GF88.79-P-2000T Heat Left/Right Exterior Rearview Mirrors, Function

GF88.79-P-2000T Heat Left/right Exterior Rearview Mirrors, Function

Component Identification:

The mirror heaters (M21/1r1 and M21/2r1) each consist of one heating resistor located on a foil on the rear of the mirror lens.

Function prerequisites
^ Circuit 61 (engine running)
^ Power window not operated
^ No overvoltage or undervoltage

Function
The outside temperature is measured by the outside temperature indicator temperature sensor (14) and forwarded to the driver's side SAM control module with fuse and relay module (N10/1).

The latter relays this information to the CAN, class B bus. The front left door control module (N69/1) and right (N69/2) evaluates the information and switch the mirror heaters (M21/1r1 and M21/2r1) ON or OFF accordingly.

In addition to the outside temperature, the humidity (dew point) is also used for control.
If the outside temperature value received is implausible, the mirror heater is always switched on. If the dew point value is not available, the switch-on value is set to 13 °C.