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3.1L, 3.5L & 3.8L

  1. Check instrument cluster. See appropriate INSTRUMENT PANELS article in ACCESSORIES & EQUIPMENT. If instrument cluster is okay, go to next step.
  2. 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.
  3. Turn ignition off. Disconnect PCM harness connectors. Turn ignition on. Using DVOM, measure voltage between ground and tachometer control circuit (White wire) at PCM harness connector. 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 tachometer control circuit (White wire) at PCM harness connector. Monitor reading for about 2 minutes. If reading is less than 0.5 amp, go to step  12. If reading is not less than 0.5 amp, go to next step.
  5. Disconnect instrument cluster harness connectors. Leave PCM harness connectors disconnected. Using DVOM, measure voltage between ground and tachometer control circuit (White wire) at PCM harness connector. 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 tachometer control circuit (White wire) between instrument cluster and PCM. After repairs, go to step  17.
  7. Check ignition feed fuse for instrument cluster. 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 (Pink wire) to instrument cluster or a shorted component. Replace fuse. After repairs, go to step  17.
  9. Disconnect instrument cluster connectors. Turn ignition on. Using DVOM, measure voltage between ground and ignition feed circuit (Pink wire) at instrument cluster harness connector. If battery voltage exists, go to next step. If battery voltage does not exist, go to step  14.
  10. Check for open or short to ground in tachometer control circuit (White wire) between instrument cluster and PCM. If problem exists, repair as necessary and go to step  17. If problem does not exist, go to next step.
  11. Check tachometer control 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. Check for poor connections at PCM. If problem does not exist, go to step  16. If problem exists, repair as necessary and go to step  17.
  13. Check tachometer control 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. After repairs, go to step  17.
  15. Repair or replace instrument cluster. After repairs, go to step  17.
  16. Replace PCM. After repairs, go to next step.
  17. Start engine. Observe tachometer. If tachometer is operating properly, system is okay. If tachometer is not operating properly, repair instrument cluster as necessary. See appropriate INSTRUMENT PANELS article in ACCESSORIES & EQUIPMENT.
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