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Engine Control System - Basic Diagnostic Procedures: Other Pontiac Bonneville X

Testing & Diagnostics ~8173 words

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.

WARNINGBecause fuel injectors on many models are triggered by ignition switch during cranking mode, DO NOT use ignition switch during compression tests. Use a remote starter to crank engine to prevent fire hazard or engine oiling system contamination.

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.

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.

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.

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 .

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.

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.

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.

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.

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.

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 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 .

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. 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.

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

CAUTIONBegin fuel system trouble shooting and diagnosis with checking fuel injection system pressure. High fuel pressure may be present in fuel lines and component parts. Relieve fuel pressure before disconnecting any fuel system components.

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.

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.

ApplicationOhms
Primary(1)
Secondary
2.2, 3.1L & 3.4L5000-8000
3.0L, 3.5L, 4.6L & 5.7L(1)
(1) Information is not available from manufacturer.
(1)Information is not available from manufacturer.

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.

More articles — Engine Control System - Basic Diagnostic Procedures