Temperature Sensor (Gauge): Testing and Inspection

Coolant Temperature Gauge Sending Unit Test:

1. Disconnect the YEL/GRN wire from the sending unit, and with the engine cold, use an ohmmeter to measure resistance between the positive terminal and the engine (ground).
2. Check the temperature of the coolant.
3. Run the engine, and measure the change in resistance with the engine at operating temperature (radiator fan comes on).

Coolant Temperature Gauge Sending Unit Test:

4. If the readings you get are substantially different from the specifications above, replace the coolant temperature gauge sending unit.