Section 13-05: Tachometer, Oil Pressure, Coolant Temperature Gauges/Warning Indicators
1993 Mustang Workshop Manual
DIAGNOSIS AND TESTING

Tachometer, Oil Pressure, Coolant Temperature Gauges/Warning Indicators

Refer to the following charts for diagnosis.  

PINPOINT TEST A: TACHOMETER INOPERATIVE, ERRATIC, WRONG INDICATION

 

A1 CHECK OPERATION  

Inoperative
GO to A2.

Erratic or wrong indication
GO to A3.

 

A2 CHECK FUSE

Yes
GO to A3.

No
REPLACE fuse.

 

A3 CHECK WIRING

  • Check for loose wiring connections in engine compartment and at instrument cluster.
  • Are all connections OK?
Yes
GO to A4.

No
SECURE loose connections.

 

A4 CHECK RESISTANCE AND VOLTAGE

  • Disconnect battery.
  • Remove instrument cluster and make resistance and voltage checks using Rotunda Digital Volt-Ohmmeter 014-00407, or equivalent at 14401 wire harness connector as follows (refer to pin locations below): Check Pin 14 resistance to chassis ground—should read 1 ohm or less. For 5.0L Check Pin 11 resistance to negative terminal of ignition coil or for 2.3L, check Pin 11 to Pin on EI module (12A297). Should be 1 ohm or less. Connect battery. Turn ignition switch ON. Check for + 12V at Pin 7. Turn ignition switch OFF. Disconnect battery.



  • Is all voltage and resistance within specifications?
Yes
GO to A5.

No
Condition is not in tachometer. SERVICE wiring.

 

A5 CHECK CONNECTOR CLIPS

  • Check for loose tachometer connector clips on rear of instrument cluster, or damaged printed circuit.
  • Are connector clips OK?
Yes
REPLACE tachometer.

No
TIGHTEN or REPLACE clips. REPLACE printed circuit.