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HOMESERVICE MANUALSBUICK1999REGAL LSREPAIR AND DIAGNOSIS (SINGLE PAGE)ENGINE PERFORMANCESYSTEMENGINE CONTROL SYSTEM - BASIC ENGINE TESTINGNO START DIAGNOSISNO START - ENGINE CRANKS OKAY (2.4L)IGNITION SYSTEM
1999 Buick Regal LS

Ignition System

1999 Buick Regal LSSECTION Ignition System
  1. Perform On-Board Diagnostic (OBD) system check. See ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK in appropriate SELF-DIAGNOSTICS article. After performing OBD system check, go to next step.
  2. Check for Diagnostic Trouble Codes (DTCs). If DTC P0601, P0602 or P1629 is present, diagnose DTCs first. See appropriate SELF-DIAGNOSTICS article. If DTCs are not present, go to next step.
  3. Check PCM ground connection at engine block. If ground connection is okay, go to next step. If ground connection is faulty, go to step  5 .
  4. Check fuel pump, injector and ignition fuses, located in underhood fuse block. If fuses are okay, go to step  6 . If fuses are faulty, go to step  7 .
  5. Repair PCM ground connection. After repairs, go to step  37 .
  6. Check fuel level in tank and add if necessary. If fuel level is okay, go to step  8 . If fuel level was low and needed to be added, go to step  37 .
  7. Check for short to ground in fuel pump and injector ignition feed circuits. See appropriate wiring diagram in WIRING DIAGRAMS article. Repair as necessary. Replace faulty fuse(s). After repairs, go to step  37 .
  8. Install scan tool. Turn ignition on with engine off. Ensure throttle is closed. Observe TP sensor voltage. If TP sensor voltage is less than one volt, go to next step. If TP sensor voltage is not less than one volt, go to DTC P0123. See appropriate SELF-DIAGNOSTICS article.
  9. Using scan tool, monitor Engine Coolant Temperature (ECT) sensor and Intake Air Temperature (IAT) sensor values. Both values should be about the same. If values are the same, go to next step. If values are not the same, go to DTC P0117 or P0118. See appropriate SELF-DIAGNOSTICS article.
  10. Using scan tool, observe MAP sensor voltage while cranking engine. If serial data is lost while cranking engine, go to step  13 . If serial date is not lost while cranking engine, go to next step.
  11. Check MAP sensor value with ignition on and engine cranking. If MAP sensor voltage is greater than 4 volts, and then changes while cranking engine, go to next step. If MAP sensor voltage is not greater than 4 volts, or does not change while cranking engine, diagnose MAP sensor. See appropriate SYSTEM & COMPONENT TESTING article.
  12. Using scan tool, check Crankshaft Position (CKP) sensor activity while cranking engine. If CKP ACTIVITY COUNTER increments while cranking, go to step  28 . If CKP ACTIVITY COUNTER does not increment, go to step  14 .
  13. Repair voltage loss to PCM from ignition switch. After repairs, go to step  37 .
  14. Turn ignition off. Disconnect 11-pin Ignition Control Module (ICM) harness connector. Turn ignition on with engine off. Connect DVOM between ICM ground and ignition feed terminals. See appropriate wiring diagram in WIRING DIAGRAMS article. If battery voltage is present, go to next step. If battery voltage is not present, go to step  16 .
  15. Connect DVOM between ICM connector CKP sensor ground terminal and CKP sensor signal terminal. See appropriate wiring diagram in WIRING DIAGRAMS article. Measure combined CKP sensor and harness resistance. Resistance should be 500-900 ohms. If resistance is as specified, go to step  19 . If resistance is not as specified, go to step  18 .
  16. Repair open in ground circuit or ignition feed circuit to ICM. After repairs, go to step  37 .
  17. Check CKP sensor signal circuit for a short to ground. If CKP sensor signal circuit is okay, go to step  23 . If CKP sensor signal circuit is not okay, repair as necessary and go to step  37 .
  18. Turn ignition off. Remove CKP sensor. Using DVOM, measure CKP sensor resistance. Resistance should be 500-900 ohms. If resistance is as specified, go to step  22 . If resistance is not as specified, go to step  23 .
  19. Set DVOM to AC scale. Connect DVOM between ICM harness connector CKP sensor ground terminal and CKP sensor signal terminal. See appropriate wiring diagram in WIRING DIAGRAMS article. Crank engine. If voltage reading is greater than 200 millivolts, go to next step. If voltage reading is not as specified, go to step  17 .
  20. Check for a short to power in CKP sensor signal circuit. If CKP sensor signal circuit is okay, go to next step. If CKP sensor signal circuit is not okay, repair as necessary and go to step  37 .
  21. Using a test light connected to ICM harness connector 7X reference signal terminal, touch battery negative terminal, and then battery positive terminal. See appropriate wiring diagram in WIRING DIAGRAMS article. Monitor CKP ACTIVITY COUNTER on scan tool. If CKP ACTIVITY COUNTER increments as test light is touched to battery positive, go to step  24 . If CKP ACTIVITY COUNTER does not increment, go to step  25 .
  22. Repair poor connection, open or short in CKP sensor. After repairs, go to step  37 .
  23. Replace CKP sensor. After replacing CKP sensor, go to step  37 .
  24. Inspect ICM harness connector. Check for clean and tight connections. Repair as necessary. After repairs, go to step  37 . If connector is okay, go to step  26 .
  25. Check CKP activity (7X reference) circuit for an open or short. Repair as necessary. After repairs, go to step  37 . If circuit is okay, go to step  27 .
  26. Replace ICM. After replacing ICM, go to step  37 .
  27. Turn ignition off. Check for poor connection at PCM. Repair as necessary. If connection is okay, replace PCM. Perform PCM relearn procedures. After replacing PCM, go to step  37 .
  28. Disconnect all fuel injector harness connectors. Install injector test light on injector No. 1 harness connector. Crank engine and observe injector test light. If test light flashes, go to next step. If test light does not flash, go to step FUEL SYSTEM ELECTRICAL CIRCUIT  .
  29. Remove ignition coil and ignition control module assembly. Install Spark Plug Jumper (J-36012-A) between coil and ignition control module. Remove spark plug boot from companion cylinder of ignition coil housing and install jumper wire from spark plug boot connector of ignition housing to ground (cylinders No. 1-4 and 2-3). Using Spark Tester (J-26792), check for spark on all 4 wires (one at a time). If spark jumps spark tester on all 4 wires, go to next step. If spark does not jump on all 4 wires, go to step  32 .
    30. NOTE: Ignition switch may have to be cycled a few times to achieve the highest pressure reading.
  30. Install fuel pressure gauge. Turn ignition on with engine off. If engine is equipped with an EGR valve, fuel pressure should be 41-47 psi (2.9-3.3 kg/cm2 ). If engine is not equipped with an EGR valve, fuel pressure should be 52-58 psi (3.7-4.1 kg/cm2 ). If fuel pressure is as specified, go to next step. If fuel pressure is not as specified, go to BASIC FUEL SYSTEM CHECKS  .
  31. Check for fouled spark plugs. Replace as necessary. If spark plugs were fouled, go to step  37 . If spark plugs were okay, check for water in fuel system. Check for basic engine problem (low compression). Ensure spark plugs are of resistor type. Check fuel pump operation with scan tool.
    32. CAUTION: DO NOT leave test light connected to PCM harness connector ignition control circuit for more than 5 seconds at a time as ignition coil and/or Ignition Control Module (ICM) may be damaged.
  32. Turn ignition off. Disconnect Powertrain Control Module (PCM) harness connectors. Turn ignition on. Using a test light connected to battery positive, momentarily touch affected ignition control circuit with test light. A spark should jump across spark tester. If a spark jumps across tester, go to step  27 . If a spark does not jump across tester, go to next step.
  33. Turn ignition off. Disconnect spark plug jumper wires and remove ignition coil housing. Reconnect PCM harness connectors. Disconnect ignition coil harness connector at ICM. Connect an additional test light between battery positive and ICM control terminal for ignition coil(s) that did not spark. Crank engine and observe test light. If test light flashes, go to next step. If test light does not flash, go to step  36 .
  34. Check for faulty ignition coil harness connector or open in ignition coil. Repair as necessary. After repairs, go to step  37 . If ignition coils and harness connectors are okay, go to next step.
  35. Replace ignition coil that did not produce a spark. After repairs, go to step  37 .
  36. Check for an open or short in ignition control circuit. Repair as necessary. After repairs, go to next step. If circuit is okay, go to step  24 .
  37. Reconnect all components. 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 .
  38. Allow engine to reach normal operating temperature. Check for DTCs. If DTCs are present, diagnose DTCs. See appropriate SELF-DIAGNOSTICS article. If DTCs are not present, system is okay.
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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • • You smell fuel, burning insulation, or see smoke.
  • • Brakes feel soft, pull hard to one side, or make grinding noises.
  • • The engine overheats, stalls repeatedly, or misfires under load.
  • • You are missing required tools, torque specs, or safe lifting equipment.
  • • You are not confident in the next step or safety outcome.