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Tachometer Inaccurate

  1. Turn ignition switch to OFF position. Partially remove instrument cluster to gain access to cluster connectors. See INSTRUMENT CLUSTER  under REMOVAL & INSTALLATION. With a voltmeter, check voltage at cluster connector C1, pin No. 13 (Red/Yellow wire). If battery voltage is present, go to next step. If battery voltage is not present, repair open in circuit No. 640 (Red/Yellow wire).
  2. Using and ohmmeter, measure resistance between cluster connector C3, pin No.8 (Black/Yellow wire) and ground, and cluster connector C2, pin No. 2 (Black/White wire) and ground. If resistances are 3 ohms or less, go to next step. If resistances are more than 5 ohms, repair circuit No. 398 (Black/Yellow wire) and circuit No 570 (Black/White wire) for open. Retest system.
  3. Turn ignition switch to OFF position. Disconnect cluster connector C1. Disconnect ignition coil or DIS. Using an ohmmeter, measure resistance of circuit No. 11 (Tan/Yellow wire) from ignition coil connector or DIS connector to cluster connector C1, pin No. 15 (Tan/Yellow wire). If resistance is 1.8 ohms or less, go to next step. If resistance is more than 1.8 ohms, repair circuit No. 11 (Tan/Yellow wire) for open. Retest system.
  4. Reconnect cluster connector C1. Using an ohmmeter, check for continuity from tachometer connector clips to instrument cluster printed circuit. If there is continuity, go to next step. If no continuity, replace connector clips and retest system.
  5. Using an ohmmeter, check each of the following circuits for continuity from tachometer connector clips to cluster connector:
    • Cluster connector C1, pin No. 16 (Black/White wire) circuit No. 397.
    • Cluster connector C3, pin No. 8 (Black/Yellow wire) circuit No. 398.
    • Cluster connector C1, pin No. 13 (Red/Yellow wire) circuit No. 640.
    • Cluster connector C1, pin No. 15 (Tan/Yellow wire) circuit No. 11.

If there is continuity in all circuits, replace speedometer/tachometer assembly. Retest system. If there is not continuity in all circuits, replace instrument cluster printed circuit. Retest system.

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