Ambient Temperature Sensor / Switch HVAC: Testing and Inspection

AMBIENT TEMPERATURE SENSOR

The thermometer function is supported by the ambient temperature sensor, the Totally Integrated Power Module (TIPM), the Controller Area Network (CAN) data bus circuit, and the instrument cluster or Cab Compartment Node (CCN) compass/temperature display unit.

If the display shows "O" (-45° C (-49° F)) or "SC" (60° C (140° F)), there is an OPEN or SHORT CIRCUIT that must be repaired.

The ambient temperature sensor circuit can also be diagnosed using the following Sensor Test, and Sensor Circuit Test. If the temperature sensor and circuit are confirmed to be OK, but the temperature display is inoperative or incorrect, replace the instrument cluster or CCN assembly.

SENSOR TESTING

1. Turn the ignition switch to the OFF position. Disconnect and isolate the battery negative cable.

2. Disconnect the ambient temperature sensor wire harness connector.

3. Measure the resistance of the ambient temperature sensor. At room temperature (approx. 20° C (68° F)), the sensor resistance should be between 9-11 Kilohms (9000-11000 ohms). The sensor resistance should read between these two values. If OK, refer to the appropriate diagnostic information to continue diagnosis of the Totally Integrated Power Module (TIPM), the Controller Area Network (CAN) data bus circuit, and the instrument cluster or CCN. If not OK, replace the inoperative ambient temperature sensor.