Heated Glass Element: Description and Operation

Interlinkage Of Rear Window Defroster:

The rear window defroster function is started when the rear window defroster switch on the heater pushbutton control module (N18) or A/C pushbutton control module (N19) or A/C pushbutton control module (automatic A/C) (N22) is actuated. The voltage-coded switch signal is received at the input of the signal acquisition and actuation module (SAM) (N10/1). The SAM (N10/1) transmits the instruction " rear window defroster ON" to the PSE control module (combined, A37) via the CAN bus. Moreover, the SAM (N10/1) switches on the indicator LED in the rear window defroster switch. The PSE control module (A37) controls the rear window defroster using a load relay.

The SAM (N10/1) transmits the signal "rear window defroster off" to the PSE (A37), when

- circuit 15R off is recognized,
- low voltage less than 11 V is recognized,
- an ATA alarm is tripped,
- the rear window defroster switch is pressed again,
- however after expiration of a delay time of 12 min. at the latest

The PSE (A37) then switches off the rear window defroster. The LED indicator goes out. When switched off because the voltage is too low the LED indicator in the switch flashes at a frequency of 1.5 Hz.


NOTE: On model 210.2 the heating wire in the rear window defroster is also used as a glass breakage sensor for the interior protection.