Switch, Defogger: Operation
When the momentary push button switch for the rear window defogger system, also known as the Electric Back Light (EBL), is pressed to on, a request signal is sent to the Body Control Module (BCM) over hard-wired circuits to energize the EBL relay (when all required conditions are valid, e.g. roof closed, ignition Run, etc.) located in the Power Distribution Center (PDC). When the EBL relay is energized, fused battery current is directed to the rear window defogger grid lines. The grid lines heat the glass to help clear the rear window of fog or frost.
An indicator lamp in the instrument cluster illuminates when the EBL system is on. The BCM contains the EBL system control circuitry, including the timer logic.
The EBL system turns off automatically after twenty minutes of initial operation. Each following activation cycle of the EBL system will last twenty minutes. After ten minutes (fifteen minutes when equipped with sun-roof) the EBL system turns off automatically if the engine is NOT running (<960 RPM). In this situation the Rear Defog indicator lamp in the IPC will remain ON for the duration of the 20 minutes cycle timer.
The EBL system automatically turns off after an initial programmed time interval of about twenty minutes, as long as the ignition is left in the Run position with engine running. If a rear window defogger switch is pressed to on again after the initial time interval has expired, the EBL system will automatically turn off after about twenty minutes. The EBL system will also turn off if the ignition is set to OFF, or by manually pressing the rear window defogger switch a second time.
The rear window defogger switch is diagnosed using a scan tool. Refer to DIAGNOSTIC CODE INDEX . There are no relevant DTCs for the switch; use the monitoring function of the WiTech to monitor the BCM inputs.
The rear window defogger switch cannot be adjusted or repaired. Check the wiring and if the rear window defogger switch is inoperative or damaged, the entire upper accessory switch pod must be replaced. Refer to POD, SWITCH, REMOVAL .