Tachometer Inaccurate
- Disconnect 12-pin connector from back of instrument cluster. Using an ohmmeter, check for continuity between pin No. 10 and ground. See Fig 1
. If continuity is present, go to next step. If not, repair open in tachometer ground circuit.
Courtesy of FORD MOTOR CO.
- Start and idle engine. Set voltmeter on 10-volt range. Measure and record voltage at tachometer feed side (negative side, Green wire) of ignition coil. Measure voltage at pin No. 9 of 12-pin connector cluster. Voltage should be the same as that measured at tachometer feed side of ignition coil. If okay, repair open in tachometer feed circuit. If not, go to next step.
- Turn ignition switch to "RUN" position. Using a voltmeter, check for battery voltage at pin No. 8. If voltage is present, replace tachometer assembly. If not, repair open in tachometer voltage supply circuit.