The instrument panel cluster (IPC) applies 5 volts to the ambient air temperature sensor. The ambient air temperature sensor is a thermistor which varies in resistance as the temperature changes. As the resistance of the ambient air temperature sensor increases, the IPC senses a larger voltage drop across the sensor, indicating a lower temperature. As the resistance of the ambient air temperature sensor decreases, the IPC senses a smaller voltage drop across the sensor, indicating a higher temperature. The IPC is responsible for displaying the temperature and converting to degrees Fahrenheit if necessary.

The following table will be used to measure the resistance of the ambient air temperature sensor and compare it with the actual ambient temperature. The driver information center (DIC) temperature display accuracy should be within 5 degrees of the actual temperature. The actual temperature should not be taken from a radio station, a sign displaying the temperature, etc. A temperature measuring tool such as a thermometer should be used. Some temperature measuring tools may be within 5 degrees of the actual temperature. Make sure to consult the manufacturer for the accuracy of the tool. This comparison can make the DIC temperature display seem off by 5-10 degrees of the actual temperature when it is not.

If the ambient air temperature sensor resistance is less than 328 ohms, the IPC displays 'SC' (short circuit) in the DIC and this corresponds to a temperature of 125°C (257°F). If the ambient air temperature sensor resistance is greater than 353.37K ohms, the IPC displays 'OC' (open circuit) in the DIC and this corresponds to a temperature less than -40°C (-40°F). The IPC displays '- -' in the DIC when the IPC receives an invalid signal or there is a loss of serial data communication.

The IPC detects that the ambient air temperature sensor voltage is less than 0.4 volt or greater than 4.9 volts.

Schematic Reference

Instrument Cluster Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Driver Information Center (DIC) Description and Operation

Electrical Information Reference

Scan Tool Reference

Control Module References for scan tool information.

1. Ignition OFF, disconnect the ambient air temperature sensor.
2. Ignition OFF, test for less than 1 ohm between the low reference circuit terminal B and ground.

⇒	If greater than the specified range, test the low reference circuit for an open/high resistance. If the circuit tests normal replace the IPC.

3. Ignition ON, verify that OC is displayed on the DIC display.

⇒	If not the specified value, test the signal circuit terminal A for a short to ground. If the circuit tests normal replace the IPC.

4. Ignition ON, install a 3-amp fused jumper wire between the signal circuit terminal A and the low reference circuit B. Verify that SC is displayed on the DIC display.

⇒	If not the specified value, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal replace the IPC.

5. If all circuits test normal, replace the ambient air temperature sensor.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.