HVAC Control Illumination Lamps Inoperative

Possible Causes are:

• HVAC CONTROL ILLUMINATION INOPERATIVE
• CONTROL HEAD OPEN GROUND CIRCUIT
• PANEL LAMPS DRIVER CIRCUIT OPEN
• BCM (HVAC ILLUMINATION)

1. Disconnect the appropriate HVAC Control panel connector C1 (for manual) or C2 (for automatic system). Connect a test light between the HVAC ground circuit and Panel Lamps Driver circuit in the HVAC connector(s). Turn on the panel lamps and observe the test light. Did the test light illuminate? If yes, replace the Heater-A/C Control Panel Assembly. Perform BODY VERIFICATION TEST VER 1  under VERIFICATION TESTS. If no, go to next step.
2. Turn ignition off. Disconnect the HVAC connectors. Measure the resistance of the Ground circuit in the HVAC C1 or C2 connector. See WIRING DIAGRAMS  to determine which HVAC connector. Is the resistance less than 5 ohms? If yes, go to next step. If no, repair the open HVAC Ground Circuit. Perform BODY VERIFICATION TEST VER 1  under VERIFICATION TESTS.
3. Turn ignition off. Disconnect the HVAC connectors. Disconnect the BCM C1 connector. Measure the resistance of the Panel Lamps Driver circuit between the BCM C1 connector and the HVAC C1 or C2 connector. See WIRING DIAGRAMS  to determine which HVAC connector. Is the resistance less than 5 ohms? If yes, go to next step. If no, repair the open in the Panel Lamps Driver circuit. Perform BODY VERIFICATION TEST VER 1  under VERIFICATION TESTS.
4. If there are no possible causes remaining, replace the Body Control Module. Perform BODY VERIFICATION TEST VER 1  under VERIFICATION TESTS.