Heated Glass Element: Description and Operation

Heated Rear Window (Z1)






• By pressing button - E - with ignition switched on, Vehicle electrical system control module (J519) is activated by a ground signal (signal remains on for duration of button operation). As soon as the Vehicle electrical system control module rear window defroster switches on (only when the engine is running) the indicator lamp in the button - E - comes on (the vehicle electrical system control module emits a positive signal). Rear window heater is switched off by pressing button - E - again and by switching ignition off. Refer to and Vehicle Owner's Manual.

• If the voltage measured on terminal 30 on the Vehicle electrical system control module is below a valued stored in the vehicle electrical system control module, then the rear window defogger will be switched off completely or the power will be reduced to take the load off the generator. Refer to Vehicle diagnosis, testing and information system (VAS5051B) under "Guided Fault Finding" (for the vehicle electrical system control module).

• The rear window defogger is controlled by the vehicle electrical system control module only when the engine is running. When the engine is off, there is no activation and no message from the vehicle electrical system control module. The LED in the button - E - does not come on, or will go out shortly after the button is pushed. Refer to the Owner's Manual.






• If it is necessary to switch off the rear window defogger for a brief period due to low voltage from the vehicle electrical system control module, the indicator lamp in the defogger switch remains on - E -. If the defogger is going to be switched off for a longer period, then the vehicle electrical system control module will switch the lamp off.

• The test for switching on the rear window defogger is described in Guided Fault Finding for the vehicle electrical system control module and for the A/C system. Refer to Vehicle diagnosis, testing and information system (VAS5051B) under "Guided Fault Finding" (for vehicle electrical system control module).

• The rear window defogger switches off by itself after approximately 10 minutes by the vehicle electrical system control module if the outside temperature is above 0 °C.

• With ambient temperatures less than 0 °C in vehicles which were built from beginning of production, heated rear window is switched off by vehicle electrical system control module after approximately 20 minutes. At a later point in time, vehicle electrical system control modules are installed (introduction not yet finalized) in which Heated Rear Window remains switched on until ignition is switched off (it can be switched off and back on again manually at any time). If temperature rises above 0 °C in the course of a driving cycle, rear window defroster is switched off on completion of operating period stored in vehicle electrical system control module (approximately 10 minutes).