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Tachometer Inaccurate/Inoperative

  1. If instrument cluster diagnostic system check was performed, go to next step. If instrument cluster diagnostic system check was not performed, go to INSTRUMENT CLUSTER DIAGNOSTIC SYSTEM CHECK  under SELF-DIAGNOSTIC SYSTEM.
  2. Turn ignition off. Connect scan tool to Data Link Connector (DLC). See Figure . Start engine and test drive vehicle. Using scan tool, select Powertrain Control Module (PCM) data display. Monitor ENGINE SPEED status. If ENGINE SPEED does not match tachometer reading, go to next step. If ENGINE SPEED matches tachometer reading, go to step  5 .
  3. Check for open, short to ground, short to voltage or high resistance in White or White/Black wire between PCM connector C2 terminal No. 56 and Instrument Panel Cluster (IPC) connector C2 terminal A4. See Figure and Figure . If circuit is okay, go to next step. If faulty circuit is found and repaired, go to step  8 .
  4. Check for poor connections at Instrument Panel Cluster (IPC) connector. If connections are okay, go to step  6 . If faulty connections are found and repaired, go to step  8 .
  5. Check for poor connections at PCM connector. If connections are okay, go to step  7 . If faulty connections are found and repaired, go to step  8 .
  6. Replace IPC. See INSTRUMENT PANEL CLUSTER  under REMOVAL & INSTALLATION. After repairs, go to step  8 .
  7. Replace PCM. See POWERTRAIN CONTROL MODULE under COMPUTERIZED ENGINE CONTROLS in REMOVAL, OVERHAUL & INSTALLATION article in ENGINE PERFORMANCE. After repairs, go to next step.
  8. After repairs, recheck operation of tachometer. If tachometer operates properly, repair is complete. If tachometer does not operate properly, go to step  2 .
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