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Home >> Ford >> 2001 >> Excursion 7.3 F, 4WD >> Repair and Diagnosis >> Accessories & Equipment >> Gauges & Instrument Panels >> Instrument Panels - Analog - Excursion & F250-F550 Super Duty >> System Tests >> Test I: Tachometer Reads Incorrectly

Test I: Tachometer Reads Incorrectly

  1. Turn ignition switch to LOCK position. Remove instrument cluster to gain access to instrument cluster harness connectors. See REMOVAL & INSTALLATION . Disconnect instrument cluster 12-pin harness connector C250A (5.4L) or instrument cluster 16-pin harness connector C250B (6.8L). Measure resistance between ground and instrument cluster 12-pin harness connector C250A terminal No. 1 (Black/Yellow wire) or instrument cluster 16-pin harness connector C250B terminal No. 9 (Black/White wire). See Figure (5.4L) or Figure (6.8L). If resistance is 5 ohms or less, go to next step. If resistance is more than 5 ohms, repair open in Black/Yellow or Black/White wire between instrument cluster and ground point. Ground point is located at rear of left front fender. See WIRING DIAGRAMS . Retest system operation.
  2. Diagnose Clean Tach Out (CTO) circuit for opens or shorts. See appropriate SELF-DIAGNOSTICS article in ENGINE PERFORMANCE. Repair as necessary. Retest system operation. If CTO circuit is okay, replace instrument cluster. See REMOVAL & INSTALLATION . Retest system operation.
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