Temp Display Inoperative Or Wrong

Possible Causes:

• Ambient Temperature Sensor
• Ambient Temperature Sensor Signal Circuit Short To Voltage
• Ambient Temperature Sensor Signal Circuit Open
• Ambient Temperature Sensor Signal Circuit Short To Ground
• Ambient Temperature Sensor Signal Circuit Short To Ground Circuit
• Ambient Temperature Sensor Ground Circuit Open
• Body Control Module
• Compass/Mini-Trip Computer

Testing

NOTE: Ensure that the CMTC is communicating on the PCI Bus before proceeding with this test.
NOTE: The Ambient Temperature Sensor is hardwired to the BCM. Ambient temperature information is transmitted to the CMTC via the PCI Bus.
NOTE: After any repair for an Ambient Temperature Sensor problem, the vehicle must be driven over 3 miles above 25 MPH to update the CMTC display.
1. Turn the ignition off. Disconnect the Ambient Temperature Sensor harness connector. Measure the resistance of the Ambient Temperature Sensor using the following temperature/resistance values. See AMBIENT TEMPERATURE SENSOR  table. Is the Ambient Temperature Sensor resistance measurement between the min/max specifications? If yes, go to next step. If no, replace the Ambient Temperature Sensor. Perform BODY VERIFICATION TEST  .
2. Turn the ignition off. Ensure that the Interior lights are off. Ensure that the Exterior lights are off. Disconnect the DRBIII(R). Ensure that all doors are closed. Disconnect the Ambient Temperature Sensor harness connector. Measure the voltage between the Ambient Temperature Sensor Signal circuit and ground. Is there any voltage present? If yes, repair the Ambient Temperature Sensor Signal circuit for a short to voltage. Perform BODY VERIFICATION TEST  . If no, go to next step.
3. Disconnect the Ambient Temperature Sensor harness connector. Turn the ignition on. Measure the voltage between the Ambient Temperature Sensor Signal circuit and the Sensor ground circuit. Is the voltage above 4.5 volts? If yes, replace the Compass/Mini-Trip Computer. See OVERHEAD CONSOLES - LIBERTY for REMOVAL & INSTALLATION. Perform BODY VERIFICATION TEST  . If no, go to next step.
4. Turn the ignition off. Disconnect the Ambient Temperature Sensor harness connector. Disconnect the BCM C2 harness connector. Measure the resistance between ground and the Ambient Temperature Sensor Signal circuit. Is the resistance below 5.0 ohms? If yes, repair the Ambient Temperature Sensor Signal circuit for a short to ground. Perform BODY VERIFICATION TEST  . If no, go to next step.
5. Turn the ignition off. Disconnect the Ambient Temperature Sensor harness connector. Disconnect the BCM C2 harness connector. Measure the resistance of the Sensor Signal circuit to the Sensor Ground circuit in the Sensor connector. Is the resistance below 5.0 ohms? If yes, repair the Ambient Temperature Sensor Signal circuit for a short to the Ambient Temperature Sensor Ground circuit. Perform BODY VERIFICATION TEST  . If no, go to next step.
6. Turn the ignition off. Disconnect the Ambient Temperature Sensor harness connector. Disconnect the BCM C2 harness connector. Measure the resistance of the Ambient Temperature Sensor Signal circuit between the Sensor connector and the BCM C2 connector. Is the resistance above 5.0 ohms? If yes, repair the Ambient Temperature Sensor Signal circuit for an open. Perform BODY VERIFICATION TEST  . If no, go to next step.
7. Turn the ignition off. Disconnect the Ambient Temperature Sensor harness connector. Disconnect the BCM C2 harness connector. Measure the resistance of the Sensor Ground circuit between the Sensor connector and the BCM C2 connector. Is the resistance above 5.0 ohms? If yes, repair the Ambient Temperature Sensor Ground circuit for an open. Perform BODY VERIFICATION TEST  . If no, replace and program the Body Control Module. See OVERHEAD CONSOLES - LIBERTY for REMOVAL & INSTALLATION. Perform BODY VERIFICATION TEST  .