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HOMESERVICE MANUALSBUICK1999REGAL LSREPAIR AND DIAGNOSISENGINE PERFORMANCETESTING & DIAGNOSISENGINE CONTROL SYSTEM - SYSTEM TESTING & ENGINE COMPONENT TESTSMISCELLANEOUS CONTROLSPCM CONTROLLED WARNING LIGHTS3.4L & 3.8L
1999 Buick Regal LS

3.4L & 3.8L

1999 Buick Regal LSSECTION 3.4L & 3.8L
  1. If On-Board Diagnostic (OBD) system check has been performed, go to next step. If On-Board Diagnostic (OBD) system check has not been performed, perform On-Board Diagnostic (OBD) system check. See ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK in appropriate SELF-DIAGNOSTICS article.
  2. Check instrument cluster. See appropriate INSTRUMENT PANELS - ELECTRONIC article in ACCESSORIES & EQUIPMENT. If instrument panel is okay, go to next step.
  3. Turn ignition off. Disconnect PCM harness connectors. Turn ignition on. Using DVOM, measure voltage between affected PCM output circuit and ground. See appropriate wiring diagram in WIRING DIAGRAMS article. If battery voltage exists, go to next step. If battery voltage does not exist, go to step  7.
  4. Set DVOM to 10-amp scale. Using DVOM, measure current between affected PCM output circuit and ground. See appropriate wiring diagram in WIRING DIAGRAMS article. Monitor reading for about 2 minutes. If current reading remains .05-1.5 amps, go to step  12. If current reading does not remain .05-1.5 amps, go to next step.
  5. Turn ignition off. Disconnect instrument cluster harness connectors. Leave PCM connectors disconnected. Using DVOM, measure voltage between affected PCM output circuit and ground. See appropriate wiring diagram in WIRING DIAGRAMS article. If voltage is zero volts, go to step  15. If voltage is present, go to next step.
  6. Locate and repair short to voltage in affected PCM output circuit. After repairs, go to step  17.
  7. Check ignition feed fuse for instrument cluster indicator lights. If fuse is blown, go to next step. If fuse is okay, go to step  9.
  8. Locate and repair short to ground in ignition feed circuit for instrument cluster indicator lights. Replace fuse. After repairs, go to step  17.
  9. Disconnect instrument cluster connectors. Turn ignition on. Using DVOM, measure voltage between ignition feed circuit for instrument cluster indicator lights and ground. If battery voltage exists, go to next step. If battery voltage does not exist, go to step  14.
  10. Check for an open or short to ground in affected PCM output circuit. If problem exists, repair as necessary and go to step  17. If problem does not exist, go to next step.
  11. Check affected PCM output circuit and ignition feed circuit for poor connection at instrument cluster and PCM. If problem exists, repair as necessary and go to step  17. If problem does not exist, go to step  15.
  12. Turn ignition off. Reconnect PCM harness connectors. Disconnect instrument cluster connectors. Turn ignition on. Connect a test light between affected PCM output circuit and ignition feed circuit at instrument cluster harness connector. Using scan tool, perform OUTPUT TESTS function to cycle affected warning light on and off. If test light flashes on and off, check for shorted component or circuit in the output driver circuit. Check for faulty instrument cluster. If test light does not flash on and off, go to next step.
  13. Check affected PCM output circuit for poor connection to PCM. If problem exists, repair as necessary and go to step  17. If problem does not exist, go to step  16.
  14. Locate and repair open in ignition feed circuit to instrument cluster indicator lights. After repairs, go to step  17.
  15. Repair or replace instrument cluster as necessary. After repairs, go to step  17.
  16. Replace PCM. After repairs, go to next step.
  17. Using scan tool, operate affected warning light. If warning light operates properly, system is okay. If warning light does not operate properly, go to step  2.
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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.