Rear ATC Switch LED(S)/Back Lighting Inoperative
NOTE:
After making any repairs, perform BODY VERIFICATION TEST under VERIFICATION TESTS.
- Turn the ignition on. With the DRBIII®, read ATC DTCs. If the DRBIII® displays any ATC DTCs, return to the DIAGNOSTIC TROUBLE CODE IDENTIFICATION table and choose the symptom(s). See DIAGNOSTIC TROUBLE CODE IDENTIFICATION table. With the DRBIII®, reset the ATC after repair/replacement is complete. If the DRBIII® does not display any ATC DTCs, go to the next step.
- Turn the ignition on. With the DRBIII®, read the BCM DTCs. If the DRBIII® displays Headlamp Switch: Mismatch; STG; Open; or Panel Dim Output Short, refer to symptoms HEADLAMP SWITCH MISMATCH , HEADLIGHT SWITCH SHORT TO GROUND , and HEADLIGHT SWITCH OPEN under EXTERIOR LIGHTING. Refer to symptom PANEL DIMMING OUTPUT SHORT under INSTRUMENT CLUSTER. With the DRBIII®, reset the ATC after repair/replacement is complete. If the DRBIII® does not display Headlamp Switch: Mismatch; STG; Open; or Panel Dim Output Short, go to the next step.
- Turn the ignition on. Turn the ATC Power switch on. Turn the Rear System switch on the ATC Head to the Rear Control position. Turn the Fan switch on the Rear ATC Switch to the Auto position. Set the Rear Temp to the HI setting. Compare with a known good Rear ATC Switch. While looking at the display on the Rear ATC Switch, press and hold the Temp Up/Down control in the Down position. If all segments of the LEDs are operating properly as the temperature changes from HI to LO, go to the next step. If all segments of the LEDs are not operating properly as the temperature changes from HI to LO, replace the Rear ATC Switch. With the DRBIII®, reset the ATC after repair/replacement is complete.
- Turn the ignition off. Rotate the Panel Lamps Dimmer switch to the off position. Disconnect the Rear ATC Switch harness connector. See Fig 1. Turn the park lamps on. Measure the voltage of the Panel Lamps Driver circuit while rotating the Panel Lamps Dimmer switch from the off position to the full brightness position. If the voltage changes from approximately 2.5 volts to 11.5 volts, replace the Rear ATC Switch. See appropriate AUTOMATIC A/C-HEATER SYSTEMS article in HVAC. With the DRBIII®, reset the ATC after repair/replacement is complete. If the voltage does not change from approximately 2.5 volts to 11.5 volts, go to the next step.
- Turn the ignition off. Disconnect the Rear ATC Switch harness connector. See Fig 1. Disconnect the Body Control Module C3 harness connector. See Figure. Measure the resistance of the Panel Lamps Driver circuit between the Rear ATC Switch harness connector and the Body Control Module C3 harness connector. If the resistance is below 5 ohms, replace the Body Control Module. See BODY CONTROL MODULE under REMOVAL & INSTALLATION. With the DRBIII®, reset the ATC after repair/replacement is complete. If the resistance is above 5 ohms, repair the Panel Lamps Driver circuit for an open. With the DRBIII®, reset the ATC after repair/replacement is complete.