Temperature 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
• Powertrain Control Module
• Compass/Mini Trip Computer

Testing

1. Ensure that the CMTC is communicating on the PCI Bus before proceeding. The ambient temperature sensor is hardwired to the PCM. Ambient temperature information is transmitted to the CMTC via the PCI Bus. Turn the ignition off. Disconnect the ambient temperature sensor harness connector. Measure the resistance of the ambient temperature sensor. See AMBIENT TEMPERATURE SENSOR RESISTANCE  table. If the ambient temperature sensor resistance measurement is between the min/max specifications, go to next step. If the resistance is not between the min/max specifications, replace the Ambient Temperature Sensor. See AUTOMATIC A/C-HEATER SYSTEMS - CONCORDE, INTREPID & 300M article in HVAC.
2. Ensure that the interior and exterior lights are off. Disconnect the scan tool. Ensure all doors are closed. Measure the voltage between the ambient temperature sensor signal circuit and ground. If there is any voltage present, repair the ambient temperature sensor signal circuit for a short to voltage. If there is not any voltage, go to next step.
3. With the ambient temperature sensor harness connector still disconnected, turn the ignition on. Measure the voltage between the ambient temperature sensor signal circuit and the sensor ground circuit. If the voltage is more than 4.5 volts, replace the CMTC. See OVERHEAD CONSOLES - CONCORDE, INTREPID & 300M article. If the voltage is 4.5 volts or less, go to next step.
4. Turn the ignition off. Disconnect the PCM C2 harness connector. Measure the resistance between ground and the ambient temperature sensor signal circuit. If the resistance is below 5 ohms, repair the ambient temperature sensor signal circuit for a short to ground. If the resistance is 5 ohms or more, go to next step.
5. Measure the resistance of the sensor signal circuit to the sensor ground circuit at the sensor connector. If the resistance is less than 5 ohms, repair the ambient temperature sensor signal circuit for a short to the ambient temperature sensor ground circuit. If the resistance is 5 ohms or more, go to next step.
6. Measure the resistance of the ambient temperature sensor signal circuit between the sensor connector and the PCM C2 connector. If the resistance is more than 5 ohms, repair the ambient temperature sensor signal circuit for an open. If the resistance is 5 ohms or less, go to next step.
7. Measure the resistance of the sensor ground circuit between the sensor connector and the PCM C2 connector. If the resistance is more than 5 ohms, repair the ambient temperature sensor ground circuit for an open. If the resistance is 5 ohms or less, replace the PCM. See POWERTRAIN CONTROL MODULE  under REMOVAL & INSTALLATION.