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Warning Light Circuit Diagnosis (3.4L)

  1. Perform powertrain diagnostic system check. See POWERTRAIN DIAGNOSTIC SYSTEM CHECK in appropriate SELF-DIAGNOSTICS article. After performing powertrain diagnostic system check, go to next step.
  2. Diagnose instrument cluster. See appropriate INSTRUMENT PANELS article in ACCESSORIES & EQUIPMENT. After diagnosis, go to next step.
  3. Turn ignition off. Disconnect PCM harness connectors. Turn ignition on. Using DVOM, measure voltage between ground and affected PCM output circuit at PCM harness connector. See 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 ground and affected PCM output circuit at PCM harness connector. See WIRING DIAGRAMS article. Monitor current reading for about 2 minutes. If current is.05-1.5 amps, go to step  12. If current is not.05-1.5 amps, go to next step.
  5. Disconnect instrument cluster connector. Leave PCM harness connectors disconnected. Using DVOM, measure voltage between ground and affected PCM output circuit at instrument cluster connector. See WIRING DIAGRAMS article. If voltage is zero volts, go to step  15. If voltage is not zero volts, 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 and go to step  17.
  9. Disconnect instrument cluster connector. Turn ignition on. Using DVOM, measure voltage between ground and ignition feed circuit at instrument cluster connector. See WIRING DIAGRAMS article. 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 at 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 connector. Disconnect instrument cluster connector. Turn ignition on. Connect a test light between affected PCM output circuit and ignition feed circuit at instrument cluster connector. See WIRING DIAGRAMS article. Using scan tool, select OUTPUTS TEST, and 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 at 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. Replace instrument cluster. After repairs, go to step  17.
  16. Replace PCM and reprogram. Perform VTD password relearn procedure and perform crankshaft variation learn procedure. See COMPUTER RELEARN PROCEDURES in GENERAL INFORMATION article. 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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