Ignition Relay Diagnosis

1. If diagnostic system check has already been performed, go to next step. If diagnostic system check has not been performed, go to DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS in appropriate SELF-DIAGNOSTICS article.
2. Turn ignition off. Remove underhood fuse block cover. Remove ignition relay. Using a test light connected to ground, probe the battery positive voltage circuit for the ignition relay at underhood fuse block cavity. See WIRING DIAGRAMS article. Does test light illuminate? If yes, go to next step. If no, go to step 10 .
3. Turn ignition on, with engine off. Using test light connected to ground, probe ignition 1 voltage circuit for the ignition relay at the underhood fuse block cavity. Does test light illuminate? If yes, go to next step. If no, go to step 6 .
4. Turn ignition on, with engine off. With test light connected to battery voltage, probe the coil ground circuit for the ignition relay at the underhood fuse block cavity. Does test light illuminate? If yes, go to next step. If no, go to step 7 .
5. Turn ignition off. Using a fused jumper wire, jumper ignition relay battery positive voltage circuit and ignition relay load circuit together at underhood fuse block cavity. Using a test light connected to ground, probe oxygen sensor fuse, fuel injector fuse and Trans solenoid fuse, located in underhood fuse block. Does test light illuminate, go to step 8 . If no, go to step 10 .
6. Turn ignition off. Disconnect negative battery terminal. Disconnect the underhood fuse block harness connectors. Check the ignition 1 voltage circuit of ignition relay at underhood fuse block harness connector for an open circuit or a short to ground. Did you find and correct the condition? If yes, go to step 11 . If no, go to step 10 .
7. Turn ignition off. Disconnect negative terminal. Disconnect the underhood fuse block harness connectors. Check coil ground circuit of the ignition relay at the underhood fuse block harness connector for a high resistance or for an open circuit. Did you find and correct the condition? If yes, go to step 11 . If no, go to step 10 .
8. Inspect for poor terminal contact at ignition relay connector position of the underhood fuse block. Did you find a condition? If yes, go to step 10 . If no, go to next step.
9. Replace ignition relay. After replacing relay, go to step 11 .
10. Replace underhood fuse/relay block. After replacing fuse/relay block, go to next step.
11. Clear DTCs with scan tool. Turn ignition off for 30 seconds. Start engine. Operate vehicle for 5 minutes. Does vehicle operate normally, with no Malfunction Indicator Light (MIL) illumination and no stored DTCs? If yes, system is okay. If no, diagnose affected DTC(s). See appropriate SELF-DIAGNOSTICS article.

1. If diagnostic system check has already been performed, go to next step. If diagnostic system check has not been performed, go to DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS in appropriate SELF-DIAGNOSTICS article.
2. Start engine. Select the Misfire Current counters on scan tool. Do any cylinders indicate an excessive amount of misfire? If yes, go to next step. If no, go to step 11 .
3. Is an entire bank of cylinders inoperative? If yes, go to step 16 . If no, go to next step.
4. Use scan tool to check for DTC P1351-P1366. If no IC circuit DTCs are set, inspect the IC circuit status. Are any IC circuit DTCs set or does the IC circuit status for any cylinder indicate anything other than okay? If yes, diagnose affected DTC(s). See appropriate SELF-DIAGNOSTICS article. If no, go to next step.
5. Disconnect the coil assembly from spark plugs. Check coil assembly, boots and spark plug insulators for any visible cracks, deterioration or other damage. Check for carbon tracking or other signs of arcing. Did you find a problem? If yes, go to step 20 . If no, go to next step.
6. Using Ignition System Diagnosis Harness (J-36012-A), connect the coils to the spark plugs. Disconnect the spark plug on the affected cylinder and install Spark Tester (J-26792). Crank engine and note spark tester. If engine starts, turn engine off after inspecting the spark tester. Does a spark jump the tester gap? If yes, go to next step. If no, go to step 10 .
7. Remove spark plug on affected cylinder. Does spark plug show signs of oil or coolant entering the combustion chamber? If yes, diagnose for an engine mechanical problem. If no, go to next step.
8. Inspect spark plug for any cracks, excessive wear, improper gap, burned electrodes, heavy deposits or fuel fouling. Did you find a problem? If yes, go to step 24 . If no, go to next step.
9. Install this spark plug in a different cylinder. Switch the 2 spark plugs. Reconnect coils to plugs using spark plug jumper wires. Using scan tool, select the Misfire Current counters. Start engine. Did the misfire follow the spark plug? If yes, go to step 24 . If no, diagnose for an engine mechanical problem.
10. Turn ignition off. Remove fuel pump fuse. Disconnect harness connector from the Ignition Control (IC) module. Connect a DVOM between the ignition control circuit for the affected cylinder and ground. Set DVOM to AC Hertz. Measure frequency on the ignition control circuit for the affected cylinder while cranking engine. Does frequency measure within 2-20 Hz? If yes, go to step 25 . If no, go to step 30 .
11. Select the Misfire History counters using scan tool. Do any cylinders indicate a history of misfiring? If yes, go to next step. If no, go to step 33 .
12. Disconnect the coil assembly from spark plugs. Inspect coil assembly, boots and spark plug insulators for any visible cracks, deterioration or other damage. Check for any carbon tracking or other signs of arcing. Did you find a problem? If yes, go to step 20 . If no, go to next step.
13. Does the spark plug show signs of oil or coolant entering the combustion chamber? If yes, diagnose for an engine mechanical problem. If no, go to next step.
14. Remove spark plug on affected cylinder. Inspect spark plug for any cracks, excessive wear, improper gap, burned electrodes, any heavy deposits or fuel fouling. Did you find a problem? If yes, go to step 24 . If no, go to next step.
15. Check resistance of affected spark plugs. Does resistance measure less than 15,000 ohms. If yes, diagnose for an engine mechanical problem. If no, go to step 24 .
16. Turn ignition off. Disconnect ignition control module for the affected cylinders. Turn ignition on. Using a test light connected to ground, probe the ignition feed circuit in the ignition control module harness. Does the test light illuminate? If yes, go to next step. If no, go to step 21 .
17. Connect test light between the ignition feed circuit and ground circuit in the ignition control module harness. Does the test light illuminate? If yes, go to next step. If no, go to step 22 .
18. Using a DVOM, measure resistance between the ground circuit and reference low circuit in the harness connector of the ignition control module. Does resistance measure less than or equal to 5 ohms. If yes, go to next step. If no, go to step 23 .
19. Turn ignition off. Remove fuel pump fuse (located in underhood fuse block). Disconnect ignition control module harness connector. Connect a DVOM between the IC circuit of one of the affected cylinders and ground. Set DVOM to AC Hertz. Measure the frequency while cranking engine. Repeat test on each IC circuit. Does frequency measure within 2-20 Hz. If yes, go to step 25 . If no, go to step 30 .
20. Perform any repairs as necessary. Did you complete the repairs? If yes, go to step 31 . If no, go to step 33 .
21. Repair open or high resistance in ignition 1 voltage circuit. Did you complete the repair? If yes, go to step 31 . If no, go to step 33 .
22. Repair open or high resistance in the ground circuit. Did you complete the repair? If yes, go to step 31 . If no, go to step 33 .
23. Repair open or high resistance in the low reference circuit. Did you complete the repair? If yes, go to step 31 . If no, go to step 33 .
24. Replace spark plugs as necessary. Did you complete the replacement? If yes, go to step 31 . If no, go to step 33 .
25. Turn ignition off. Remove fuel pump fuse before proceeding. Remove ignition control module from ignition coil assembly. If mating connector between the module and coils came off with the module, remove the mating connector and install the connector into the coil assembly. Reconnect ignition control module to engine harness. Connect the Ignition Module Tester (J-43298) to ignition control module. Crank engine while observing tester. Does the 3 LEDs flash on and off as engine is cranked? If yes, go to next step. If no, go to step 28 .
26. Inspect for poor connections or terminal tension between the IC module and coil assembly. Did you find and correct the condition? If yes, go to step 31 . If no, go to next step.
27. Replace the affected coil assembly. After replacing coil assembly, go to step 31 .
28. Inspect for poor connections or terminal tension at IC module. Was a problem found and corrected? If yes, go to step 31 . If no, go to next step.
29. Replace ignition control module. After replacing module, go to step 31 .
30. Replace PCM. After replacing PCM, go to next step.
31. Start engine. Select the Misfire Current counters on scan tool. Do any cylinders indicate an excessive amount of misfire? If yes, go to next step. If no, go to step 33 .
32. Is misfire indicated on the same cylinders that were just diagnosed? If yes, diagnose engine mechanical problem. If no, go to step 3 .
33. Using scan tool, clear DTCs. Operate vehicle. Does scan tool indicate that this test passed? If yes, go to next step. If no, go to step 2 .
34. Using scan tool, select the Capture Info option and Review Info option. Does scan tool display any DTCs that you have not diagnosed? If yes, diagnose affected DTC(s). See appropriate SELF-DIAGNOSTICS article. If no, system is okay.

Fuel Pump Electrical Circuit Diagnosis

1. If diagnostic system check has already been performed, go to next step. If diagnostic system check has not been performed, go to DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS in appropriate SELF-DIAGNOSTICS article.
2. Turn ignition on. Using scan tool, command fuel pump relay on and off. If fuel pump turns on and off, check for intermittent problem. See appropriate TROUBLE SHOOTING - NO CODES article. If fuel pump does not turn on and off, go to next step.
3. Using scan tool, command fuel pump relay on and off. If fuel pump relay clicks, go to step 9 . If fuel pump relay does not click, go to next step.
4. Turn ignition off. Disconnect fuel pump relay located in underhood accessory wiring junction block. Turn ignition on. Using test light connected to ground, probe fuel pump relay control circuit at relay cavity. Using scan tool, command fuel pump relay on and off. If test light turns on and off, go to next step. If test light does not turn on and off, go to step 6 .
5. Connect test light between fuel pump relay control circuit and ground circuit at relay cavities. Using scan tool, command fuel pump relay on and off. If test light turns on and off, go to step 21 . If test light does not turn on and off, go to step 24 .
6. If test light remains illuminated with each command, go to next step. If test light does not turn on at all, go to step 8 .
7. Disconnect PCM. Check fuel pump relay control circuit for short to voltage. Repair as necessary. After repairs, go to step 29 . If circuit is okay, go to step 28 .
8. Disconnect PCM. Check fuel pump relay control circuit for open or short to ground. Repair as necessary. After repairs, go to step 29 . If circuit is okay, go to step 22 .
9. Turn ignition on. If fuel pump runs continuously, go to next step. If fuel pump does not run continuously, go to step 11 .
10. Turn ignition off. Disconnect fuel pump relay located in underhood accessory wiring junction block. Turn ignition on. If fuel pump runs continuously, go to step 23 . If fuel pump does not run continuously, go to step 27 .
11. Check F/PMP fuse (15-amp) located in underhood accessory wiring junction block. If fuse is open, go to next step. If fuse is okay, go to step 14 .
12. Disconnect the fuel pump harness in-line connector located near fuel tank. Check supply voltage circuit of fuel pump for a short to ground. Replace fuel pump fuse if necessary. Did you find and correct the condition? If yes, go to step 29 . If no, go to next step.
13. Lower fuel tank, if necessary. Check or inspect fuel tank electrical harness for damage to harness, or a grounded circuit. Replace fuel pump fuse, if necessary. Did you find and correct the condition? If yes, go to step 29 . If no, go to step 20 .
14. Turn ignition off. Disconnect fuel pump relay located in underhood accessory wiring junction block. Turn ignition on. Using test light connected to ground, probe fuel pump relay battery feed circuit at fuel pump relay cavity. If test light illuminates, go to next step. If test light does not illuminate, go to step 25 .
15. Connect fused jumper wire between fuel pump relay battery feed circuit and fuel pump power feed circuit at fuel pump relay cavities. If fuel pump runs, go to step 21 . If fuel pump does not run, go to next step.
16. Disconnect fuel pump harness in-line connector located near fuel tank. Check supply voltage circuit of the fuel pump for an open or high resistance between fuel pump relay and in-line connector. Did you find and correct the condition? If yes, go to step 29 . If no, go to next step.
17. Check fuel pump ground circuit for open or high resistance. Repair as necessary. After repairs, go to step 29 . If circuit is okay, go to next step.
18. Inspect for poor connections at fuel pump in-line connector to body pass-through connector. Did you find and correct the condition? If yes, go to step 29 . If no, go to next step.
19. Lower fuel tank. Test or inspect fuel tank electrical harness for damage to harness or open circuit. Did you find and correct the condition? If yes, go to step 29 . If no, go to step 26 .
20. Connect all disconnected components. Install new fuel pump fuse. Using scan tool, command fuel pump on. If fuel pump fuse opens, go to step 26 . If fuse is okay, problem is intermittent.
21. Check for poor connections at fuel pump relay. Repair as necessary. After repairs, go to step 29 . If connections are okay, go to step 27 .
22. Check for poor connections at PCM. Repair as necessary. After repairs, go to step 29 . If connections are okay, go to step 28 .
23. Repair short to voltage in fuel pump power supply circuit. After repairs, go to step 29 .
24. Repair open in fuel pump relay ground circuit. After repairs, go to step 29 .
25. Repair fuel pump relay battery feed circuit. After repairs, go to step 29 .
26. Replace fuel pump. Replace F/PMP fuse (15-amp) if necessary. After repairs, go to step 29 .
27. Replace fuel pump relay. After repairs, go to step 29 .
28. Replace PCM. Perform PCM relearn procedure. After repairs, go to next step.
29. Operate system and verify repair. If system operation is okay, testing is complete. If system operation is not okay, go to step 2 .

1. If diagnostic system check has already been performed, go to next step. If diagnostic system check has not been performed, go to DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS in appropriate SELF-DIAGNOSTICS article.
2. Turn ignition on, with engine off. Using scan tool, command fuel pump on. Does fuel pump operate? If yes, go to next step. If no, go to «FUEL PUMP ELECTRICAL CIRCUIT DIAGNOSIS»(/buick/lesabre/viii-2000-2005/remont/testing-diagnostics/#engine-control-system-basic-diagnostic-procedures) .
3. Turn ignition and all accessories off. Install Fuel Pressure Gauge (J-34730-1A). Place fuel pressure gauge bleed hose into an approved gasoline container. Turn ignition on, with engine off. Using scan tool, command fuel pump on. Bleed air out of fuel pressure gauge. You may need to command the fuel pump on several times in order to obtain the highest possible fuel pressure. DO NOT start engine. Observe fuel pressure gauge with fuel pump commanded on. Is fuel pressure within 41-47 psi (2.9-3.3 kg/cm 2 ). If yes, go to next step. If no, go to step 12 .
4. The fuel pressure may vary slightly when fuel pump stops running. After fuel pump stops running, fuel pressure should stabilize and remain constant. Monitor fuel pressure gauge for one minute. Does fuel pressure drop more than 5 psi (0.4 kg/cm 2 )? If yes, go to step 9 . If no, go to next step.
5. Relieve fuel pressure to 10 psi (0.7 kg/cm 2 ). Monitor fuel pressure gauge for 5 minutes. Does fuel pressure drop more than 2 psi (0.1 kg/cm 2 )? If yes, go to step 24 . If no, go to step next.
6. Turn ignition off for 15 seconds. Turn ignition on, with engine off. Monitor fuel pressure gauge. Start engine. Does fuel pressure drop to 3-10 psi (0.2-0.7 kg/cm 2 ) when engine is started? If yes, go to next step. If no, go to step 8 .
7. Operate vehicle within the conditions of the customer's concern. Monitor fuel related parameters with a scan tool. Do any of the scan tool parameters indicate a lean condition? If yes, go to step 17 . If no, problem is intermittent. See appropriate TROUBLE SHOOTING - NO CODES article.
8. Disconnect vacuum hose from fuel pressure regulator. Monitor fuel pressure gauge. Operate engine at idle. Using a hand-held vacuum pump, apply 12-14 in. Hg (40 kPa) to fuel pressure regulator. Does fuel pressure drop to 3-10 psi (0.2-0.7 kg/cm 2 ) when vacuum is applied? If yes, go to step 21 . If no, go to step 23 .
9. Turn ignition off. Disconnect vacuum hose from fuel pressure regulator. Turn ignition on, with engine off. Using scan tool, command fuel pump on. Inspect for fuel leak at fuel pressure regulator vacuum port. Is fuel pressure regulator leaking fuel? If yes, go to step 23 . If no, go to next step.
10. Turn ignition off. Relieve fuel pressure. Disconnect fuel feed hose and fuel return hose from fuel rail pipes. Install Fuel Pipe Shut-Off Adapters (J-37287) between fuel hoses and fuel rail pipes. Open valves on fuel pipe shut-off adapters. Turn ignition on, with engine off. Command fuel pump on with scan tool. Bleed air from fuel pressure gauge. Command fuel pump on and then off with scan tool. Close fuel feed pipe shut-off valve. Monitor fuel pressure gauge for one minute. Does fuel pressure remain constant? If yes, go to step 19 . If no, go to next step.
11. Turn ignition off. Open fuel feed pipe shut-off valve. Turn ignition on, with engine off. Command fuel pump on and then off with scan tool. Close fuel return pipe shut-off valve. Monitor fuel pressure gauge for one minute. Does fuel pressure remain constant? If yes, go to step 23 . If no, go to step 20 .
12. Is fuel pressure greater than 62 psi (4.4 kg/cm 2 )? If yes, go to step 14 . If no, go to next step.
13. Is fuel pressure greater than zero psi? If yes, go to step 16 . If no, go to step 17 .
14. Turn ignition off. Relieve fuel pressure. Disconnect fuel return hose from fuel rail pipe. Attach a length of flexible fuel hose to fuel rail outlet passage. Place open end of fuel hose into an approved gasoline container. Turn ignition on, with engine off. Monitor fuel pressure gauge while fuel pump is operating. Is fuel pressure within 41-47 psi (2.9-3.3 kg/cm 2 )? If yes, go to step 22 . If no, go to next step.
15. Inspect fuel return pipe and fuel rail outlet passage for a restriction. Did you find and correct the condition? If yes, go to step 25 . If no, go to step 23 .
16. Turn ignition off. Relieve fuel pressure. Disconnect fuel return hose from fuel rail pipe. Install Fuel Pipe Shut-off Adapters (J-37287) between fuel return pipe and fuel rail. Open valve in fuel pipe shut-off adapter. Turn ignition on, with engine off. Command fuel pump on with scan tool. Bleed air from fuel system. Monitor fuel pressure gauge. DO NOT allow fuel pressure to exceed 75 psi (5.3 kg/cm 2 ). Excessive pressure may damage fuel system. Slowly close valve in fuel return pipe shut-off adapter. Command fuel pump on with scan tool. Does fuel pressure increase to more than 47 psi (3.3 kg/cm 2 )? If yes, go to step 23 . If no, go to next step.
17. Check for a restricted fuel filter or fuel feed pipe. Did you find and correct the condition? If yes, go to step 25 . If no, go to next step.
18. Inspect fuel pump harness connectors and ground circuits for poor connections. Did you find and correct the condition? If yes, go to step 25 . If no, go to next step.
19. Remove fuel sender assembly. Check fuel pump flex hose for damage, in-tank fuel pump harness connectors for poor connections, fuel strainer for a restriction or contaminates in fuel tank. Did you find and correct the condition? If yes, go to step 25 . If no, go to step 24 .
20. Turn ignition off. Raise fuel rail with fuel lines connected. Turn ignition on, with engine off. Command fuel pump on with scan tool. Locate and replace leaking fuel injector. After repairs, go to step 25 .
21. Repair vacuum source to fuel pressure regulator. After repairs, go to step 25 .
22. Locate and repair restricted fuel return line. After repairs, go to step 25 .
23. Replace fuel pressure regulator. After replacing fuel pressure regulator, go to step 25 .
24. Replace fuel pump. After replacing fuel pump, go to next step.
25. Operate system in order to verify the repair. Did you correct the condition? If yes, system is okay. If no, go to step 3 .

NO START - ENGINE CRANKS OKAY (3.8L)

Note. Before performing the following tests, check battery condition, engine cranking speed and for adequate fuel in tank. After fault has been isolated and repairs have been completed, perform diagnostic system check. See DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS in appropriate SELF-DIAGNOSTICS article.

General Inspection (VIN K - Camaro & Firebird)

1. If diagnostic system check has already been performed, go to next step. If diagnostic system check has not been performed, go to DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS in appropriate SELF-DIAGNOSTICS article.
2. Turn ignition on, with engine off. Observe DTC information with scan tool. Is DTC P0230, P0336, P0341, P0601, P0602, P0604, P0606, P1626 or P1629 set? If yes, diagnose affected DTC(s). See appropriate SELF-DIAGNOSTICS article. If no, go to next step.
3. Turn ignition on, with engine off. Using a test light connected to ground, test both sides of ENG, CTRL and Fuel injectors fuses. Fuses are located in underhood fuse block. Does test light illuminate on at least one side of each fuse? If yes, go to next step. If no, go to «IGNITION RELAY DIAGNOSIS»(/buick/lesabre/viii-2000-2005/remont/testing-diagnostics/#engine-control-system-basic-diagnostic-procedures__ignition-relay-diagnosis-vin-k) .
4. Using scan tool, monitor engine RPM parameter while engine is cranking. Does engine RPM parameter display cranking RPM? If yes, go to next step. If no, go to «IGNITION SYSTEM DIAGNOSIS (ALL MODELS)»(/buick/lesabre/viii-2000-2005/remont/testing-diagnostics/#engine-control-system-basic-diagnostic-procedures__ignition-system-diagnosis-all-models) .
5. Command fuel pump relay on with scan tool. Does fuel pump run? If yes, go to next step. If no, go to «FUEL PUMP ELECTRICAL CIRCUIT (EXCEPT VIN K - GRAND PRIX)»(/buick/lesabre/viii-2000-2005/remont/testing-diagnostics/#engine-control-system-basic-diagnostic-procedures__fuel-pump-electrical-circuit-except-vin) .
6. Turn ignition off. Install Fuel Pressure Gauge (J-34730-1A). Turn ignition on, with engine off. Command fuel pump relay on with scan tool. Is fuel pressure within 48-55 psi (3.4-3.9 kg/cm 2 ) while fuel pump is operating? If yes, go to next step. If no, go to «FUEL SYSTEM DIAGNOSIS (ALL MODELS)»(/buick/lesabre/viii-2000-2005/remont/testing-diagnostics/#engine-control-system-basic-diagnostic-procedures__fuel-system-diagnosis-all-models) .
7. Turn ignition off. Disconnect a fuel injector connector. Install Fuel Injector Test Light (J-34730-405) to the fuel injector connector. Attempt to start engine. Does test light blink while the engine is cranking? If yes, go to step 9 . If no, go to next step.
8. Remove Fuel Injector Test Light (J-34730-405) from fuel injector connector. Turn ignition on, with engine off. Probe ignition 1 voltage supply circuit of the fuel injector with a test light connected to ground. Does test light illuminate? If yes, diagnose using DTC P0341 test procedure. See appropriate SELF-DIAGNOSTICS article. If no, go to «FUEL INJECTOR CIRCUIT (VIN K - CAMARO, FIREBIRD, IMPALA & MONTE CARLO)»(/buick/lesabre/viii-2000-2005/remont/testing-diagnostics/#engine-control-system-basic-diagnostic-procedures__fuel-injector-circuit-vin-k) .
9. Turn ignition off. Disconnect a spark plug wire. Install Spark Tester (J-26792) to spark plug wire. Start engine. Does spark tester spark? If yes, go to next step. If no, go to «IGNITION SYSTEM DIAGNOSIS (ALL MODELS)»(/buick/lesabre/viii-2000-2005/remont/testing-diagnostics/#engine-control-system-basic-diagnostic-procedures__ignition-system-diagnosis-all-models) .
10. Check for collapsed air intake duct, restricted air filter element, fouled spark plugs, engine mechanical problem or restricted exhaust system. Check for faulty Engine Coolant Temperature (ECT) sensor, Manifold Absolute Pressure (MAP) sensor or a stuck Throttle Position (TP) sensor. Repair or replace as necessary. After repairs, go to next step.
11. Using scan tool, clear DTCs. Start engine. Does engine start and continue to operate? If yes, go to next step. If no, go to step 2 .
12. Operate engine at idle. Allow engine to reach operating temperature. Observe DTC information with scan tool. Are any DTCs displayed? If yes, diagnose affected DTC(s). If no, go to next step.
13. Observe the Capture Info with a scan tool. Are there any DTCs that have not been diagnosed? If yes, diagnose affected DTC(s). See appropriate SELF-DIAGNOSTICS article. If no, system is okay.

General Inspection (VIN K & 1 - Grand Prix)

1. If diagnostic system check has already been performed, go to next step. If diagnostic system check has not been performed, go to DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS in appropriate SELF-DIAGNOSTICS article.
2. Turn ignition on, with engine off. Observe DTC information with scan tool. Is DTC P0230, P0336, P0341, P0601 or P0602 set? If yes, diagnose affected DTC(s). See appropriate SELF-DIAGNOSTICS article. If no, go to next step.
3. Using scan tool, monitor engine RPM parameter while engine is cranking. Does engine RPM parameter display cranking RPM? If yes, go to next step. If no, go to «IGNITION SYSTEM DIAGNOSIS (ALL MODELS)»(/buick/lesabre/viii-2000-2005/remont/testing-diagnostics/#engine-control-system-basic-diagnostic-procedures__ignition-system-diagnosis-all-models) .
4. Turn ignition on, with engine off. Check for open in ECM, ECM Sense, fuel pump, Inj and Elek Ign fuses. Did you find an open fuse? If yes, go to step 11 . If no, go to next step.
5. Using test light connected to ground, probe both sides of the INJ fuse and Elek fuse. Does test light illuminate on at least one side of each fuse? If yes, go to next step. If no, go to «IGNITION RELAY DIAGNOSIS (VIN K & 1 - GRAND PRIX)»(/buick/lesabre/viii-2000-2005/remont/testing-diagnostics/#engine-control-system-basic-diagnostic-procedures__ignition-relay-diagnosis-vin-k) .
6. Using scan tool, command fuel pump relay on. Does fuel pump run? If yes, go to next step. If no, go to «FUEL PUMP ELECTRICAL CIRCUIT (VIN K - GRAND PRIX)»(/buick/lesabre/viii-2000-2005/remont/testing-diagnostics/#engine-control-system-basic-diagnostic-procedures__fuel-pump-electrical-circuit-vin-k) or «FUEL PUMP ELECTRICAL CIRCUIT (EXCEPT VIN K - GRAND PRIX)»(/buick/lesabre/viii-2000-2005/remont/testing-diagnostics/#engine-control-system-basic-diagnostic-procedures__fuel-pump-electrical-circuit-except-vin) .
7. Turn ignition off. Install Fuel Pressure Gauge (J-34730-1A). Turn ignition on, with engine off. Using scan tool, command fuel pump relay on. Is fuel pressure within 53-59 psi (3.7-4.1 kg/cm 2 ) while fuel pump is operating? If yes, go to next step. If no, go to «FUEL SYSTEM DIAGNOSIS (ALL MODELS)»(/buick/lesabre/viii-2000-2005/remont/testing-diagnostics/#engine-control-system-basic-diagnostic-procedures__fuel-system-diagnosis-all-models) .
8. Turn ignition off. Disconnect a fuel injector connector. Install Fuel Injector Test Light (J-34730-405) to fuel injector connector. Attempt to start engine. Does test light blink while engine is cranking? If yes, go to next step. If no, go to «FUEL INJECTOR CIRCUIT DIAGNOSIS (VIN K & 1 - BONNEVILLE, GRAND PRIX, LESABRE & PARK AVENUE)»(/buick/lesabre/viii-2000-2005/remont/testing-diagnostics/#engine-control-system-basic-diagnostic-procedures__fuel-injector-circuit-diagnosis-vin-k) .
9. Turn ignition off. Disconnect a spark plug wire. Install a Spark Tester (J-26792) to spark plug wire. Attempt to start engine. Does spark tester spark? If yes, go to next step. If no, go to «IGNITION SYSTEM DIAGNOSIS (ALL MODELS)»(/buick/lesabre/viii-2000-2005/remont/testing-diagnostics/#engine-control-system-basic-diagnostic-procedures__ignition-system-diagnosis-all-models) .
10. Check for collapsed air intake duct, restricted air filter element, fouled spark plugs, an engine mechanical condition or a restricted exhaust system. Check for faulty ECT and MAP sensor. Check for a stuck TP sensor. Repair as necessary. After repairs, go to step 12 .
11. Isolate the excessive current draw in circuit or component supplied by open fuse. See WIRING DIAGRAMS article. Repair short to ground in circuit or replace component, as necessary. Replace open fuse. After repairs, go to step 12 .
12. Clear DTCs with scan tool. Attempt to start engine. Does engine start and continue to operate? If yes, go to next step. If no, go to step 2 .
13. Operate engine at idle. Allow engine to reach operating temperature. Observe DTC information on scan tool. Are any DTCs displayed? If yes, diagnose affected DTC(s). See appropriate SELF-DIAGNOSTICS article. If no, system is okay.

General Inspection (VIN K - Impala & Monte Carlo)

1. If diagnostic system check has already been performed, go to next step. If diagnostic system check has not been performed, go to DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS in appropriate SELF-DIAGNOSTICS article.
2. Turn ignition on, with engine off. Using scan tool, observe the DTC information. Is DTC P0230, P0336, P0341, P0601 or P0602 set? If yes, diagnose affected DTC(s). See appropriate SELF-DIAGNOSTICS article. If no, go to next step.
3. Turn ignition on, with engine off. Using a test light connected to ground, test both sides of each of the fuel injectors, ABS/PCM, fuel pump relay fuse and DFI module fuses. Does test light illuminate on both sides of each fuse? If yes, go to step 5 . If no, go to next step.
4. Visually inspect fuses where test light did not illuminate on both sides. Is any fuse open? If yes, go to step 14 . If no, go to «IGNITION RELAY DIAGNOSIS (VIN K - CAMARO, FIREBIRD, IMPALA & MONTE CARLO)»(/buick/lesabre/viii-2000-2005/remont/testing-diagnostics/#engine-control-system-basic-diagnostic-procedures__ignition-relay-diagnosis-vin-k) .
5. Turn ignition on, with engine off. Observe MIL. Is MIL illuminated? If yes, go to next step. If no, go to step 13 .
6. Using scan tool, monitor the engine RPM parameter while engine is cranking. Attempt to start engine. Does the engine RPM parameter display cranking RPM? If yes, go to next step. If no, go to «IGNITION SYSTEM DIAGNOSIS (ALL MODELS)»(/buick/lesabre/viii-2000-2005/remont/testing-diagnostics/#engine-control-system-basic-diagnostic-procedures__ignition-system-diagnosis-all-models) .
7. Command fuel pump relay on with scan tool. Does fuel pump run? If yes, go to next step. If no, go to «FUEL PUMP ELECTRICAL CIRCUIT (EXCEPT VIN K - GRAND PRIX)»(/buick/lesabre/viii-2000-2005/remont/testing-diagnostics/#engine-control-system-basic-diagnostic-procedures__fuel-pump-electrical-circuit-except-vin) .
8. Turn ignition off. Install Fuel Pressure Gauge (J-34730-1A). Turn ignition on, with engine off. Command fuel pump relay on with scan tool. Is fuel pressure within 53-59 psi (3.7-4.1 kg/cm 2 ) while fuel pump is operating? If yes, go to next step. If no, go to «FUEL SYSTEM DIAGNOSIS (ALL MODELS)»(/buick/lesabre/viii-2000-2005/remont/testing-diagnostics/#engine-control-system-basic-diagnostic-procedures__fuel-system-diagnosis-all-models) .
9. Turn ignition off. Disconnect a fuel injector connector. Install a Fuel Injector Test Light (J-34730-405) to fuel injector connector. Attempt to start engine. Does test light blink while engine is cranking? If yes, go to step 11 . If no, go to next step.
10. Remove injector test light from fuel injector connector. Turn ignition on, with engine off. Using a test light connected to ground, probe the ignition 1 voltage supply circuit of the fuel injector. See WIRING DIAGRAMS article. Does test light illuminate? If yes, diagnose using DTC P0341 test. See appropriate SELF-DIAGNOSTICS article. If no, go to «FUEL INJECTOR CIRCUIT (VIN K - CAMARO, FIREBIRD, IMPALA & MONTE CARLO)»(/buick/lesabre/viii-2000-2005/remont/testing-diagnostics/#engine-control-system-basic-diagnostic-procedures__fuel-injector-circuit-vin-k) .
11. Turn ignition off. Disconnect a spark plug wire. Install Spark Tester (J-26792) to spark plug wire. Attempt to start engine. Does spark tester spark? If yes, go to next step. If no, go to «IGNITION SYSTEM DIAGNOSIS (ALL MODELS)»(/buick/lesabre/viii-2000-2005/remont/testing-diagnostics/#engine-control-system-basic-diagnostic-procedures__ignition-system-diagnosis-all-models) .
12. Check for collapsed air intake duct, restricted air filter element, fouled spark plugs, engine mechanical problem or restricted exhaust system. Check for faulty Engine Coolant Temperature (ECT) sensor, Manifold Absolute Pressure (MAP) sensor or a stuck Throttle Position (TP) sensor. Repair or replace as necessary. After repairs, go to step 17 .
13. Check the ignition 1 voltage circuit between the ABS/PCM fuse (located in passenger compartment fuse block) and PCM for an open circuit. Did you find and correct the condition? If yes, go to step 17 . If no, go to step 15 .
14. Isolate the excessive current draw in the circuit or component supplied by the open fuse. Repair short to ground in circuit or replace component as necessary. Replace open fuse. After repairs, go to step 17 .
15. Inspect for poor connections at PCM. Repair as necessary. Did you find and correct the condition? If yes, go to step 17 . If no, go to next step.
16. Replace PCM. After replacing PCM, go to next step.
17. Clear DTCs with scan tool. Attempt to start engine. Does engine start and continue to operate? If yes, go to next step. If no, go to step 2 .
18. Allow engine to idle until normal operating temperature is reached. Observe the DTC Information on scan tool. Are any DTCs displayed? If yes, diagnose affected DTC(s). See appropriate SELF-DIAGNOSTICS article. If no, system is okay.

General Inspection (VIN K - Park Avenue)

1. If diagnostic system check has already been performed, go to next step. If diagnostic system check has not been performed, go to DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS in appropriate SELF-DIAGNOSTICS article.
2. Turn ignition on, with engine off. Using scan tool, observe the DTC information. Is DTC P0230, P0336, P0341, P0601 or P0602 set? If yes, diagnose affected DTC(s). See appropriate SELF-DIAGNOSTICS article. If no, go to next step.
3. Monitor engine RPM parameter on scan tool, while engine is cranking. Does the engine RPM parameter display cranking RPM? If yes, go to next step. If no, go to «IGNITION SYSTEM DIAGNOSIS (ALL MODELS)»(/buick/lesabre/viii-2000-2005/remont/testing-diagnostics/#engine-control-system-basic-diagnostic-procedures__ignition-system-diagnosis-all-models) .
4. Using scan tool, command fuel pump relay on. Does fuel pump run? If yes, go to next step. If no, go to «FUEL PUMP ELECTRICAL CIRCUIT (EXCEPT VIN K - GRAND PRIX)»(/buick/lesabre/viii-2000-2005/remont/testing-diagnostics/#engine-control-system-basic-diagnostic-procedures__fuel-pump-electrical-circuit-except-vin) .
5. Turn ignition off. Install Fuel Pressure Gauge (J-34730-1A). Turn ignition on, with engine off. Using scan tool, command the fuel pump relay on. Is fuel pressure within 53-59 psi (3.7-4.1 kg/cm 2 ) while fuel pump is operating? If yes, go to next step. If no, go to «FUEL SYSTEM DIAGNOSIS (ALL MODELS)»(/buick/lesabre/viii-2000-2005/remont/testing-diagnostics/#engine-control-system-basic-diagnostic-procedures__fuel-system-diagnosis-all-models) .
6. Turn ignition off. Disconnect a fuel injector connector. Install Fuel Injector Test Light (J-34730-405) to the injector connector. Attempt to start engine. Does test light blink while engine is cranking? If yes, go to next step. If no, go to «FUEL INJECTOR CIRCUIT DIAGNOSIS (VIN K & 1 - BONNEVILLE, GRAND PRIX, LESABRE & PARK AVENUE)»(/buick/lesabre/viii-2000-2005/remont/testing-diagnostics/#engine-control-system-basic-diagnostic-procedures__fuel-injector-circuit-diagnosis-vin-k) .
7. Turn ignition off. Disconnect a spark plug wire. Install Spark Tester (J-26792) to spark plug wire. Attempt to start engine. Does spark tester spark? If yes, go to next step. If no, go to «IGNITION SYSTEM DIAGNOSIS (ALL MODELS)»(/buick/lesabre/viii-2000-2005/remont/testing-diagnostics/#engine-control-system-basic-diagnostic-procedures__ignition-system-diagnosis-all-models) .
8. Check for collapsed air intake duct, restricted air filter element, fouled spark plugs, engine mechanical problem or restricted exhaust system. Check for faulty Engine Coolant Temperature (ECT) sensor, Manifold Absolute Pressure (MAP) sensor or a stuck Throttle Position (TP) sensor. Repair or replace as necessary. After repairs, go to next step.
9. Clear DTCs with a scan tool. Attempt to start engine. Does engine start and continue to operate? If yes, go to next step. If no, go to step 2 .
10. Operate engine at idle. Allow engine to reach operating temperature. Observe DTC information on scan tool. Are any DTCs displayed? If yes, diagnose affected DTC(s). See appropriate SELF-DIAGNOSTICS article. If no, system is okay.

General Inspection (VIN K - LeSabre; VIN 1 - Bonneville & Park Avenue)

1. If diagnostic system check has already been performed, go to next step. If diagnostic system check has not been performed, go to DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS in appropriate SELF-DIAGNOSTICS article.
2. Turn ignition on, with engine off. Using scan tool, observe DTC information. Does scan tool display DTC P0230, P0336, P0601 or P0602? If yes, diagnose affected DTC(s). See appropriate SELF-DIAGNOSTICS article. If no, go to next step.
3. Attempt to start engine. Using scan tool, monitor the engine RPM parameter while engine is cranking. Does engine RPM parameter display cranking RPM? If yes, go to next step. If no, go to «IGNITION SYSTEM DIAGNOSIS (ALL MODELS)»(/buick/lesabre/viii-2000-2005/remont/testing-diagnostics/#engine-control-system-basic-diagnostic-procedures__ignition-system-diagnosis-all-models) .
4. Using scan tool, command the fuel pump on. Does fuel pump turn on? If yes, go to next step. If no, go to «FUEL PUMP ELECTRICAL CIRCUIT (EXCEPT VIN K - GRAND PRIX)»(/buick/lesabre/viii-2000-2005/remont/testing-diagnostics/#engine-control-system-basic-diagnostic-procedures__fuel-pump-electrical-circuit-except-vin) .
5. Turn ignition off. Install Fuel Pressure Gauge (J-34730-1A). Turn ignition on, with engine off. With scan tool, command the fuel pump on. Is fuel pressure within 48-54 psi (3.4-3.8 kg/cm 2 ) while fuel pump is operating? If yes, go to next step. If no, go to «FUEL SYSTEM DIAGNOSIS (ALL MODELS)»(/buick/lesabre/viii-2000-2005/remont/testing-diagnostics/#engine-control-system-basic-diagnostic-procedures__fuel-system-diagnosis-all-models) .
6. Turn ignition off. Disconnect an injector connector. Install Injector Test Light (J-34730-405) to injector connector. Attempt to start engine. Does test light blink while engine is cranking? If yes, go to next step. If no, go to «FUEL INJECTOR CIRCUIT DIAGNOSIS (VIN K & 1 - BONNEVILLE, GRAND PRIX, LESABRE & PARK AVENUE)»(/buick/lesabre/viii-2000-2005/remont/testing-diagnostics/#engine-control-system-basic-diagnostic-procedures__fuel-injector-circuit-diagnosis-vin-k) .
7. Turn ignition off. Disconnect a spark plug wire. Install Spark Tester (J-26792) to spark plug wire. Attempt to start engine. Does spark tester spark? If yes, go to next step. If no, go to «IGNITION SYSTEM DIAGNOSIS (ALL MODELS)»(/buick/lesabre/viii-2000-2005/remont/testing-diagnostics/#engine-control-system-basic-diagnostic-procedures__ignition-system-diagnosis-all-models) .
8. Check for collapsed air intake duct, restricted air filter element, fouled spark plugs, an engine mechanical condition, restricted exhaust system or ECT sensor is NOT close to actual engine temperature. Compare Manifold Absolute Pressure/Barometric Pressure (MAP/BARO) sensor parameters to another vehicle. The parameters should be close in value. Check Throttle Position (TP) sensor for being stuck in range. Did you find and correct the condition? If yes, go to next step. If no, problem is intermittent. See appropriate TROUBLE SHOOTING - NO CODES article.
9. Using scan tool, clear DTCs. Attempt to start engine. Does engine start and continue to operate? If yes, go to next step. If no, go to step 2 .
10. Operate engine at idle. Allow engine to reach operating temperature. With scan tool, observe DTC information. Are any DTCs displayed? If yes, diagnose affected DTC(s). See appropriate SELF-DIAGNOSTICS article. If no, go to next step.
11. With scan tool review the stored information, Capture Info. Does scan tool display any DTCs that you have not diagnosed? If yes, diagnose affected DTC(s). See appropriate SELF-DIAGNOSTICS article. If no, system is okay.

General Inspection (VIN K & 1 - Regal)

1. If diagnostic system check has already been performed, go to next step. If diagnostic system check has not been performed, go to DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS in appropriate SELF-DIAGNOSTICS article.
2. Turn ignition on, with engine off. Using scan tool, observe the DTC information. Does scan tool display DTCs P0230, P0336, P0601 or P0602? If yes, diagnose affected DTC(s). See appropriate SELF-DIAGNOSTICS article. If no, go to next step.
3. Attempt to start engine. Using scan tool, monitor engine RPM parameter while engine is cranking. Does engine RPM parameter display cranking RPM? If yes, go to next step. If no, go to «IGNITION SYSTEM DIAGNOSIS (ALL MODELS)»(/buick/lesabre/viii-2000-2005/remont/testing-diagnostics/#engine-control-system-basic-diagnostic-procedures__ignition-system-diagnosis-all-models) .
4. Turn ignition on, with engine off. Using a test light connected to ground, probe both sides of the PCM, fuel pump, fuel injectors and ignition module fuses. Does test light illuminate on both sides of all the fuses? If yes, go to next step. If no, go to «IGNITION RELAY DIAGNOSIS (VIN K & 1 - REGAL)»(/buick/lesabre/viii-2000-2005/remont/testing-diagnostics/#engine-control-system-basic-diagnostic-procedures__ignition-relay-diagnosis-vin-k) .
5. Using scan tool, command fuel pump on. Does fuel pump turn on? If yes, go to next step. If no, go to «FUEL PUMP ELECTRICAL CIRCUIT (EXCEPT VIN K - GRAND PRIX)»(/buick/lesabre/viii-2000-2005/remont/testing-diagnostics/#engine-control-system-basic-diagnostic-procedures__fuel-pump-electrical-circuit-except-vin) .
6. Turn ignition off. Install Fuel Pressure Gauge (J-34730-1A). Turn ignition on, with engine off. Using scan tool, command the fuel pump on. Is fuel pressure within 53-59 psi (3.7-4.1 kg/cm 2 ) for VIN K or 48-54 psi (3.4-3.8 kg/cm 2 ) for VIN 1 while the fuel pump is operating? If yes, go to next step. If no, go to «FUEL SYSTEM DIAGNOSIS (ALL MODELS)»(/buick/lesabre/viii-2000-2005/remont/testing-diagnostics/#engine-control-system-basic-diagnostic-procedures__fuel-system-diagnosis-all-models) .
7. Turn ignition off. Disconnect an injector connector. Install Injector Test Light (J-34730-405) or TBI Harness Test Light (J-34730-2C) to injector connector. Attempt to start engine. Does test light blink while engine is cranking? If yes, go to next step. If no, go to «FUEL INJECTOR CIRCUIT DIAGNOSIS (VIN K & 1 - REGAL)»(/buick/lesabre/viii-2000-2005/remont/testing-diagnostics/#engine-control-system-basic-diagnostic-procedures__fuel-injector-circuit-diagnosis-vin-k) .
8. Turn ignition off. Disconnect a spark plug wire. Install Spark Tester (J-26792) to the spark plug wire. Attempt to start engine. Does spark tester spark? If yes, go to next step. If no, go to «IGNITION SYSTEM DIAGNOSIS (ALL MODELS)»(/buick/lesabre/viii-2000-2005/remont/testing-diagnostics/#engine-control-system-basic-diagnostic-procedures__ignition-system-diagnosis-all-models) .
9. Check for collapsed air intake duct, restricted air filter element, fouled spark plugs, an engine mechanical condition, restricted exhaust system or ECT sensor NOT close to actual engine temperature. Compare Manifold Absolute Pressure/Barometric Pressure (MAP/BARO) parameters to another vehicle. Parameters should be close in value. Check Throttle Position (TP) sensor for being stuck in range. Did you find and correct the condition? If yes, go to next step. If no, problem is intermittent. See appropriate TROUBLE SHOOTING - NO CODES article.
10. Use scan tool in order to clear DTCs. Attempt to start engine. Does engine start and continue to operate? If yes, go to next step. If no, go to step 2 .
11. Operate engine at idle. Allow engine to reach operating temperature. Use scan tool in order to observe the DTC information. Are any DTCs displayed? If yes, diagnose affected DTC(s). See appropriate SELF-DIAGNOSTICS article. If no, go to next step.
12. Using scan tool, observe the stored information, Capture Info. Does scan tool display any DTCs that you have not diagnosed? If yes, diagnose affected DTC(s). See appropriate SELF-DIAGNOSTICS article. If no, system is okay.

Ignition Relay Diagnosis (VIN K - Camaro, Firebird, Impala & Monte Carlo)

1. If diagnostic system check has already been performed, go to next step. If diagnostic system check has not been performed, go to DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS in appropriate SELF-DIAGNOSTICS article.
2. Turn ignition off. Remove underhood fuse/relay block. Remove ignition relay. Using a test light connected to ground, probe the battery positive voltage circuit of the ignition relay at the underhood fuse/relay block cavity. See WIRING DIAGRAMS article. Does the test light illuminate? If yes, go to next step. If no, go to step 6 .
3. Turn ignition on, with engine off. Using test light connected to ground, probe the ignition 1 voltage circuit of the ignition relay at the underhood fuse/relay block. Does test light illuminate? If yes, go to next step. If no, go to step 7 .
4. Turn ignition on, with engine off. Using test light connected to battery voltage, probe the coil ground circuit of the ignition relay at underhood fuse/relay block. Does the test light illuminate? If yes, go to next step. If no, go to step 8 .
5. Turn ignition off. Using a fused jumper wire, jumper the ignition relay battery positive voltage circuit and ignition relay load circuit together at the underhood fuse/relay block. Using a test light connected to ground, probe the INJ1, INJ2 and ENG CTRL fuses. Does the test light illuminate? If yes, go to step 10 . If no, go to step 9 .
6. Repair open or short to ground in battery positive voltage circuit of the ignition relay. After repairs, go to step 12 .
7. Repair open or short to ground in the ignition 1 voltage circuit of the ignition relay. After repairs, go to step 12 .
8. Repair high resistance or open in ground circuit of the ignition relay. After repairs, go to step 12 .
9. Repair high resistance or an open in load circuit of the ignition relay. After repairs, go to step 12 .
10. Inspect for poor terminal contact at ignition relay position of the underhood fuse/relay block. Did you find and correct the condition? If yes, go to step 12 . If no, go to next step.
11. Replace ignition relay. After replacing relay, go to next step.
12. Remove all test equipment. Reconnect any disconnected components, fuses, etc. Turn ignition off for 30 seconds. Start and operate vehicle. Observe the MIL, vehicle performance and driveability. Does vehicle operate normally, with no MIL illumination and no stored DTCs? If yes, system is okay. If no, diagnose affected DTC(s). See appropriate SELF-DIAGNOSTICS article.

Ignition Relay Diagnosis (VIN K & 1 - Grand Prix)

1. If diagnostic system check has already been performed, go to next step. If diagnostic system check has not been performed, go to DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS in appropriate SELF-DIAGNOSTICS article.
2. Turn ignition off. Remove underhood fuse/relay block cover. Remove ignition relay. Using a test light connected to ground, probe the ignition relay battery positive voltage circuit at the underhood fuse/relay block cavity. See WIRING DIAGRAMS article. Does the test light illuminate? If yes, go to next step. If no, go to step 8 .
3. Turn ignition on, with engine off. Using test light connected to ground, probe the ignition relay ignition run/crank voltage circuit at the underhood fuse/relay block. Does test light illuminate? If yes, go to next step. If no, go to step 9 .
4. Turn ignition on, with engine off. Using test light connected to battery voltage, probe ignition main relay ground connector terminal in fuse/relay block. Does the test light illuminate? If yes, go to next step. If no, go to step 10 .
5. Turn ignition off. Using a fused jumper wire, jumper the ignition relay battery positive voltage circuit and IGN relay load circuit. See WIRING DIAGRAMS article. Using test light connected to ground, probe INJ, DFI and TCC fuses. Fuses are located in underhood fuse/relay block. If test light illuminates, go to next step. If test light does not illuminate, go to step 10 .
6. Check for poor terminal contact at ignition relay in the underhood fuse/relay block. Did you find and correct the condition? If yes, go to step 11 . If no, go to next step.
7. Replace ignition relay. After replacing relay, go to step 11 .
8. Repair open or short to ground in battery positive voltage supply to ignition relay. After repairs, go to step 11 .
9. Repair ignition positive voltage circuit to ignition relay. After repairs, go to 11 .
10. Replace the underhood fuse/relay block. After replacing fuse/relay block, go to 11 .
11. Remove all test equipment. Reconnect any disconnected components, fuses, etc. Turn ignition off for 30 seconds. Start engine and operate vehicle. Observe MIL, vehicle performance and driveability. Does vehicle operate normally, with no MIL illumination and no stored DTCs? If yes, system is okay. If no, diagnose affected DTC(s). See appropriate SELF-DIAGNOSTICS article.

Ignition Relay Diagnosis (VIN K & 1 - Regal)

1. If diagnostic system check has already been performed, go to next step. If diagnostic system check has not been performed, go to DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS in appropriate SELF-DIAGNOSTICS article.
2. Turn ignition off. Remove the underhood fuse/relay block cover. Remove the IGN relay. Using a test light connected to ground, probe the IGN relay battery positive voltage circuit at the underhood fuse/relay block cavity. See WIRING DIAGRAMS article. Does the test light illuminate? If yes, go to next step. If no, go to step 8 .
3. Turn ignition on, with engine off. Using test light, probe the IGN relay ignition run/crank voltage circuit at the underhood fuse/relay block cavity. Does test light illuminate? If yes, go to next step. If no, go to step 9 .
4. Turn ignition on, with engine off. Using test light connected to battery voltage, probe the ignition main relay ground connector terminal. Does the test light illuminate? If yes, go to next step. If no, go to step 10 .
5. Turn ignition off. Using a fused jumper wire, jumper the IGN relay battery positive voltage circuit and the IGN relay load circuit together. See WIRING DIAGRAMS article. Using test light connected to ground, probe the F/INJR, ENG EMIS and OXY SEN fuses. Does the test light illuminate? If yes, go to next step. If no, go to step 10 .
6. Inspect for poor terminal contact at the IGN relay underhood fuse/relay block connector. Did you find and correct the condition? If yes, go to step 11 . If no, go to next step.
7. Replace the IGN relay. After replacing relay, go to step 11 .
8. Repair open or short to ground in the battery positive voltage supply to IGN relay. After repairs, go to step 11 .
9. Repair ignition positive voltage circuit to IGN relay. After repairs, go to step 11 .
10. Replace the underhood fuse/relay block. After replacing fuse/relay block, go to next step.
11. Remove all test equipment. Reconnect any disconnected components, fuses, etc. Turn ignition off for 30 seconds. Start 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. If no, diagnose affected DTC(s). See appropriate SELF-DIAGNOSTICS article.

Ignition System Diagnosis (All Models)

1. If diagnostic system check has already been performed, go to next step. If diagnostic system check has not been performed, go to DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS in appropriate SELF-DIAGNOSTICS article.
2. Check fuses which supply ignition 1 voltage to the Ignition Control Module (ICM) and PCM. If either fuse is open, locate and repair short to ground in the affected circuit. See WIRING DIAGRAMS article. Did you find and correct the condition? If yes, go to step 33 . If no, go to next step.
3. Connect a scan tool. Turn ignition on, with engine off. Select the Engine Data 1 display on scan tool. Observe engine RPM while cranking engine. Does scan tool indicate an engine RPM? If yes, go to step 15 . If no, go to next step.
4. Turn ignition off. Disconnect ICM connector. Turn ignition on. Connect a test light between the ignition positive feed terminal and ground terminal in the ICM connector. Does the test light illuminate? If yes, go to step 6 . If no, go to next step.
5. Leave the ICM connector disconnected. Connect test light between ICM ignition 1 voltage and engine ground. Does the test light illuminate? If yes, go to step 28 . If no, go to step 29 .
6. Turn ignition off. Reconnect the ICM connector. Disconnect the Crankshaft Position (CKP) sensor. Turn ignition on. Connect a DVOM between the 10-volt reference terminal and ground terminal in the CKP sensor connector. Does the voltage about battery voltage. If yes, go to next step. If no, go to step 9 .
7. Connect the DVOM between the CKP sensor 1 signal terminal and ground terminal in connector. Does voltage measure within 6-8 volts? If yes, go to next step. If no, go to step 12 .
8. Check for faulty terminal connections at the CKP sensor. Repair any connections if necessary. Did you find and correct the condition? If yes, go to step 33 . If no, go to step 31 .
9. Connect the DVOM between the CKP 10-volt reference circuit and engine ground. Does the voltage measure about battery voltage. If yes, go to next step. If no, go to step 11 .
10. Turn ignition off. Leave the CKP sensor disconnected. Disconnect the ICM connector. Test the CKP sensor ground for an open. Repair the circuit if necessary. Did you find and correct the condition? If yes, go to step 33 . If no, go to step 27 .
11. Turn ignition on. Leave the CKP sensor disconnected. Disconnect the ICM connector. Test the CKP 10-volt reference circuit for an open and for a short to ground. Repair circuit if necessary. If yes, go to step 33 . If no, go to step 27 .
12. Leave the DVOM connected. Turn ignition off. Disconnect ICM connector. Turn ignition on. Does the voltage measure about battery voltage? If yes, go to next step. If no, go to step 14 .
13. Locate and repair the short to voltage in the CKP sensor 1 signal circuit. After repairs, go to step 33 .
14. Test the CKP sensor 1 signal circuit for an open, short to ground or a short to sensor ground Repair the circuit if necessary. Did you find and correct the condition? If yes, go to step 33 . If no, go to step 27 .
15. Turn ignition off. Disconnect a spark plug wire from a spark plug. Install Spark Tester (J-26792) in the end of the spark plug wire. Jump the companion cylinder's ignition wire to engine ground. The companion cylinder is the cylinder that shares the same ignition coil . Crank engine while observing the spark tester . A spark should be observed. Repeat the test for each ignition wire, noting any cylinders that DO NOT have spark. Do all of the cylinders have spark? If yes, go to step 25 . If no, go to next step.
16. Do any of the cylinders have spark? If yes, go to step 21 . If no, go to next step.
17. Turn ignition off. Disconnect the CKP sensor connector. Turn ignition on. Connect the DVOM between the CKP sensor 2 signal circuit and ground. Does the voltage measure within 6-8 volts? If yes, go to next step. If no, go to step 19 .
18. Test for faulty terminal connections at the CKP sensor. Repair any terminals as necessary. Did you find and correct the condition? If yes, go to step 33 . If no, go to step 30 .
19. Turn ignition off. Disconnect the ICM connector. Turn ignition on. Test the CKP sensor 2 signal circuit for a short to voltage or a short to the sensor 10-volt reference circuit. Repair the circuit as necessary. Did you find and correct the condition? If yes, go to step 33 . If no, go to next step.
20. Test CKP sensor 2 signal circuit for a short to ground and for a short to sensor ground. Check for open CKP sensor 2 signal circuit. Repair as necessary. Did you find and correct the condition? If yes, go to step 33 . If no, go to step 27 .
21. Inspect the ignition coils and ignition wires associated with the cylinders that did not have spark. Verify that the ignition components are free of cracks and carbon tracking. Replace any damaged ignition components. Did you find and correct the condition? If yes, go to step 33 . If no, go to next step.
22. Measure the secondary resistance of ignition coils. If any of the ignition coil resistance is not within 5000-8000 ohms? If yes, go to step 33 . If no, go to next step.
23. Measure the resistance of the ignition wires associated with the cylinders that did not have spark. Replace ignition wires that have a resistance of greater than 3000 ohms/ft. Did you find and correct the condition? If yes, go to step 33 . If no, go to next step.
24. Remove coils associated with the cylinder that did not have spark. Connect a test light across the ignition module primary circuit, between the ICM terminals, for the coils. Observe test light while cranking engine. Does test light flash continuously while engine is being cranked? If yes, go to step 32 . If no, go to step 31 .
25. Remove spark plugs from all of the cylinders. Inspect spark plug electrodes. Are any of the spark plugs fouled? If yes, diagnose for and engine mechanical problem. If no, go to next step.
26. Check for a short between CKP sensor 1 and CKP sensor 2 signal inputs to ICM. Check for short between the medium resolution and low resolution engine speed signal inputs to PCM. If a problem is found, repair as necessary. Did you find and correct the condition? If yes, go to step 33 . If no, diagnose for an engine mechanical problem.
27. Check for faulty terminal connections at ICM. Repair any terminals as necessary. Did you find and correct the condition? If yes, go to step 33 . If no, go to step 31 .
28. Locate and repair an open in ICM ground circuit. After repairs, go to step 33 .
29. Locate and repair an open in the ignition 1 voltage circuit to ICM. After repairs, go to step 33 .
30. Replace CKP sensor. After replacing sensor, go to step 33 .
31. Replace the ignition control module. After replacing module, go to step 33 .
32. Replace the ignition coils associated with the cylinders that did not have spark. After replacing ignition coil(s), go to next step.
33. Remove all test equipment. Connect any disconnected components. Turn ignition off for 30 seconds. Start engine and operate vehicle. Observe the MIL and note the vehicle performance and driveability. Does the vehicle operate normally, with no MIL and no stored DTCs? If yes, system is okay. If no, go to step 2 .

Fuel Pump Electrical Circuit (VIN K - Grand Prix)

1. If diagnostic system check has already been performed, go to next step. If diagnostic system check has not been performed, go to DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS in appropriate SELF-DIAGNOSTICS article.
2. Connect scan tool. Turn ignition on. Using scan tool, command fuel pump relay on and off. If fuel pump turns on and off, check for intermittent problem. See appropriate TROUBLE SHOOTING - NO CODES article. If fuel pump does not turn on and off, go to next step.
3. Using scan tool, command fuel pump relay on and off. If fuel pump relay clicks, go to step 9 . If fuel pump relay does not click, go to next step.
4. Turn ignition off. Disconnect fuel pump relay located in underhood fuse block. Turn ignition on. Using test light connected to ground, probe fuel pump relay control circuit. Using scan tool, command fuel pump relay on and off. If test light turns on and off, go to next step. If test light does not turn on and off, go to step 6 .
5. Connect test light between fuel pump relay control circuit and fuel pump relay ground circuit at relay cavities. Using scan tool, command fuel pump relay on. If test light turns on and off, go to step 19 . If test light does not turn on and off, go to step 22 .
6. If test light remains illuminated with each command, go to next step. If test light does not remain illuminated with each command, go to step 8 .
7. Disconnect PCM. Check fuel pump relay control circuit for short to voltage. Repair as necessary. After repairs, go to step 27 . If circuit is okay, go to step 26 .
8. Disconnect PCM. Check fuel pump relay control circuit for open or short to ground. Repair as necessary. After repairs, go to step 27 . If circuit is okay, go to step 20 .
9. Turn ignition on. If fuel pump runs continuously, go to next step. If fuel pump does not run continuously, go to step 11 .
10. Turn ignition off. Disconnect fuel pump relay located in underhood fuse block. Turn ignition on. If fuel pump runs continuously, go to step 21 . If fuel pump does not run continuously, go to step 25 .
11. Check F/PMP fuse (20-amp) located in underhood fuse block. If fuse is open, go to next step. If fuse is okay, go to step 14 .
12. Remove fuel pump access panel. Check for short to ground in fuel pump power feed circuit between F/PMP fuse and fuel pump. Repair as necessary. After repairs, go to step 27 . If circuit is okay, go to next step.
13. Reconnect all components. Install NEW F/PMP fuse. Using scan tool, command fuel pump relay on. If fuse blows, go to step 24 . If fuse does not blow, check for intermittent problem. See appropriate TROUBLE SHOOTING - NO CODES article.
14. Turn ignition off. Disconnect fuel pump relay located in underhood fuse block. Turn ignition on. Using test light connected to ground, probe fuel pump relay ignition feed circuit at relay cavity. If test light illuminates, go to next step. If test light does not illuminate, go to step 23 .
15. Connect fused jumper wire between fuel pump relay ignition feed circuit and fuel pump power feed circuit at relay cavities. If fuel pump runs, go to step 19 . If fuel pump does not run, go to next step.
16. Remove fuel pump access panel. Check for open or high resistance in fuel pump power feed circuit between fuel pump relay and fuel pump. Repair as necessary. After repairs, go to step 27 . If circuit is okay, go to next step.
17. Check for open or high resistance in fuel pump ground circuit. Repair as necessary. After repairs, go to step 27 . If circuit is okay, go to next step.
18. Check for poor connections at fuel pump. Repair as necessary. After repairs, go to step 27 . If connections are okay, go to step 24 .
19. Check for poor connections at fuel pump relay. Repair as necessary. After repairs, go to step 27 . If connections are okay, go to step 25 .
20. Check for poor connections at PCM. Repair as necessary. After repairs, go to step 27 . If connections are okay, go to step 26 .
21. Repair short to voltage in fuel pump power feed circuit. After repairs, go to step 27 .
22. Repair open in fuel pump relay ground circuit. After repairs, go to step 27 .
23. Repair open in fuel pump relay ignition feed circuit. After repairs, go to step 27 .
24. Replace fuel pump. After repairs, go to step 27 .
25. Replace fuel pump relay. After repairs, go to step 27 .
26. Replace PCM. Perform PCM relearn procedure. After repairs, go to next step.
27. Operate system to verify repair. If system operation is okay, testing is complete. If system operation is not okay, go to step 2 .

Fuel Pump Electrical Circuit (Except VIN K - Grand Prix)

1. If diagnostic system check has already been performed, go to next step. If diagnostic system check has not been performed, go to DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS in appropriate SELF-DIAGNOSTICS article.
2. Install a scan tool. Turn ignition on, with engine off. With scan tool, command fuel pump relay on and off. Does fuel pump turn on and off? If yes, problem is intermittent. If yes, go to next step.
3. With a scan tool, command the fuel pump relay on and off. Do you hear a click when you command the fuel pump relay on and off? If yes, go to step 9 . If no, go to next step.
4. Turn ignition off. Disconnect fuel pump relay. Turn ignition on, with engine off. Probe the control circuit of the fuel pump relay with a test light connected to a good ground. With scan tool, command fuel pump relay on and off. Does the test light turn on and off? If yes, go to next step. If no, go to step 6 .
5. Connect a test light between the control circuit of fuel pump relay and ground circuit of the fuel pump relay. With scan tool, command fuel pump relay on and off. Does test light turn on and off? If yes, go to step 19 . If no, go to step 22 .
6. Does test light remain illuminated with each command? If yes, go to next step. If no, go to step 8 .
7. Test 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 .
8. Test the control circuit of the fuel pump relay 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 .
9. Turn ignition on, with engine off. Does the fuel pump operate continuously? If yes, go to next step. If no, go to step 11 .
10. Turn ignition off. Disconnect fuel pump relay. Turn ignition on, with engine off. Does fuel pump operate continuously? If yes, go to step 21 . If no, go to step 25 .
11. Is fuel pump fuse open? If yes, go to next step. If no, go to step 14 .
12. Test fuel pump supply voltage circuit for a grounded circuit between fuel pump fuse and fuel pump. Replace fuel pump fuse if necessary. Did you find and correct the condition? If yes, go to step 27 . If no, go to next step.
13. Install all disconnected electrical components. Install a new fuel pump fuse. With scan tool, turn fuel pump on. Is fuel pump fuse open? If yes, go to step 24 . If no, problem is intermittent.
14. Turn ignition off. Disconnect fuel pump relay. Turn ignition on, with engine off. Probe the battery voltage circuit of fuel pump relay switch with 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 .
15. Connect a 20-amp fused jumper wire between the battery voltage circuit of fuel pump relay switch and supply voltage circuit of the fuel pump. Does the fuel pump operate? If yes, go to step 19 . If no, go to next step.
16. Test the supply voltage circuit of the fuel pump 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.
17. 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.
18. Inspect for poor connections at fuel pump. Did you find and correct the condition? If yes, go to step 27 . If no, go to step 24 .
19. Inspect for poor connections at fuel pump relay. Did you find and correct the condition? If yes, go to step 27 . If no, go to step 25 .
20. Inspect for poor connections at PCM harness connector. Did you find and correct the condition? If yes, go to step 27 . If no, go to step 26 .
21. Repair fuel pump supply voltage circuit for short to voltage. After repairs, go to step 27 .
22. Repair open fuel pump relay ground circuit. After repairs, go to step 27 .
23. Repair battery voltage circuit of fuel pump relay switch. After repairs, go to step 27 .
24. Replace fuel pump. Replace fuel pump fuse, if necessary. After replacing fuel pump, go to step 27 .
25. Replace fuel pump relay. After replacing relay, go to step 27 .
26. Replace PCM. After replacing PCM, go to next step.
27. Operate the system in order to verify the repair. Did you correct the condition? If yes, system is okay. If no, go to step 2 .

Fuel System Diagnosis (All Models)

1. If diagnostic system check has already been performed, go to next step. If diagnostic system check has not been performed, go to DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS in appropriate SELF-DIAGNOSTICS article.
2. Turn ignition on, with engine off. Command fuel pump on with scan tool. Does fuel pump operate? If yes, go to next step. If no, go to «FUEL PUMP ELECTRICAL CIRCUIT (VIN K - GRAND PRIX)»(/buick/lesabre/viii-2000-2005/remont/testing-diagnostics/#engine-control-system-basic-diagnostic-procedures__fuel-pump-electrical-circuit-vin-k) or «FUEL PUMP ELECTRICAL CIRCUIT (EXCEPT VIN K - GRAND PRIX)»(/buick/lesabre/viii-2000-2005/remont/testing-diagnostics/#engine-control-system-basic-diagnostic-procedures__fuel-pump-electrical-circuit-except-vin) .
3. Turn ignition on. Turn off all accessories. Install fuel pressure gauge. Turn ignition on, with engine off. The fuel pump may need to be commanded on a few times in order to obtain the highest possible fuel pressure. DO NOT start engine. Command fuel pump on with scan tool. Observe the fuel pressure gauge with fuel pump commanded on. Is fuel pressure within 48-54 psi (3.4-3.8 kg/cm 2 ). If yes, go to next step. If no, go to step 12 .
4. Monitor fuel pressure gauge for one minute. Does fuel pressure decrease by more than 5 psi (0.4 kg/cm 2 ). If yes, go to step 9 . If no, go to next step.
5. Relieve fuel pressure to 10 psi (0.7 kg/cm 2 ). Monitor fuel pressure gauge for 5 minutes. Does fuel pressure decrease by more than 2 psi (0.1 kg/cm 2 ). If yes, go to step 24 . If no, go to next step.
6. Turn ignition off for 15 seconds. Turn ignition on, with engine off. Monitor fuel pressure gauge. Start engine. Does fuel pressure decrease by 3-10 psi (0.2-0.7 kg/cm 2 ) after engine starts? If yes, go to next step. If no, go to step 8 .
7. Operate vehicle within the conditions of the customer's concern. Monitor fuel related parameters with scan tool. Do any of the scan tool parameters indicate a lean condition? If yes, go to step 17 . If no, see appropriate TROUBLE SHOOTING - NO CODES article.
8. Disconnect vacuum hose from the fuel pressure regulator. Monitor fuel pressure gauge. Operate engine at idle. Using a hand-held vacuum pump, apply 12-14 in. Hg (14-47 kPa). Does fuel pressure decrease by 3-10 psi (0.2-0.7 kg/cm 2 ) when vacuum is applied? If yes, go to step 21 . If no, go to step 23 .
9. Turn ignition off. Remove vacuum hose from fuel pressure regulator. Turn ignition on, with engine off. Command fuel pump on with scan tool. Inspect for a fuel leak from vacuum port of fuel pressure regulator. Is fuel pressure regulator leaking fuel? If yes, go to step 23 . If no, go to next step.
10. Turn ignition off. Relieve fuel pressure. Disconnect fuel feed hose and fuel return hose from fuel rail pipes. Install a Fuel Pipe Shut-off Adapter (J-37287) between fuel pipe, fuel hoses and fuel rail pipes. Open the valves on the shut-off adapters on fuel pipe. Turn ignition on, with engine off. Command fuel pump on with scan tool. Bleed air from fuel pressure gauge. Command fuel pump on and then off with a scan tool. Close shut-off valve on fuel feed pipe. Monitor fuel pressure gauge for one minute. Does fuel pressure remain constant? If yes, go to step 19 . If no, go to next step.
11. Turn ignition off. Open the shut-off valve on the fuel feed pipe. Turn ignition on, with engine off. Command the fuel pump on and then off with scan tool. Close the shut-off valve on the fuel return pipe. Monitor the fuel pressure gauge for one minute. Does fuel pressure remain constant? If yes, go to step 23 . If no, go to step 20 .
12. Is fuel pressure more than 54 psi (3.8 kg/cm 2 ). If yes, go to step 14 . If no, go to next step.
13. Is fuel pressure more than zero psi? If yes, go to step 16 . If no, go to step 17 .
14. Turn ignition off. Relieve fuel pressure. Disconnect fuel return hose from fuel rail pipe. Attach a length of a flexible fuel hose to fuel rail outlet passage. Place open end of the flexible fuel hose into an approved gasoline container. Turn ignition on, with engine off. Monitor fuel pressure gauge with fuel pump operating. Is fuel pressure within 48-54 psi (3.4-3.8 kg/cm 2 ). If yes, go to step 22 . If no, go to next step.
15. Inspect the fuel rail return pipe and the fuel rail outlet passage for a restriction. Did you find and correct the condition? If yes, go to step 25 . If no, go to step 23 .
16. Turn ignition off. Relieve fuel pressure. Disconnect fuel return hose from fuel rail pipe. Install Fuel Shut-Off Adapter (J-37287) between the fuel return pipe and fuel rail. Open valve in fuel pipe shut-off adapter. Turn ignition on, with engine off. Bleed air from fuel system. Monitor fuel pressure gauge. DO NOT allow fuel pressure to exceed 75 psi (5.3 kg/cm 2 ). Excessive pressure may damage fuel system. Slowly close the valve in the fuel return pipe shut-off adaptor. Command the fuel pump on with scan tool. Does the fuel pressure increase to more than 54 psi (3.8 kg/cm 2 ). If yes, go to step 23 . If no, go to next step.
17. Inspect for a restriction in the fuel filter or fuel feed pipe Did you find and correct the condition? If yes, go to step 25 . If no, go to next step.
18. Inspect fuel pump harness connectors and ground circuits for poor connections. Did you find and correct the condition? If yes, go to step 25 . If no, go to next step.
19. Remove fuel sender assembly. Inspect the fuel pump flexible hose for damage and the harness connectors on the in-tank fuel pump for poor connections. Check fuel strainer for restriction and fuel tank for contamination. Did you find and correct the condition? If yes, go to step 25 . If no, go to step 24 .
20. Turn ignition off. Raise fuel rail without removing the fuel lines. Turn ignition on, with engine off. Command fuel pump on with scan tool. Locate and replace leaking fuel injector. After repairs, go to step 25 .
21. Repair the vacuum source to fuel pressure regulator. After repairs, go to step 25 .
22. Locate and repair restricted fuel return pipe. After repairs, go to step 25 .
23. Before replacing fuel pressure regulator, inspect for a missing or for a damaged "O" ring seal. Replace fuel pressure regulator. After replacing fuel pressure regulator, go to step 25 .
24. Replace fuel pump. After replacing fuel pump, go to next step.
25. Operate the system in order to verify the repair. Did you correct the condition? If yes, system is okay. If no, go to step 3 .

Fuel Injector Circuit (VIN K - Camaro, Firebird, Impala & Monte Carlo)

1. If diagnostic system check has already been performed, go to next step. If diagnostic system check has not been performed, go to DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS in appropriate SELF-DIAGNOSTICS article.
2. Are any fuel injector DTCs set? If yes, diagnose DTC P0201-P0206. See appropriate SELF-DIAGNOSTICS article. If no, go to next step.
3. Inspect fuel injector fuse (located in underhood fuse/relay block). Is fuel injector fuse open? If yes, go to next step. If no, go to step 6 .
4. Turn ignition off. Disconnect the fuel injector multi-way harness connector. Using a test light connected to battery voltage, probe the ignition 1 voltage supply circuit of the fuel injector (fuse side). See WIRING DIAGRAMS article. Does the test light illuminate? If yes, go to step 9 . If no, go to next step.
5. Turn ignition on, with engine off. Does the test light illuminate? If yes, go to step 13 . If no, go to step 8 .
6. Turn ignition off. Disconnect fuel injector multi-way harness connector. Turn ignition on, with engine off. Probe the ignition 1 voltage supply circuit of the fuel injector with a test light connected to a good ground. Does the test light illuminate? If yes, go to next step. If no, go to step 10 .
7. Test for continuity between the ignition 1 voltage supply terminal and a fuel injector terminal, at the fuel injector multi-way harness connector. Does DVOM display OL? If yes, go to step 11 . If no, go to step 12 .
8. Test the ignition 1 voltage supply circuit of the fuel injector, between the multi-way harness connector and the fuel injectors for a short to ground. Did you find and correct the condition? If yes, go to step 14 . If no, problem is intermittent.
9. Repair the short to ground in the ignition 1 voltage supply circuit of the fuel injector. After repairs, go to step 14 .
10. Repair the open in the ignition 1 voltage supply circuit between the underhood electrical center and splice S109. See WIRING DIAGRAMS article. After repairs, go to step 14 .
11. Repair the ignition 1 voltage supply circuit of the fuel injectors for an open and/or high resistance between the multi-way connector and splice. After repairs, go to step 14 .
12. Repair the poor connection at the multi-way connector. After repairs, go to step 14 .
13. Repair short to PCM ground in the ignition 1 voltage supply circuit of the fuel injector. After repairs, go to next step.
14. Operate the system in order to verify the repair. Did you correct the condition? If yes, system is okay. If no, go to step 3 .

Fuel Injector Circuit Diagnosis (VIN K & 1 - Bonneville, Grand Prix, LeSabre & Park Avenue)

1. If diagnostic system check has already been performed, go to next step. If diagnostic system check has not been performed, go to DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS in appropriate SELF-DIAGNOSTICS article.
2. Are any fuel injector DTCs set? If yes, diagnose DTC P0201-P0206. See appropriate SELF-DIAGNOSTICS article. If no, go to next step.
3. Inspect the fuel injector fuse. Fuse is located in underhood fuse block. Is fuel injector fuse open? If yes, go to next step. If no, go to DTC P034. See appropriate SELF-DIAGNOSTICS article.
4. Turn ignition off. Disconnect a fuel injector electrical connector. Probe the ignition 1 voltage supply circuit of the fuel injector with a test light connected to battery voltage. Does test light illuminate? If yes, go to next step. If no, go to step 6 .
5. Test the ignition 1 voltage supply circuit of the fuel injector between the fuel injector fuse and fuel injectors for a short to ground. See WIRING DIAGRAMS article. Did you find and correct the condition? If yes, go to step 7 . If no, problem is intermittent. See appropriate TROUBLE SHOOTING - NO CODES article.
6. Inspect for poor connections at fuel injector harness connector. Did you find and correct the condition? If yes, go to next step. If no, problem is intermittent. See appropriate TROUBLE SHOOTING - NO CODES article.
7. Operate the system in order to verify the repair. Did you correct the condition? If yes, system is okay. If no, go to step 3 .

Fuel Injector Circuit Diagnosis (VIN K & 1 - Regal)

1. If diagnostic system check has already been performed, go to next step. If diagnostic system check has not been performed, go to DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS in appropriate SELF-DIAGNOSTICS article.
2. Are any fuel injector DTCs set? If yes, go to DTC P0201-P0206. See appropriate SELF-DIAGNOSTICS article. If no, go to next step.
3. Inspect the fuel injector fuse. Fuse is located in underhood fuse/relay block. Is fuel injector fuse open? If yes, go to next step. If no, go to step 5 .
4. Turn ignition off. Disconnect a fuel injector harness connector. Turn ignition on, with engine off. Using a test light connected to battery voltage, probe the ignition 1 voltage supply circuit of a fuel injector. Does test light illuminate? If yes, go to step 6 . If no, problem is intermittent. See TROUBLE SHOOTING - NO CODES article.
5. Turn ignition off. Disconnect a fuel injector harness connector. Turn ignition on, with engine off. Probe the ignition 1 voltage supply circuit of the fuel injector with test light connected to a good ground. Does the test light illuminate? If yes, go to DTC P0341. See appropriate SELF-DIAGNOSTICS article. If no, go to step 7 .
6. Test the ignition 1 voltage supply circuit of each fuel injector for a short to ground. Replace the fuse. After repairs, go to step 8 .
7. Repair open or poor connection in the ignition 1 voltage supply circuit of the 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, go to step 3 .

NO START - ENGINE CRANKS OKAY (4.6L)

Note. Before performing the following tests, check battery condition, engine cranking speed and for adequate fuel in tank.

1. Ensure proper starting procedure is being used. Visually check vacuum hoses for splits, kinks and proper connections, as shown on Vehicle Emission Control Information (VECI) label. Check ignition wires for cracking, hardness and proper connections at both coil pack and spark plugs.
2. Remove spark plugs. Check and replace as necessary. In very cold temperatures, ensure oil is proper viscosity and not contaminated with gasoline.

1. If diagnostic system check has already been performed, go to next step. If diagnostic system check has not been performed, go to DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS in appropriate SELF-DIAGNOSTICS article.
2. If DTCs P0335, P0340 and P0385 are set, go to next step. If listed DTCs are not set, go to step 4 .
3. Check for short to ground in CKP and CMP ignition feed circuits, or shorted CKP or CMP sensors. Repair as necessary. After repairs, go to step 12 .
4. Check all fuses supplying ignition voltage to each ignition control assembly and fuel injectors. If a fuse is open, repair short to ground in affected circuit and replace fuse. After repairs, go to step 12 . If fuses are okay, go to next step.
5. Using scan tool, check for skewed TP sensor or ECT sensor. Check for skewed or unresponsive MAP sensor. Repair as necessary. After repairs, go to step 12 . If sensors are okay, go to next step.
6. Turn ignition off. Connect fuel pressure gauge. See «BASIC FUEL SYSTEM CHECKS»(/buick/lesabre/viii-2000-2005/remont/testing-diagnostics/#engine-control-system-basic-diagnostic-procedures__basic-fuel-system-checks) . Turn ignition on. Check fuel pressure. If pressure is 41-47 psi (2.9-3.3 kg/cm 2 ), go to step 8 . If pressure is not as specified, go to next step.
7. If fuel pressure is indicated, check fuel system. See FUEL SYSTEMS in appropriate SYSTEM & COMPONENT TESTING article. If fuel pressure is not indicated, go to «FUEL PUMP ELECTRICAL CIRCUIT»(/buick/lesabre/viii-2000-2005/remont/testing-diagnostics/#engine-control-system-basic-diagnostic-procedures) .
8. Check for faulty MAF sensor. Replace if necessary. After repairs, go to step 12 . If MAF sensor is okay, go to next step.
9. Check for fouled spark plugs. Replace if necessary. After repairs, go to step 12 . If spark plugs are okay, go to next step.
10. Check for faulty splice connection in battery feed circuit to both ignition control module assemblies. Repair as necessary. After repairs, go to step 12 . If circuit is okay, go to next step.
11. Check for engine mechanical problems. Repair as necessary. After repairs, go to next step. If no problem is found, check for intermittent problem. See appropriate TROUBLE SHOOTING - NO CODES article.
12. Using scan tool, clear DTCs. Attempt to start engine. If engine starts and runs, go to next step. If engine does not start, go to step 2 .
13. Allow engine to reach normal operating temperature. Using scan tool, check for DTCs. If any DTCs set, diagnose DTCs. See appropriate SELF-DIAGNOSTICS article. If no DTCs are set, system is okay.

1. If diagnostic system check has already been performed, go to next step. If diagnostic system check has not been performed, go to DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS in appropriate SELF-DIAGNOSTICS article.
2. Connect scan tool. Turn ignition on. Using scan tool, command fuel pump relay on and off. If fuel pump turns on and off, check for intermittent problem. See appropriate TROUBLE SHOOTING - NO CODES article. If fuel pump does not turn on and off, go to next step.
3. Using scan tool, command fuel pump relay on and off. If fuel pump relay clicks, go to step 9 . If fuel pump relay does not click, go to next step.
4. Turn ignition off. Disconnect fuel pump relay located in rear fuse block. Turn ignition on. Using test light connected to ground, probe fuel pump relay control circuit at relay cavity. Using scan tool, command fuel pump relay on and off. If test light turns on and off, go to next step. If test light does not turn on and off, go to step 6 .
5. Connect test light between fuel pump relay control circuit and fuel pump relay ground circuit at relay cavities. Using scan tool, command fuel pump relay on and off. If test light turns on and off, go to step 19 . If test light does not turn on and off, go to step 22 .
6. If test light remains illuminated with each command, go to next step. If test light does not illuminate at all, go to step 8 .
7. Disconnect PCM. Check for short to voltage in fuel pump relay control circuit. Repair as necessary. After repairs, go to step 27 . If circuit is okay, go to step 26 .
8. Disconnect PCM. Check for open or short to ground in fuel pump relay control circuit. Repair as necessary. After repairs, go to step 27 . If circuit is okay, go to step 20 .
9. Turn ignition on. If fuel pump runs continuously, go to next step. If fuel pump does not run continuously, go to step 11 .
10. Turn ignition off. Disconnect fuel pump relay located in rear fuse block. Turn ignition on. If fuel pump runs continuously, go to step 21 . If fuel pump does not run continuously, go to step 25 .
11. Check F/PMP fuse (20-amp) located in rear fuse block. If fuse is open, go to next step. If fuse is okay, go to step 14 .
12. Remove fuel pump access panel. Check for short to ground in fuel pump power feed circuit between fuel pump and fuse. Repair as necessary. After repairs, go to step 27 . If circuit is okay, go to next step.
13. Reconnect all components. Install NEW F/PMP fuse. Using scan tool, command fuel pump relay on. If fuse blows, go to step 24 . If fuse does not blow, check for intermittent problem. See appropriate TROUBLE SHOOTING - NO CODES article.
14. Turn ignition off. Disconnect fuel pump relay located in rear fuse block. Turn ignition on. Using test light connected to ground, probe fuel pump relay battery feed circuit at relay cavity. If test light illuminates, go to next step. If test light does not illuminate, go to step 23 .
15. Connect fused jumper wire between fuel pump relay battery feed circuit and fuel pump power feed circuit at relay cavities. If fuel pump runs, go to step 19 . If fuel pump does not run, go to next step.
16. Remove fuel pump access panel. Check for open or high resistance in fuel pump power feed circuit between fuel pump relay and fuel pump. Repair as necessary. After repairs, go to step 27 . If circuit is okay, go to next step.
17. Check for open, high resistance or poor connection in fuel pump ground circuit at ground splice connector. Repair as necessary. After repairs, go to step 27 . If circuit is okay, go to next step.
18. Check for poor connections at fuel pump. Repair as necessary. After repairs, go to step 27 . If connections are okay, go to step 24 .
19. Check for poor connections at fuel pump relay. Repair as necessary. After repairs, go to step 27 . If connections are okay, go to step 25 .
20. Check for poor PCM harness connections. Repair as necessary. After repairs, go to step 27 . If connections are okay, go to step 26 .
21. Repair short to voltage in fuel pump power feed circuit. After repairs, go to step 27 .
22. Repair open in fuel pump relay ground circuit. After repairs, go to step 27 .
23. Repair open in fuel pump relay battery feed circuit. After repairs, go to step 27 .
24. Replace fuel pump. After repairs, go to step 27 .
25. Replace fuel pump relay. After repairs, go to step 27 .
26. Replace PCM. Perform PCM relearn procedure. After repairs, go to next step.
27. Operate system to verify repair. If system operation is okay, testing is complete. If system operation is not okay, go to step 2 .

NO START - ENGINE CRANKS OKAY (5.7L)

Note. Before performing the following tests, check battery condition, engine cranking speed and for adequate fuel in tank.

1. Ensure proper starting procedure is being used. Visually check vacuum hoses for splits, kinks and proper connections, as shown on Vehicle Emission Control Information (VECI) label. Check ignition wires for cracking, hardness and proper connections at both coil pack and spark plugs.
2. Remove spark plugs. Check and replace as necessary. In very cold temperatures, ensure oil is proper viscosity and not contaminated with gasoline.

Ignition System Diagnosis ("F" Body)

1. If diagnostic system check has already been performed, go to next step. If diagnostic system check has not been performed, go to DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS in appropriate SELF-DIAGNOSTICS article.
2. Connect scan tool. Crank engine for 15 seconds. If any DTCs set, diagnose them first. See appropriate SELF-DIAGNOSTICS article. If no DTCs are set, go to next step.
3. Using scan tool, monitor VTD fuel enabled status. If scan tool displays ACTIVE, diagnose using diagnostic procedure for DTC P1626. See appropriate SELF-DIAGNOSTICS article. If scan tool does not display ACTIVE, go to next step.
4. Using scan tool, monitor engine speed while cranking engine. If scan tool indicates engine RPM, go to next step. If scan tool does not indicate engine RPM, go to step 6 .
5. Turn ignition on. Using test light connected to ground, probe terminals of the following fuses located in underhood electrical center No. 2: A/C CRUISE ENG CTRL ENG SEN INJR1 INJR2 If test light illuminates on both sides of all fuses, go to step 9 . If test light does not illuminate, diagnose ignition relay circuit. See «IGNITION RELAY CIRCUIT (5.7L)»(/buick/lesabre/viii-2000-2005/remont/testing-diagnostics/#engine-control-system-basic-diagnostic-procedures__ignition-relay-circuit-57l-f) under BASIC IGNITION SYSTEM CHECKS.
6. Disconnect CKP sensor harness connector. Measure voltage between ground and ignition feed circuit at CKP sensor harness connector. If voltage is near battery voltage, go to step 13 . If voltage is not near battery voltage, go to next step.
7. Disconnect CMP sensor harness connector. Measure voltage between ground and ignition feed circuit at CMP sensor connector. If voltage is near battery voltage, go to step 14 . If voltage is not near battery voltage, go to next step.
8. Check for short to ground in CKP and CMP sensor ignition feed circuits. Repair as necessary. After repairs, go to step 16 . If circuits are okay, go to step 15 .
9. Using scan tool, monitor engine coolant temperature. If scan tool value is close to actual engine temperature, go to next step. If scan tool value is not close to actual engine temperature, diagnose using diagnostic procedure for DTC P0118. See appropriate SELF-DIAGNOSTICS article.
10. Using scan tool, command fuel pump on. If fuel pump runs, go to next step. If fuel pump does not run, diagnose fuel pump relay circuit. See «FUEL PUMP ELECTRICAL CIRCUIT ("F" BODY)»(/buick/lesabre/viii-2000-2005/remont/testing-diagnostics/#engine-control-system-basic-diagnostic-procedures__fuel-pump-electrical-circuit-f-body) .
11. Turn ignition off. Connect fuel pressure gauge. See «BASIC FUEL SYSTEM CHECKS»(/buick/lesabre/viii-2000-2005/remont/testing-diagnostics/#engine-control-system-basic-diagnostic-procedures__basic-fuel-system-checks) . Turn ignition on. Check fuel pressure. If pressure is 55-62 psi (3.9-4.4 kg/cm 2 ), go to next step. If pressure is not as specified, diagnose fuel system. See FUEL SYSTEMS in appropriate SYSTEM & COMPONENT TESTING article.
12. Check for air leaks in ducts between MAF sensor and throttle body. Ensure throttle angle is zero percent at closed throttle. A faulty MAF sensor may cause no-start or stalling after start condition. Disconnecting MAF sensor will cause PCM to default to speed density (MAP, IAT and RPM) to calculate load and intake airflow. If fault condition is corrected by disconnecting MAF sensor, or connections are okay, replace MAF sensor. Check if spark plugs are gas fouled by a rich condition. Check for engine mechanical failure causing no-start condition (i.e. timing chain, low compression, etc.). Compare MAP/BARO parameters to a similar vehicle and ensure values are similar. If a problem is found and repaired, go to step 16 . If no problem is found, check for intermittent problem. See appropriate TROUBLE SHOOTING - NO CODES article.
13. Replace CKP sensor. After repairs, go to step 16 .
14. Replace CMP sensor. After repairs, go to step 16 .
15. Replace PCM. Perform PCM relearn procedure. After repairs, go to next step.
16. Using scan tool, clear DTCs. Attempt to start engine. If engine starts and continues to run, go to next step. If engine does not start, or starts and stalls, go to step 2 .
17. Allow engine to reach normal operating temperature. Using scan tool, check for DTCs. If any DTCs are set, diagnose DTCs. See appropriate SELF-DIAGNOSTICS article. If no DTCs are set, go to next step.
18. Using scan tool, select CAPTURE INFO, REVIEW INFO function. Check for any additional DTCs that have not been diagnosed. If additional DTCs are set, diagnose DTCs. See appropriate SELF-DIAGNOSTICS article. If no additional DTCs are set, system is okay.

Ignition System Diagnosis ("Y" Body)

1. If diagnostic system check has already been performed, go to next step. If diagnostic system check has not been performed, go to DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS in appropriate SELF-DIAGNOSTICS article.
2. Turn ignition on. Using test light connected to ground, probe terminals of the following fuses, located in underhood electrical center No. 2: A/C ENG IGN1 INJR1 INJR2 THROT CONT If test light illuminates on both sides of all fuses, go to next step. If test light does not illuminate, diagnose ignition relay circuit. See «IGNITION RELAY CIRCUIT (5.7L)»(/buick/lesabre/viii-2000-2005/remont/testing-diagnostics/#engine-control-system-basic-diagnostic-procedures__ignition-relay-circuit-57l-f) under BASIC IGNITION SYSTEM CHECKS.
3. Using scan tool, check for DTCs. If any DTCs related to Throttle Actuator Control (TAC) system are set, diagnose DTCs. See appropriate SELF-DIAGNOSTICS article. If DTCs are not set, go to next step.
4. Using scan tool, check for DTCs. If any DTCs related to vehicle theft deterrent system are set, this indicates a problem with column lock or VTD fuel enable circuit. See appropriate BODY CONTROL MODULE article in ACCESSORIES & EQUIPMENT. If DTC P0230, P0335, P0336, P0601, P0602, P0604 or P0606 is set, diagnose DTCs. See appropriate SELF-DIAGNOSTICS article. If DTCs are not set, go to next step.
5. Using scan tool, check for DTCs while cranking engine. If DTCs set while cranking engine, diagnose DTCs. See appropriate SELF-DIAGNOSTICS article. If no DTCs set, go to next step.
6. Using scan tool, monitor engine speed while cranking engine. If engine RPM is indicated on scan tool, go to step 10 . If engine RPM is not indicated on scan tool, go to next step.
7. Turn ignition off. Disconnect CKP sensor harness connector. Measure voltage between ground and ignition feed circuit at CKP sensor harness connector. If voltage is near battery voltage, go to step 14 . If voltage is not near battery voltage, go to next step.
8. Disconnect CMP sensor harness connector. Measure voltage between ground and ignition feed circuit at CMP sensor harness connector. If voltage is near battery voltage, go to step 15 . If voltage is not near battery voltage, go to next step.
9. Check for short to ground in CKP sensor and CMP sensor ignition feed circuits. Repair as necessary. After repairs, go to step 17 . If circuits are okay, go to step 16 .
10. Using scan tool, monitor engine coolant temperature. If scan tool value is close to actual engine temperature, go to next step. If scan tool value is not close to actual engine temperature, diagnose using diagnostic procedure for DTC P0118. See appropriate SELF-DIAGNOSTICS article.
11. Using scan tool, command fuel pump on. If fuel pump runs, go to next step. If fuel pump does not run, diagnose fuel pump relay circuit. See «FUEL PUMP ELECTRICAL CIRCUIT ("Y" BODY)»(/buick/lesabre/viii-2000-2005/remont/testing-diagnostics/#engine-control-system-basic-diagnostic-procedures__fuel-pump-electrical-circuit-y-body) .
12. Turn ignition off. Connect fuel pressure gauge. See «BASIC FUEL SYSTEM CHECKS»(/buick/lesabre/viii-2000-2005/remont/testing-diagnostics/#engine-control-system-basic-diagnostic-procedures__basic-fuel-system-checks) . Turn ignition on. Check fuel pressure. If pressure is 55-62 psi (3.9-4.4 kg/cm 2 ), go to next step. If pressure is not as specified, diagnose fuel system. See FUEL SYSTEMS in appropriate SYSTEM & COMPONENT TESTING article.
13. Check for air leaks in ducts between MAF sensor and throttle body. A faulty MAF sensor may cause a no-start or stalling after start condition. Disconnecting MAF sensor will cause PCM to default to speed density (MAP, IAT, RPM) to calculate load and intake airflow. If fault condition is corrected by disconnecting MAF sensor, or connections are okay, replace MAF sensor. Check if spark plugs are gas fouled by a rich condition. Check for engine mechanical failure causing a no-start condition (i.e. timing chain, low compression, etc.). Compare MAP/BARO parameters to a similar vehicle and ensure values are similar. If a problem is found and repaired, go to step 17 . If no problem is found, check for intermittent problem. See appropriate TROUBLE SHOOTING - NO CODES article.
14. Replace CKP sensor. After repairs, go to step 17 .
15. Replace CMP sensor. After repairs, go to step 17 .
16. Replace PCM. Perform PCM relearn procedure. After repairs, go to next step.
17. Using scan tool, clear DTCs. Attempt to start engine. If engine starts and continues to run, go to next step. If engine does not start, or starts and stalls, go to step 2 .
18. Allow engine to reach normal operating temperature. Using scan tool, check for DTCs. If any DTCs are set, diagnose DTCs. See appropriate SELF-DIAGNOSTICS article. If no DTCs are set, go to next step.
19. Using scan tool, select CAPTURE INFO, REVIEW INFO function. Check for any additional DTCs that have not been diagnosed. If additional DTCs are set, diagnose DTCs. See appropriate SELF-DIAGNOSTICS article. If no additional DTCs are set, system is okay.

Fuel Pump Electrical Circuit ("F" Body)

1. If diagnostic system check has already been performed, go to next step. If diagnostic system check has not been performed, go to DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS in appropriate SELF-DIAGNOSTICS article.
2. Connect scan tool. Turn ignition on. Using scan tool, command fuel pump relay on and off. If fuel pump turns on and off, check for intermittent problem. See appropriate TROUBLE SHOOTING - NO CODES article. If fuel pump does not turn on and off, go to next step.
3. Using scan tool, command fuel pump relay on and off. If fuel pump relay clicks, go to step 9 . If fuel pump relay does not click, go to next step.
4. Turn ignition off. Disconnect fuel pump relay located in underhood fuse block. Turn ignition on. Using test light connected to ground, probe fuel pump relay control circuit at relay cavity. Using scan tool, command fuel pump relay on and off. If test light turns on and off, go to next step. If test light does not turn on and off, go to step 6 .
5. Connect test light between fuel pump relay control circuit and fuel pump relay ground circuit at relay cavities. Using scan tool, command fuel pump relay on and off. If test light turns on and off, go to step 21 . If test light does not turn on and off, go to step 24 .
6. If test light remains illuminated for each command, go to next step. If test light does not illuminate at all, go to step 8 .
7. Disconnect PCM. Check fuel pump relay control circuit for short to voltage. Repair as necessary. After repairs, go to step 29 . If circuit is okay, go to step 28 .
8. Disconnect PCM. Check fuel pump relay control circuit for open or short to ground. Repair as necessary. After repairs, go to step 29 . If circuit is okay, go to step 22 .
9. Turn ignition on. If fuel pump runs continuously, go to next step. If fuel pump does not run continuously, go to step 11 .
10. Turn ignition off. Disconnect fuel pump relay located in underhood fuse block. Turn ignition on. If fuel pump runs continuously, go to step 23 . If fuel pump does not run continuously, go to step 27 .
11. Check FUEL PUMP fuse (20-amp) located in underhood junction block. If fuse is open, go to next step. If fuse is okay, go to step 14 .
12. Disconnect fuel pump jumper harness from body pass-through connector. Check for short to ground in fuel pump power feed circuit between fuel pump relay and body pass-through connector. Repair as necessary. After repairs, go to step 29 . If circuit is okay, go to next step.
13. Lower fuel tank. Check fuel pump jumper harness for damage or grounded circuits. Repair as necessary. After repairs, go to step 29 . If jumper harness is okay, go to step 20 .
14. Turn ignition off. Disconnect fuel pump relay located in underhood fuse block. Turn ignition on. Using test light connected to ground, probe fuel pump relay battery feed circuit at relay cavity. If test light illuminates, go to next step. If test light does not illuminate, go to step 25 .
15. Connect fused jumper wire between fuel pump relay battery feed circuit and fuel pump power feed circuit at relay cavities. If fuel pump runs, go to step 21 . If fuel pump does not run, go to next step.
16. Disconnect fuel pump jumper harness from body pass-through connector. Check for open or high resistance in fuel pump power feed circuit between fuel pump relay and body pass-through connector. Repair as necessary. After repairs, go to step 29 . If circuit is okay, go to next step.
17. Check fuel pump ground circuit for open or high resistance between body pass-through connector and chassis ground. Repair as necessary. After repairs, go to step 29 . If circuit is okay, go to next step.
18. Check fuel pump jumper harness for poor connections at body pass-through connector. Repair as necessary. After repairs, go to step 29 . If connections are okay, go to next step.
19. Lower fuel tank. Check fuel pump jumper harness for damage, open circuits and poor connections. Repair as necessary. After repairs, go to step 29 . If jumper harness is okay, go to step 26 .
20. Reconnect and install all components. Install NEW fuel pump fuse. Using scan tool, command fuel pump relay on. If fuse blows, go to step 26 . If fuse does not blow, check for intermittent problem. See appropriate TROUBLE SHOOTING - NO CODES article.
21. Check for poor connections at fuel pump relay. Repair as necessary. After repairs, go to step 29 . If connections are okay, go to step 27 .
22. Check for poor connections at PCM. Repair as necessary. After repairs, go to step 29 . If connections are okay, go to step 28 .
23. Repair short to voltage in fuel pump power feed circuit. After repairs, go to step 29 .
24. Repair open in fuel pump relay ground circuit. After repairs, go to step 29 .
25. Repair open in fuel pump relay battery feed circuit. After repairs, go to step 29 .
26. Replace fuel pump. After repairs, go to step 29 .
27. Replace fuel pump relay. After repairs, go to step 29 .
28. Replace PCM. Perform PCM relearn procedure. After repairs, go to next step.
29. Operate system to verify repair. If system operation is okay, testing is complete. If system operation is not okay, go to step 2 .

Fuel Pump Electrical Circuit ("Y" Body)

1. If diagnostic system check has already been performed, go to next step. If diagnostic system check has not been performed, go to DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS in appropriate SELF-DIAGNOSTICS article.
2. Connect scan tool. Turn ignition on. Using scan tool, command fuel pump relay on and off. If fuel pump turns on and off, check for intermittent problem. See appropriate TROUBLE SHOOTING - NO CODES article. If fuel pump does not turn on and off, go to next step.
3. Using scan tool, command fuel pump relay on and off. If fuel pump relay clicks, go to step 9 . If fuel pump relay does not click, go to next step.
4. Turn ignition off. Disconnect fuel pump relay located in underhood fuse block. Turn ignition on. Using test light connected to ground, probe fuel pump relay control circuit at relay cavity. Using scan tool, command fuel pump relay on and off. If test light turns on and off, go to next step. If test light does not turn on and off, go to step 6 .
5. Connect test light between fuel pump relay control circuit and fuel pump relay ground circuit at relay cavities. Using scan tool, command fuel pump relay on and off. If test light turns on and off, go to step 19 . If test light does not turn on and off, go to step 22 .
6. If test light remains illuminated with each command, go to next step. If test light does not illuminate at all, go to step 8 .
7. Disconnect PCM. Check for short to voltage in fuel pump relay control circuit. Repair as necessary. After repairs, go to step 27 . If circuit is okay, go to step 26 .
8. Disconnect PCM. Check for open or short to ground in fuel pump relay control circuit. Repair as necessary. After repairs, go to step 27 . If circuit is okay, go to step 20 .
9. Turn ignition on. If fuel pump runs continuously, go to next step. If fuel pump does not run continuously, go to step 11 .
10. Turn ignition off. Disconnect fuel pump relay located in underhood fuse block. Turn ignition on. If fuel pump runs continuously, go to step 21 . If fuel pump does not run continuously, go to step 25 .
11. Check F/PMP fuse (20-amp) located in underhood fuse block. If fuse is open, go to next step. If fuse is okay, go to step 14 .
12. Check for short to ground in fuel pump power feed circuit between fuel pump and fuse. Repair as necessary. After repairs, go to step 27 . If circuit is okay, go to next step.
13. Reconnect all components. Install NEW F/PMP fuse. Using scan tool, command fuel pump relay on. If fuse blows, go to step 24 . If fuse does not blow, check for intermittent problem. See appropriate TROUBLE SHOOTING - NO CODES article.
14. Turn ignition off. Disconnect fuel pump relay located in underhood fuse block. Turn ignition on. Using test light connected to ground, probe fuel pump relay battery feed circuit at relay cavity. If test light illuminates, go to next step. If test light does not illuminate, go to step 23 .
15. Connect fused jumper wire between fuel pump relay battery feed circuit and fuel pump power feed circuit at relay cavities. If fuel pump runs, go to step 19 . If fuel pump does not run, go to next step.
16. Check for open or high resistance in fuel pump power feed circuit between fuel pump relay and fuel pump. Repair as necessary. After repairs, go to step 27 . If circuit is okay, go to next step.
17. Check for open or high resistance in fuel pump ground circuit. Repair as necessary. After repairs, go to step 27 . If circuit is okay, go to next step.
18. Check for poor connections at fuel pump. Repair as necessary. After repairs, go to step 27 . If connections are okay, go to step 24 .
19. Check for poor connections at fuel pump relay. Repair as necessary. After repairs, go to step 27 . If connections are okay, go to step 25 .
20. Check for poor PCM harness connections. Repair as necessary. After repairs, go to step 27 . If connections are okay, go to step 26 .
21. Repair short to voltage in fuel pump power feed circuit. After repairs, go to step 27 .
22. Repair open in fuel pump relay ground circuit. After repairs, go to step 27 .
23. Repair open in fuel pump relay battery feed circuit. After repairs, go to step 27 .
24. Replace fuel pump. After repairs, go to step 27 .
25. Replace fuel pump relay. After repairs, go to step 27 .
26. Replace PCM. Perform PCM relearn procedure. After repairs, go to next step.
27. Operate system to verify repair. If system operation is okay, testing is complete. If system operation is not okay, go to step 2 .

BASIC FUEL SYSTEM CHECKS

Note. For fuel pump circuit testing, see appropriate diagnostic procedure under NO-START DIAGNOSIS .

FUEL SYSTEM PRESSURE RELIEF (EXCEPT SATURN)

Fuel system is under pressure. Pressure must be relieved prior to servicing fuel system. Fuel pressure may be relieved by using one of the following methods

1. On 2.2L and 2.4L, loosen fuel filler cap. Disconnect fuel pump harness connector. Start engine and allow it to run until it stalls. Crank starter for 3 seconds to remove remaining fuel from fuel lines. Turn ignition off. Reconnect fuel pump harness connector. Disconnect negative battery cable to avoid possible fuel discharge in accidental attempt to start engine.
2. On all engines except 2.2L and 2.4L, disconnect negative battery cable. Loosen fuel filler cap. Install Fuel Pressure Gauge (J-34730-1A) on fuel pressure connector of fuel rail. Wrap shop towel around pressure connection when installing fuel pressure gauge to absorb fuel leakage. Install gauge bleed hose in container. Open bleed valve to bleed fuel pressure.

FUEL SYSTEM PRESSURE RELIEF (SATURN)

Fuel pressure may be relieved by using one of following methods

1. Connect scan tool. Start engine. Select SPECIAL TESTS, and then PCM/EC. Select FUEL PUMP under fuel delivery and command fuel pump off. Engine will stall in 3-5 seconds. Turn ignition off.
2. Install Fuel Pressure Gauge (SA9127E) and 90-Degree Adapter (SA9403E) to fuel pressure test port. When installing fuel pressure gauge, wrap shop towel around pressure connection to absorb fuel leakage. Install gauge bleed hose in container. Open bleed valve to bleed fuel pressure.

FUEL SYSTEM PRESSURE TEST (EXCEPT AURORA & SATURN)

1. If diagnostic system check has already been performed, go to next step. If diagnostic system check has not been performed, go to DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS in appropriate SELF-DIAGNOSTICS article.
2. Turn ignition off. Turn A/C system off. On all models except 2.2L and 2.4L, connect Fuel Pressure Gauge (J-34730-1A) to fuel pressure fitting on fuel rail. On 2.2L and 2.4L, install Fuel Pressure Gauge (J-29658-D). This kit modifies fuel pressure gauge so it may be installed in fuel delivery line with quick-connect fittings. On all models, place fuel pressure gauge bleed hose into container. Turn ignition on. Bleed air out of fuel pressure gauge. Turn ignition off for 10 seconds. Turn ignition on. Fuel pump should run for about 2 seconds. Cycle ignition to obtain highest fuel pressure possible. Observe fuel pressure with fuel pump running. Fuel pressure should be within specification. See «FUEL PRESSURE SPECIFICATIONS (EXCEPT AURORA & SATURN)»(/buick/lesabre/viii-2000-2005/remont/testing-diagnostics/#engine-control-system-basic-diagnostic-procedures) table. If fuel pressure is within specification, go to next step. If fuel pressure is not within specification, go to step 12 .
3. Fuel pressure may vary slightly when fuel pump stops. After fuel pump stops, fuel pressure should stabilize and remain constant. Note fuel pressure when fuel pump stops running. If fuel pressure decreases more than 5 psi (0.3 kg/cm 2 ) in 10 minutes, go to step 10 . If fuel pressure does not decrease more than 5 psi (0.3 kg/cm 2 ) in 10 minutes, go to next step.
4. Relieve fuel pressure until pressure is 10 psi (0.7 kg/cm 2 ). If fuel pressure decreases more than 2 psi (0.1 kg/cm 2 ) in 10 minutes, go to step 19 . If fuel pressure does not decrease more than 2 psi (0.1 kg/cm 2 ) in 10 minutes, go to next step.
5. If fuel pressure is suspected of decreasing during acceleration, cruise or hard cornering, go to next step. If fuel pressure is not suspected of decreasing during acceleration, cruise or hard cornering, go to step 8 .
6. Inspect in-line fuel filter and fuel feed pipe for restriction. Repair as necessary. After repairs, go to step 24 . If no restriction is found, go to next step.
7. Remove fuel sending unit assembly. Inspect fuel pump strainer for restriction and correct installation. Check fuel pump flex pipe for leaks, and ensure fuel pump is correct for application. Repair as necessary. After repairs, go to step 24 . If no problem is found, go to step 19 .
8. Turn ignition off for 10 seconds. Turn ignition on. Fuel pump should run for about 2 seconds. Cycle ignition to obtain highest fuel pressure possible. Note fuel pressure. Start engine. Allow engine to idle until normal operating temperature is reached. If fuel pressure is less than previously noted pressure by 3-10 psi (0.2-0.7 kg/cm 2 ), check for intermittent problem. See appropriate TROUBLE SHOOTING - NO CODES article. If fuel pressure is greater than previously noted pressure by 3-10 psi (0.2-0.7 kg/cm 2 ), go to next step.
9. Disconnect vacuum hose from fuel pressure regulator. With engine idling, apply 12-14 in. Hg of vacuum to fuel pressure regulator. If fuel pressure decreases by 3-10 psi (0.2-0.7 kg/cm 2 ), go to step 20 . If fuel pressure does not decrease by 3-10 psi (0.2-0.7 kg/cm 2 ), go to step 21 .
10. Turn ignition off. Relieve fuel pressure. See «FUEL SYSTEM PRESSURE RELIEF (EXCEPT SATURN)»(/buick/lesabre/viii-2000-2005/remont/testing-diagnostics/#engine-control-system-basic-diagnostic-procedures__fuel-system-pressure-relief-except-saturn) . Disconnect fuel supply and return hoses at fuel rail. Install Fuel Pipe Shutoff Adapters (J-37287) between fuel hoses and fuel rail pipes. Open valve on fuel pipe shutoff adapters. Place bleed hose into container. Turn ignition on. Using scan tool, command fuel pump on. Bleed air out of fuel pressure gauge. Using scan tool, command fuel pump on and off. Close valve on fuel supply pipe shutoff adapter. Monitor fuel pressure for one minute. If fuel pressure remains constant, go to step 19 . If fuel pressure does not remain constant, go to next step.
11. Turn ignition off. Open valve on fuel supply pipe shutoff adapter. Turn ignition on. Using scan tool, command fuel pump on and off. Close valve on return pipe shutoff adapter. Monitor fuel pressure for one minute. If fuel pressure remains constant, go to step 21 . If fuel pressure does not remain constant, go to step 22 .
12. If fuel pressure is greater than specification, go to next step. See «FUEL PRESSURE SPECIFICATIONS (EXCEPT AURORA & SATURN)»(/buick/lesabre/viii-2000-2005/remont/testing-diagnostics/#engine-control-system-basic-diagnostic-procedures) table. If fuel pressure is less than specification, go to step 15 .
13. Relieve fuel pressure. See «FUEL SYSTEM PRESSURE RELIEF (EXCEPT SATURN)»(/buick/lesabre/viii-2000-2005/remont/testing-diagnostics/#engine-control-system-basic-diagnostic-procedures__fuel-system-pressure-relief-except-saturn) . Disconnect fuel return pipe from fuel rail. Attach flexible fuel hose to fuel rail return outlet passage. Place other end of flexible hose into container. Turn ignition off for about 10 seconds. Turn ignition on. Observe fuel pressure gauge with fuel pump running. Fuel pressure should be within specification. See «FUEL PRESSURE SPECIFICATIONS (EXCEPT AURORA & SATURN)»(/buick/lesabre/viii-2000-2005/remont/testing-diagnostics/#engine-control-system-basic-diagnostic-procedures) table. If fuel pressure is within specification, go to step 23 . If fuel pressure is not within specification, go to next step.
14. Inspect fuel rail outlet passage for restriction. Repair as necessary. After repairs, go to step 24 . If no restriction is found, go to step 21 .
15. If fuel pressure is greater than zero psi, go to next step. If fuel pressure is zero psi, go to step 17 .
16. Turn ignition off. Relieve fuel pressure. See «FUEL SYSTEM PRESSURE RELIEF (EXCEPT SATURN)»(/buick/lesabre/viii-2000-2005/remont/testing-diagnostics/#engine-control-system-basic-diagnostic-procedures__fuel-system-pressure-relief-except-saturn) . Disconnect fuel supply and return hoses at fuel rail. Install Fuel Pipe Shutoff Adapters (J-37287) between fuel hoses and fuel rail pipes. Open valve on fuel pipe shutoff adapters. Place bleed hose into container. Turn ignition on. Using scan tool, command fuel pump on. Bleed air out of fuel pressure gauge. DO NOT allow fuel pressure to exceed 65 psi. Excess pressure may damage fuel pressure regulator. Wait for fuel pressure to build. Slowly close valve on return pipe shutoff adapter. Using scan tool, command fuel pump on. If fuel pressure increases to greater than specification, go to step 21 . See «FUEL PRESSURE SPECIFICATIONS (EXCEPT AURORA & SATURN)»(/buick/lesabre/viii-2000-2005/remont/testing-diagnostics/#engine-control-system-basic-diagnostic-procedures) table. If fuel pressure does not increase to greater than specification, go to step 7 .
17. Check fuel pump electrical circuit. See appropriate diagnostic procedure under «NO-START DIAGNOSIS»(/buick/lesabre/viii-2000-2005/remont/testing-diagnostics/#engine-control-system-basic-diagnostic-procedures__no-start-diagnosis) . Repair as necessary. After repairs, go to step 24 . If no problem is found, go to next step.
18. Remove fuel sending unit assembly. Inspect in-line fuel filter, fuel feed pipe and fuel pump strainer for restrictions. Check fuel pump flex pipe for leaks. Repair as necessary. After repairs, go to step 24 . If no problem is found, go to next step.
19. Replace fuel sending unit assembly. After repairs, go to step 24 .
20. Locate and repair loss of vacuum to fuel pressure regulator. After repairs, go to step 24 .
21. Replace fuel pressure regulator. After repairs, go to step 24 .
22. Locate and replace leaking fuel injector(s). After repairs, go to step 24 .
23. Locate and repair restriction in fuel return pipe. After repairs, go to step 24 .
24. Turn ignition off. Turn A/C system off. On all models except 2.2L and 2.4L, connect Fuel Pressure Gauge (J-34730-1A) to fuel pressure fitting on fuel rail. On 2.2L and 2.4L, install Fuel Pressure Gauge (J-29658-D). This kit modifies fuel pressure gauge so it may be installed in fuel delivery line with quick-connect fittings. On all models, place fuel pressure gauge bleed hose into container. Turn ignition on. Bleed air out of fuel pressure gauge. Turn ignition off for 10 seconds. Turn ignition on. Fuel pump should run for about 2 seconds. Cycle ignition to obtain highest fuel pressure possible. Observe fuel pressure with fuel pump running. Fuel pressure should be within specification. See «FUEL PRESSURE SPECIFICATIONS (EXCEPT AURORA & SATURN)»(/buick/lesabre/viii-2000-2005/remont/testing-diagnostics/#engine-control-system-basic-diagnostic-procedures) table. If fuel pressure is within specification, go to next step. If fuel pressure is not within specification, go to step 11 .
25. Fuel pressure may vary slightly when fuel pump stops. After fuel pump stops, fuel pressure should stabilize and remain constant. Note fuel pressure when fuel pump stops running. If fuel pressure decreases more than 5 psi (0.3 kg/cm 2 ) in 10 minutes, go to step 10 . If fuel pressure does not decrease more than 5 psi (0.3 kg/cm 2 ) in 10 minutes, system is okay.

FUEL PRESSURE SPECIFICATIONS (EXCEPT AURORA & SATURN)

FUEL SYSTEM PRESSURE TEST (AURORA)

1. If diagnostic system check has already been performed, go to next step. If diagnostic system check has not been performed, go to DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS under DIAGNOSTIC SYSTEM CHECKS in appropriate SELF-DIAGNOSTICS article.
2. Ensure ignition is on. Using scan tool, command fuel pump on. If fuel pump operates, go to next step. If fuel pump does not operate, go to «FUEL PUMP ELECTRICAL CIRCUIT DIAGNOSIS»(/buick/lesabre/viii-2000-2005/remont/testing-diagnostics/#engine-control-system-basic-diagnostic-procedures__fuel-pump-electrical-circuit-diagnosis) under NO-START - ENGINE CRANKS OKAY (3.5L & 4.0L AURORA)
3. Turn ignition off. Ensure fuel tank has adequate fuel. Turn A/C system off. Connect Fuel Pressure Gauge (J-34730-1A) to fuel pressure fitting on fuel rail. Pace fuel pressure gauge bleed hose into container. Turn ignition on. Bleed air out of fuel pressure gauge. Turn ignition off for 10 seconds. Turn ignition on. Fuel pump should run for about 2 seconds. Cycle ignition several times to obtain highest fuel pressure possible. Observe fuel pressure with fuel pump running. Fuel pressure should be within specification. See «FUEL PRESSURE SPECIFICATIONS (AURORA)»(/buick/lesabre/viii-2000-2005/remont/testing-diagnostics/#engine-control-system-basic-diagnostic-procedures) table. If fuel pressure is as specified, go to next step. If fuel pressure is not as specified, go to step 12 . FUEL PRESSURE SPECIFICATIONS (AURORA) Application (1) psi (kg/cm 2 ) 3.5L & 4.0L 41-47 (2.9-3.3) (1) Specification listed is with ignition on and engine off.
4. Fuel pressure may vary slightly when fuel pump stops. After fuel pump stops, fuel pressure should stabilize and remain constant. Note fuel pressure when fuel pump stops running. If fuel pressure decreases more than 5 psi (0.4 kg/cm 2 ) in one minute, go to step 9 . If fuel pressure does not decrease more than 5 psi in one minute, go to next step.
5. Relieve fuel pressure until pressure is 10 psi (0.7 kg/cm 2 ). Monitor fuel pressure gauge for 5 minutes. If fuel pressure decreases more than 2 psi (0.1 kg/cm 2 ) in 5 minutes, go to step 24 . If fuel pressure does not decrease more than 2 psi (0.1 kg/cm 2 ) in 5 minutes, go to next step.
6. Turn ignition off for 15 seconds. Turn ignition on. Observe fuel pressure gauge. Start engine. If fuel pressure decreases 3-10 psi (0.2-0.7 kg/cm 2 ), go to next step. If fuel pressure does not decrease 3-10 psi (0.2-0.7 kg/cm 2 ), go to step 8 .
7. Operate vehicle within conditions of customers concern. If any scan tool parameters indicate a lean condition, go to step 17 . If no scan tool parameters indicate a lean condition, diagnose by symptom. See appropriate TROUBLE SHOOTING - NO CODES article.
8. Disconnect vacuum hose from fuel pressure regulator. With engine idling, apply 12-14 in. Hg of vacuum to fuel pressure regulator. If fuel pressure decreases by 3-10 psi (0.2-0.7 kg/cm 2 ), go to step 21 . If fuel pressure does not decrease 3-10 psi (0.2-0.7 kg/cm 2 ), go to step 23 .
9. Turn ignition off. Disconnect vacuum hose from fuel pressure regulator. Turn ignition on. Using scan tool, command fuel pump on. Check for fuel leak at pressure regulator vacuum port. If pressure regulator is leaking fuel, go to step 23 . If pressure regulator is not leaking fuel, go to next step.
10. Turn ignition off. Relieve fuel pressure. See «FUEL SYSTEM RELIEF (EXCEPT SATURN)»(/buick/lesabre/viii-2000-2005/remont/testing-diagnostics/#engine-control-system-basic-diagnostic-procedures) . Disconnect fuel supply and return hoses at fuel rail. Install Fuel Pipe Shutoff Adapters (J-37287) between fuel hoses and fuel rail pipes. Open valve on fuel pipe shutoff adapters. Place bleed hose into container. Turn ignition on. Using scan tool, command fuel pump on. Bleed air out of fuel pressure gauge. Using scan tool, command fuel pump on and off. Close valve on fuel supply pipe shutoff adapter. Monitor fuel pressure for one minute. If fuel pressure remains constant, go to step 19 . If fuel pressure does not remain constant, go to next step.
11. Turn ignition off. Open valve on fuel supply pipe shutoff adapter. Turn ignition on. Using scan tool, command fuel pump on and off. Close valve on return pipe shutoff adapter. Monitor fuel pressure for one minute. If fuel pressure remains constant, go to step 23 . If fuel pressure does not remain constant, go to step 20 .
12. If fuel pressure is more than 62 psi (4.4 kg/cm 2 ), go to step 14 . If fuel pressure is not more than 62 psi (4.4.7 kg/cm 2 ), go to next step.
13. If fuel pressure is more than zero psi, go to step 16 . If fuel pressure is zero psi, go to step 17 .
14. Turn ignition off. Relieve fuel pressure. See «FUEL SYSTEM PRESSURE RELIEF (EXCEPT SATURN)»(/buick/lesabre/viii-2000-2005/remont/testing-diagnostics/#engine-control-system-basic-diagnostic-procedures__fuel-system-pressure-relief-except-saturn) . Disconnect fuel return pipe from fuel rail. Attach a flexible fuel hose to fuel rail return outlet passage. Place other end of flexible hose into container. Turn ignition on. Observe fuel pressure gauge with fuel pump running. Fuel pressure should be within specification. See «FUEL PRESSURE SPECIFICATIONS (AURORA)»(/buick/lesabre/viii-2000-2005/remont/testing-diagnostics/#engine-control-system-basic-diagnostic-procedures) table. If fuel pressure is as specified, go to step 22 . If fuel pressure is not as specified, go to next step.
15. Inspect fuel rail outlet passage for restriction. Repair as necessary. After repairs, go to step 25 . If no restriction is found, go to step 23 .
16. Turn ignition off. Relieve fuel pressure. See «FUEL SYSTEM RELIEF (EXCEPT SATURN)»(/buick/lesabre/viii-2000-2005/remont/testing-diagnostics/#engine-control-system-basic-diagnostic-procedures) . Disconnect fuel supply and return hoses at fuel rail. Install Fuel Pipe Shutoff Adapters (J-37287) between fuel hoses and fuel rail pipes. Open valve on fuel pipe shutoff adapters. Place bleed hose into container. Turn ignition on. Using scan tool, command fuel pump on. Bleed air out of fuel pressure gauge. DO NOT allow fuel pressure to exceed 75 psi (5.3 kg/cm 2 ). Excess pressure may damage fuel pressure regulator. Wait for fuel pressure to build. Slowly close valve on return pipe shutoff adapter. Using scan tool, command fuel pump on. If fuel pressure increases to more than 47 psi (3.3 kg/cm 2 ), go to step 23 . If fuel pressure does not increase to more than 47 psi (3.3 kg/cm 2 ), go to next step.
17. Inspect fuel filter and fuel supply pipe for restrictions. Repair as necessary. After repairs, go to step 25 . If no problems are found, go to next step.
18. Inspect fuel pump connectors and ground circuit for poor connections. Repair as necessary. After repairs, go to step 25 . If no problems are found, go to next step
19. Remove fuel pump assembly. Fuel pump can be accessed through an inspection panel in trunk. Inspect fuel pump strainer for restrictions. Check fuel pump flex pipe for leaks. Check for contaminates in fuel tank. Repair as necessary. After repairs, go to step 25 . If no problems are found, go to step 24 .
20. Locate and replace leaking fuel injector(s). After repairs, go to step 25 .
21. Locate and repair loss of vacuum to fuel pressure regulator. After repairs, go to step 25 .
22. Locate and repair restriction in fuel return pipe. After repairs, go to step 25 .
23. Replace fuel pressure regulator. After repairs, go to step 25 .
24. Replace fuel pump. After repairs, go to next step.
25. Turn ignition off. Reconnect all disconnected connectors. Turn ignition on. Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Start engine. If engine starts and continues to idle, system is okay. If engine does not start or continue to idle, go to step 3 .

FUEL SYSTEM PRESSURE TEST (SATURN)

Note. Ensure battery is fully charged when performing test.

1. Remove air induction tube. Relieve fuel pressure. See «FUEL SYSTEM PRESSURE RELIEF (SATURN)»(/buick/lesabre/viii-2000-2005/remont/testing-diagnostics/#engine-control-system-basic-diagnostic-procedures__fuel-system-pressure-relief-saturn) . Install fuel pressure gauge and bleed off any fuel in system into container. Close fuel pressure gauge shutoff valve.
2. Turn ignition on. Using scan tool, command fuel pump on for at least 10 seconds. Allow pressure to stabilize. Record maximum fuel pressure. Ensure fuel pressure is as specified. See «FUEL PRESSURE SPECIFICATIONS (SATURN)»(/buick/lesabre/viii-2000-2005/remont/testing-diagnostics/#engine-control-system-basic-diagnostic-procedures) table.
3. Bleed fuel pressure and repeat test at least 2 more times. If during test, fuel pressure drops more than 8 psi (0.6 kg/cm 2 ) during a 5 minute period, isolate fuel supply side of fuel system by closing off return side with fuel pressure gauge shutoff valve.
4. Using scan tool, command fuel pump on. Allow fuel pressure to stabilize. Record maximum fuel pressure. If fuel pressure remains stable, replace fuel pressure regulator. If fuel pressure bleeds off more than 8 psi (0.6 kg/cm 2 ), check fuel inlet line and injectors for leaks, and check for faulty fuel pump. Repair as necessary.

FUEL PRESSURE SPECIFICATIONS (SATURN)

BASIC IGNITION SYSTEM CHECKS

Note. For circuit identification, see WIRING DIAGRAMS article.

Spark

1. If factory tachometer is connected to coil tachometer terminal, disconnect tachometer before performing tests. When removing spark plug wire from spark plug, twist and pull on boot. DO NOT pull on wire.
2. Using Spark Tester (J-26792), check for spark at each spark plug wire. Leave other wires connected while checking for spark. Check spark plug wire resistance on suspect wires. See IGNITION SYSTEMS in appropriate SERVICE & ADJUSTMENT SPECIFICATIONS article.

Ignition Coil Power Source

Turn ignition on. Check ignition positive voltage circuit at ignition control module for battery voltage. If battery voltage is not present, check ignition or PCM fuse. If fuse is okay, check for open in circuit between fuse and ignition control module.

Ignition Coil Resistance (Except 1.9L)

If ignition coil is suspected of causing a misfire or no-spark condition, switch coil locations on ignition control module. If problem follows questionable coil, check ignition coil resistance or replace original coil. For ignition coil resistance, see IGNITION COIL RESISTANCE table.

IGNITION COIL RESISTANCE

Ignition Coil Resistance (1.9L)

1. Disconnect ignition coil leads. Measure secondary coil resistance (secondary tower-to-secondary tower). Resistance should be 6500-11,500 ohms. If resistance is not within specification, replace ignition coil.
2. Ignition coil primary resistance value is not available from manufacturer. If ignition coil is suspected of causing a misfire or a no-spark condition, switch coil locations on EI module. If problem follows questionable coil, replace original coil.

Ignition Relay Circuit (5.7L - "F" Body)

1. If diagnostic system check has already been performed, go to next step. If diagnostic system check has not been performed, go to DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS in appropriate SELF-DIAGNOSTICS article.
2. Turn ignition off. Remove IGN relay from underhood electrical center. Using test light connected to ground, probe battery feed circuit at IGN relay cavity. If test light illuminates, go to next step. If test light does not illuminate, go to step 8 .
3. Turn ignition on. Using test light connected to ground, probe ignition feed circuit at IGN relay cavity. If test light illuminates, go to next step. If test light does not illuminate, go to step 9 .
4. Turn ignition off. Measure resistance between chassis ground and ground circuit at IGN relay cavity. If resistance is less than 2 ohms, go to next step. If resistance is not less than 2 ohms, go to step 10 .
5. Turn ignition off. Connect fused jumper wire between IGN relay battery feed circuit and IGN relay load circuit at relay cavities. Using test light connected to ground, probe terminals of the following fuses located in underhood electrical center No. 2: A/C CRUISE ENG CTRL ENG SEN INJR1 INJR2 If test light illuminates for all fuses, go to next step. If test light does not illuminate, go to step 11 .
6. Check for poor terminal connection at IGN relay. Repair as necessary. If connections are okay, go to next step.
7. Replace IGN relay.
8. Repair open in IGN relay battery feed circuit.
9. Repair IGN relay ignition feed circuit.
10. Repair open or high resistance in IGN relay ground circuit.
11. Repair IGN relay load circuit.

Ignition Relay Circuit (5.7L - "Y" Body)

1. If diagnostic system check has already been performed, go to next step. If diagnostic system check has not been performed, go to DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS in appropriate SELF-DIAGNOSTICS article.
2. Turn ignition off. Remove IGN relay from underhood electrical center. Using test light connected to ground, probe battery feed circuit at IGN relay cavity. If test light illuminates, go to next step. If test light does not illuminate, go to step 8 .
3. Turn ignition on. Using test light connected to ground, probe ignition feed circuit at IGN relay cavity. If test light illuminates, go to next step. If test light does not illuminate, go to step 9 .
4. Using test light connected to battery voltage, probe IGN relay ground circuit at relay cavity. If test light illuminates, go to next step. If test light does not illuminate, go to step 10 .
5. Turn ignition off. Connect fused jumper wire between IGN relay battery feed circuit and IGN relay load circuit at relay cavities. Using test light connected to ground, probe terminals of the following fuses located in underhood electrical center: A/C ENG IGN1 INJR1 INJR2 THROT CONT If test light illuminates for all fuses, go to next step. If test light does not illuminate, go to step 11 .
6. Check for poor IGN relay connections. If poor connections are found, go to step 11 . If connections are okay, go to next step.
7. Replace IGN relay.
8. Repair open in IGN relay battery feed circuit.
9. Repair IGN relay ignition feed circuit.
10. Repair open in IGN relay ground circuit.
11. Replace underhood electrical center.

Crankshaft Position (CKP) Sensor Output Signal

Set DVOM on 2-volt AC scale. Connect DVOM leads to CKP sensor located on side of engine block. Crank engine and observe voltmeter reading. CKP sensor should generate a voltage signal of about 2 volts.

Tach Pulse (RPM) Signal

Connect scan tool to DLC. RPM should be indicated on scan tool when engine is cranked or running. Tach pulse (RPM reference) will be indicated as a voltage signal when a DVOM (with a minimum 10-megohm input impedance connected to ground) is used to backprobe RPM high reference circuit. If tach pulse signal is not present, engine will not run.

1. Disconnect tachometer wire from IDI module (if equipped). A shorted tachometer will not allow engine to start. Temporarily remove IDI assembly and install Spark Plug Jumper Wires (J-36012).
2. Using Spark Tester (J-26792), check for spark at each spark plug wire. Leave other wires connected while checking for spark.

Turn ignition on. Check battery feed circuit at ignition control module for battery voltage. If battery voltage is not present, check ignition fuse. If fuse is not blown, check for open in circuit between fuse and ignition control module.

Ignition Coil Resistance

1. Disconnect ignition coil leads. Measure secondary coil resistance (secondary tower-to-secondary tower). Resistance should be 4000-8000 ohms. If resistance is not within specification, replace ignition coil.
2. Ignition coil primary resistance value is not available from manufacturer. If ignition coil is suspected of causing a misfire or a no-spark condition, switch coil locations on ignition control module. If problem follows questionable coil, replace original coil.

Crankshaft Position (CKP) Sensor Short & Resistance Checks

1. Set DVOM on 2000-ohm scale. Connect DVOM leads to CKP sensor connector located on side of engine block. Turn ignition off. Disconnect ignition control module harness connectors. Measure resistance between CKP sensor terminals at ignition control module connector.
2. CKP sensor resistance should be 500-900 ohms. If resistance is not as specified, replace CKP sensor. If sensor resistance is within specification, go to next step.
3. With CKP sensor installed in block, connect one DVOM lead to either sensor terminal at ignition control module. Touch other lead of DVOM to engine block. Continuity should not exist. If continuity exists, CKP sensor or circuit is shorted to ground and must be repaired or replaced.

Set DVOM on 2-volt AC scale. Connect DVOM leads to CKP sensor located on side of engine block. Crank engine and observe voltmeter reading. CKP sensor should generate a voltage signal of about 1100-1300 millivolts as crankshaft turns. Ignition control module can be triggered with a voltage signal as low as 200 millivolts.

Connect scan tool to DLC. RPM should be indicated on scan tool when engine is cranked or running. Tach pulse (RPM reference) will be indicated as a voltage signal when a DVOM (with a minimum 10-megohm input impedance connected to ground) is used to backprobe RPM high reference circuit. If tach pulse signal is not present, engine will not run.

Disconnect tachometer wire (if equipped). A shorted tachometer will prevent engine from starting. Disconnect Camshaft Position (CMP) sensor. Attempt to start engine. If engine starts, see appropriate CMP sensor DTC test in appropriate SELF-DIAGNOSTICS article. Using Spark Tester (J-26792), check for adequate spark. Check for spark on plug wires No. 1, 3 and 5 (one at a time). Leave companion cylinder plug wire connected while checking for spark. When removing spark plug wire from spark plug, twist and pull on boot. DO NOT pull on wire.

Turn ignition on. Check for battery voltage on ignition positive voltage circuit at ignition control module. If battery voltage is not present, check for blown ignition fuse. If fuse is okay, check for open in circuit between fuse and ignition control module.

Disconnect ignition coil leads. Using DVOM, measure ignition coil resistance. Secondary resistance should be 5000-8000 ohms. If resistance is not as specified, replace ignition coil.

Connect scan tool to DLC. RPM should be indicated on scan tool when engine is cranked or running. Tach pulse (RPM reference) will be indicated as a voltage signal when a DVOM (with a minimum 10-megohm input impedance connected to ground) is used to backprobe RPM high reference circuit. If tach pulse signal is not present, engine will not run.

IDLE SPEED & IGNITION TIMING

Ensure idle speed and ignition timing are set to specification. For specifications and adjustments, see appropriate SERVICE & ADJUSTMENT SPECIFICATIONS and ON-VEHICLE ADJUSTMENTS articles.

SUMMARY

If no faults were found while performing basic diagnostic procedures, or no trouble codes (or only intermittent ones) were found while performing diagnostic system check, and driveability problems still exist, proceed to appropriate TROUBLE SHOOTING - NO CODES article for diagnosis by symptom (i.e., ROUGH IDLE, NO-START, etc.) or intermittent diagnostic procedures.

See also:
• NO RPM DETECTED DIAGNOSIS
• IGNITION DIAGNOSIS
• FUEL DELIVERY DIAGNOSIS
• BASIC FUEL SYSTEM CHECKS
• BASIC IGNITION SYSTEM CHECKS
• FUEL PUMP ELECTRICAL CIRCUIT
• FUEL SYSTEM DIAGNOSIS
• NO RPM DETECTED DIAGNOSIS
• FUEL DELIVERY SYSTEM
• FUEL INJECTOR CIRCUIT DIAGNOSIS (3.1L & 3.4L)
• FUEL PUMP ELECTRICAL CIRCUIT DIAGNOSIS (3.1L CENTURY & GRAND PRIX; 3.4L IMPALA & MONTE CARLO)
• FUEL SYSTEM DIAGNOSIS (3.1L & 3.4L)
• IGNITION SYSTEM DIAGNOSIS (3.1L & 3.4L)
• IGNITION RELAY DIAGNOSIS (3.1L GRAND PRIX; 3.4L IMPALA & MONTE CARLO ONLY)
• FUEL PUMP ELECTRICAL CIRCUIT DIAGNOSIS
• DIAGNOSTIC AIDS
• IGNITION RELAY DIAGNOSIS
• IGNITION RELAY DIAGNOSIS
• IGNITION SYSTEM DIAGNOSIS (ALL MODELS)
• FUEL PUMP ELECTRICAL CIRCUIT (EXCEPT VIN K - GRAND PRIX)
• FUEL SYSTEM DIAGNOSIS (ALL MODELS)
• FUEL INJECTOR CIRCUIT (VIN K - CAMARO, FIREBIRD, IMPALA & MONTE CARLO)
• FUEL PUMP ELECTRICAL CIRCUIT (VIN K - GRAND PRIX)
• FUEL INJECTOR CIRCUIT DIAGNOSIS (VIN K & 1 - BONNEVILLE, GRAND PRIX, LESABRE & PARK AVENUE)
• IGNITION RELAY CIRCUIT (5.7L)
• FUEL PUMP ELECTRICAL CIRCUIT ("F" BODY)
• FUEL PUMP ELECTRICAL CIRCUIT ("Y" BODY)
• NO-START DIAGNOSIS
• FUEL SYSTEM PRESSURE RELIEF (EXCEPT SATURN)
• FUEL SYSTEM PRESSURE RELIEF (SATURN)