Outside Temperature Display Sensor: Testing and Inspection

DIAGNOSIS AND TESTING - AMBIENT TEMPERATURE SENSOR

The ambient temperature display feature is supported by the ambient temperature sensor, a wiring circuit, the Controller Area Network (CAN) data bus and the Totally Integrated Power Module (TIPM). When the sensor is exposed to temperatures above 60° C (130° F) or if the sensor circuit is shorted, 60° C (130° F) will appear in the electronic display in place of the temperature. When the sensor is exposed to temperatures below - 40° C (- 40° F) or if the sensor circuit is open, - 40° C (- 40° F) will appear in the electronic display.

The ambient temperature sensor circuit can be diagnosed using the following Temperature System Test, and Sensor Test. If the temperature sensor and circuit are confirmed to be okay, but the temperature display is inoperative or incorrect, further testing of the Totally Integrated Power Module (TIPM) or the ElectroMechanical Instrument Cluster (EMIC) (also known as the Cab Compartment Node/CCN) may be required using a diagnostic scan tool. Refer to the appropriate diagnostic procedures.

SENSOR TEST

1. Turn the ignition switch to the OFF position. Disconnect the ambient temperature sensor from the wire harness connector.
2. Measure the resistance of the ambient temperature sensor. At - 40° C (- 40° F), the sensor resistance is 336 kilohms. At 55° C (130° F), the sensor resistance is 2.488 kilohms. The sensor resistance should read between these two values. If okay, further testing of the TIPM or the EMIC may be required using a diagnostic scan tool. Refer to the appropriate diagnostic information. If not okay, replace the ineffective ambient temperature sensor.

SENSOR CIRCUIT TEST

For complete circuit diagrams, refer to the appropriate wiring information. The wiring information includes wiring diagrams, proper wire and connector repair procedures, details of wire harness routing and retention, connector pin-out information and location views for the various wire harness connectors, splices and grounds.

1. Turn the ignition switch to the OFF position. Disconnect the ambient temperature sensor from the wire harness connector.

NOTE: Temperature readings do not update immediately. Allow up to 60 seconds after the ignition switch is turned to the ON position for readings to meet test specifications.

2. Turn the ignition switch to the ON position. The display should now read - 40° C (- 40° F). If okay, go to 3. If not okay, repair the shorted sensor return circuit or ambient temperature sensor signal circuit to the ambient temperature sensor as required.
3. Turn the ignition switch to the OFF position. Taking care not to damage the wire terminals, connect a jumper wire between the two terminals in the wire harness connector for the ambient temperature sensor.
4. Turn the ignition switch to the ON position. The display should now read 60° C (130 F). If okay, go to 5. If not okay, repair the open sensor return circuit or ambient temperature sensor signal circuit to the ambient temperature sensor as required.

NOTE: If the electronic display does not show the ambient temperature in Step 4, the vehicle may need to be driven several miles at a speed greater than 32 km/h (20 mph) for the temperature to update.

5. Turn the ignition switch to the OFF position. Remove the jumper wire. Turn the ignition switch to the ON position and wait until the display again reads - 40° C (- 40° F). Turn the ignition switch to the OFF position. Reconnect the ambient temperature sensor. Turn the ignition switch to the ON position. The display should now read the ambient temperature. If okay, the problem is intermittent. Perform further diagnosis while manipulating the related wire harnesses and components. If not okay, go to 6
6. Clear any Diagnostic Trouble Codes (DTC) that may have been set while performing the test. Perform further diagnosis of the Controller Area Network (CAN) data bus, the TIPM, the EMIC and the ambient temperature sensor.