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Home >> Oldsmobile >> 1998 >> Regency >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - System/Component Tests >> Miscellaneous Controls >> Pcm Controlled Warning Lights >> Warning Light Diagnosis
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Warning Light Diagnosis

  1. If powertrain OBD system check has been performed, go to next step. If powertrain OBD system check has not been performed, perform powertrain OBD system check. See POWERTRAIN OBD SYSTEM CHECK in TESTS W/CODES article.
  2. Check instrument cluster. See INSTRUMENT PANEL article in ACCESSORIES/SAFETY EQUIPMENT in section. If instrument panel is okay, go to next step.
  3. Turn ignition switch to LOCK position. Disconnect PCM connector. Turn ignition switch to RUN position. Measure voltage between affected PCM output circuit at PCM harness connector and ground. See diagram in WIRING DIAGRAMS article. If battery voltage does not exist, go to step 7). If battery voltage exists, go to next step.
  4. Set DVOM to 10-amp scale. Check current between affected PCM output circuit and ground. Monitor reading for about 2 minutes. DVOM should read .05-1.50 amps. If reading is as specified, go to step 12). If reading is not as specified, go to next step.
  5. Turn ignition switch to LOCK position. Disconnect instrument cluster harness connectors, but leave PCM connector disconnected. Measure voltage between affected PCM output circuit and ground. If zero volts exists, go to step 15). If voltage exists, go to next step.
  6. Locate and repair short to voltage in affected PCM output circuit. After repairs are complete, go to step 17).
  7. Check ignition feed fuse for instrument panel 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 panel cluster indicator lights. Replace fuse and go to step 17).
  9. Disconnect instrument cluster connectors. Turn ignition switch to RUN position. Measure voltage between ignition feed circuit for instrument panel cluster indicator lights and ground. If battery exists, go to next step. If battery voltage does not exist, go to step 14).
  10. Check affected PCM output circuit for an open or short to ground. If open or short exists, repair as necessary and go to step 17). If open or short does not exist, go to next step.
  11. Check affected PCM output circuit and ignition feed circuit for poor connection at instrument panel 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 switch to LOCK position. Connect PCM harness connectors. Disconnect instrument cluster connectors. Turn ignition switch to RUN position. Connect a test light between affected PCM output circuit and ignition feed circuit at instrument panel harness connector. Using a 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 panel cluster indicator lights. After repairs are complete, go to step 17).
  15. Repair or replace instrument cluster as necessary. After repairs, go to step 17).
  16. Replace PCM and go to next step.
  17. Using scan tool, operate affected warning light. If warning light does not operate properly, go to step 3).
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