Tachometer: Testing and Inspection
Gauge reads zero, full scale, too high or low1. Refer to Computer Controls, for fault diagnosis of tachometer signal. Computers and Control Systems
2. Check harness wiring and connection from Instrument pack pin 24 (24-way connector) and Engine Management Control Module (ECM).
3. If all previous checks prove correct remove and open the instrument pack. Examine flexi-circuit connections to tachometer, ensuring correct and secure installation.
4. Check continuity of flexi-circuit tracks to tachometer connections.
5. Check continuity of speedometer driver windings by disconnecting from flexi-circuit and testing between the upper central connection pin and each of the other two pins. If open circuit is recorded renew tachometer.