Tachometer Does Not Reflect Correct Engine Speed
WARNING: This page is about a different car, the 1997 Mercury Cougar and 1997 Ford Thunderbird. However, it is still accessible from the selected car via links, so may be relevant.
- Check CLUSTER (5-amp) fuse located in primary fuse panel. If fuse is okay, go to next step. If fuse is not okay, replace fuse and retest system.
- Check for loose wiring connections in engine compartment and at instrument cluster. If all connections are clean and tight, go to next step. If connections are not clean and tight, repair/replace as necessary and retest system.
- Disconnect negative battery cable. Remove instrument cluster. See INSTRUMENT CLUSTER under REMOVAL & INSTALLATION. Disconnect cluster connector C251. See Figure. Measure resistance between ground and cluster connector C251, pin No. 6 (Red/Yellow wire). If resistance is less than 5 ohms, go to next step. If resistance is more than 5 ohms, repair open in Red/Yellow wire and retest system.
- Disconnect Powertrain Control Module (PCM) located behind right cowl panel. See Fig 1. Measure resistance between cluster connector C250, pin No. 9 (White/Pink wire) and PCM connector pin No. 48 (White/Pink wire). If resistance is less than 5 ohms, go to next step. If resistance is more than 5 ohms, repair open in White/Pink wire and retest system.
- Reconnect negative battery cable. Turn ignition switch to RUN position. Measure voltage between ground and cluster connector C251, pin No. 6 (Red/Yellow wire). If battery voltage is present, go to next step. If battery voltage is not present, check CLUSTER (5-amp) fuse and replace as necessary. If fuse is okay, repair open in Red/Yellow wire and retest system.
- Check for loose tachometer clips on rear of instrument cluster printed circuit. If clips are okay, replace tachometer and retest system. If clips are loose, tighten or replace clips as necessary. If problem persists, replace printed circuit. See PRINTED CIRCUIT under REMOVAL & INSTALLATION.