Tachometer Inaccurate
- Turn ignition switch to OFF position. Partially remove instrument cluster to access cluster connectors. See INSTRUMENT CLUSTER under REMOVAL & INSTALLATION. Turn ignition switch to RUN position. Check for battery voltage at cluster connector C2, pin No. 10 (Red/Yellow wire). See Figure and Figure . If battery voltage is present, go to next step. If battery voltage is not present, repair circuit No. 640 (Red/Yellow wire) and/or fuse No. 15 for open and retest system. See Figure .
- Measure resistance between ground and cluster connector C2, pin No. 7 (Black/White wire) or for 4.6L engine only, cluster connector C2, pin No. 9 (Black/Yellow wire). If resistance is 5 ohms or less, go to next step. If resistance is more than 5 ohms, repair circuit No. 397 (Black/White wire), or circuit No. 651 (Black/Yellow wire) for open and retest system.
- Turn ignition switch to OFF position. Disconnect cluster connector C2. Install Breakout Box (014-00950) to PCM connector. See Fig 1 . With an ohmmeter, measure resistance of circuit No. 659 (Orange /White wire) from breakout box pin No. 48 to cluster connector C2, pin No. 8 (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. 659 (Orange/White wire) for open and retest system.
- Reconnect instrument cluster connector C2. Check for continuity from tachometer connector clips to instrument cluster printed circuit. If the is continuity, go to next step. If continuity is not present, replace connector clips and retest system.
- Using an ohmmeter, check circuits for continuity according to INSTRUMENT CLUSTER CONTINUITY table. If there is continuity at all circuits, replace speedometer/tachometer assembly and retest system. If continuity is not present at all circuits, replace instrument cluster printed circuit and retest system.
INSTRUMENT CLUSTER CONTINUITY
| Cluster Connector - Pin No. (Wire Color) | Function |
|---|---|
| C2-7 (BLK/WHT) | Ground |
| C2-9 (BLK/YEL) | Ground (4.6L Engine) |
| C2-10 (RED/YEL) | Run/Start Power |
| C2-8 (TAN/YEL) | Tachometer Input |