Operation CHARM: Car repair manuals for everyone.

Temperature Gauge: Testing and Inspection

Engine coolant temperature should be measured with a thermometer and compared to gauge reading prior to performing gauge diagnostic procedures. If it is determined that actual coolant temperature does not match gauge indication, proceed as follows:

1. Place ignition switch in On position, then disconnect coolant temperature sending unit connector and observe gauge; needle should drop to lowest position on scale. If gauge does not perform as specified, continue with procedure. If not, proceed as follows:
a. Connect a suitable jumper wire between sending unit wiring and ground and observe gauge; needle should move to highest position on scale.
b. If gauge performs as specified, replace sending unit; if not, continue with procedure.
2. Place ignition switch in Off position and disconnect battery ground cable, then remove instrument cluster and bezel.
3. Probe cavity J of printed circuit No. 1 connector to determine if there is continuity to a good ground source; no continuity should exist. If there is continuity, repair short in circuit as necessary.
4. Check for continuity between cavity J and sending unit wiring connector. If continuity exists, replace gauge; if not, repair open in circuit as necessary.