XJ-12 (X300) V12-6.0L (1995)
Tachometer: Component Tests and General Diagnostics
Gauge reads zero, full scale, too high or low
1. Refer to Computer Controls, for fault diagnosis of tachometer signal. See: Powertrain Management/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.