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Tachometer Inaccurate

  1. Check fuse No. 12. See Figure . If fuse is okay, go to next step. If fuse is blown, replace fuse and retest system.
  2. Check for loose wiring connections in engine compartment and at instrument cluster. If connections are okay, go to next step. If any connections are loose, secure properly and retest system.
  3. Disconnect negative battery cable. Remove instrument cluster. See INSTRUMENT CLUSTER under REMOVAL & INSTALLATION. Disconnect cluster connectors C250 and C251. Measure resistance between ground and cluster connectors C251 terminal No. 13 (Black/Yellow wire for non-flex fuel vehicles and Brown wire for flex fuel vehicles) and C251 terminal No. 8 (Tan/Yellow wire). If resistances are less than 3 ohms, go to next step. If resistances are more than 3 ohms, tachometer is not at fault. Inspect and repair appropriate circuit, and retest system.
  4. Connect battery negative cable. Turn ignition switch to RUN position. Check for battery voltage at cluster connector C250 terminal No. 10 (Red/Yellow wire). Turn ignition switch to OFF position. If battery voltage exists, go to next step. If battery voltage does not exist, tachometer is not at fault. Inspect and repair Red/Yellow wire between fuse panel and instrument cluster. Retest system.
  5. Check for loose tachometer connector clips on rear of instrument cluster or damaged instrument cluster printed circuit. If connector clips are okay, go to next step. If clips are faulty, tighten or replace clips. Replace instrument cluster printed circuit and retest system.
  6. Check Clean Tach Output (CTO) circuit for open or short. See appropriate TESTS W/CODES article in the ENGINE PERFORMANCE section. If CTO circuit is okay, replace tachometer and retest system. If CTO circuit has open or short, replace PCM and retest system.
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