ATC Temperature Control Incorrect In Sun Or Shade

Possible Causes:

• Check Sun Sensor Voltage
• Sun Sensor Signal Circuit Short To Voltage
• Sun Sensor Open/High
• Sensor Ground Open
• Sun Sensor Signal Circuit Open
• Body Control Module - Sun Sensor Open/High

Testing

NOTE: Perform the ATC System Test before attempting to diagnose this symptom to ensure there are no DTC's. See ATC SYSTEM TEST  .
1. Disconnect the sun sensor/VTSS LED harness connector. See Figure . With the scan tool, read the sun sensor voltage. If the voltage is 4.8 volts or less, replace the BCM. See BODY CONTROL MODULE  under REMOVAL & INSTALLATION. If the voltage is 4.8 volts or more, go to next step.
2. Turn ignition on. Measure the voltage of the sun sensor signal circuit. If the voltage is 5.2 volts or more, repair the sun sensor signal circuit for a short to voltage. If no short to voltage is found, replace the BCM. See BODY CONTROL MODULE  under REMOVAL & INSTALLATION. If the voltage is 5.2 volts or less, go to next step.
3. Connect a jumper wire between the sun sensor signal circuit and the signal ground circuit in the sensor connector. With the scan tool, read the sun sensor voltage. If the scan tool displays SUN SENSOR: BELOW .2 VOLTS, replace the sun sensor. See AUTOMATIC A/C-HEATER SYSTEMS - CONCORDE, INTREPID & 300M article in HVAC. If not, go to next step.
4. Connect a jumper wire between the sun sensor signal circuit and ground. With the scan tool, read the sun sensor voltage. If the scan tool displays SUN SENSOR: BELOW .2 VOLTS, repair the sensor ground circuit for an open. If not, go to next step.
5. Disconnect the BCM C2 harness connector. See Figure . Measure the resistance of the sun sensor signal circuit between the BCM C2 connector and the sensor connector. If the resistance is 5 ohms or less, replace the BCM. See BODY CONTROL MODULE  under REMOVAL & INSTALLATION. If the resistance is 5 ohms or more, repair the sun sensor signal circuit for an open.