GF88.79-P-2000FQ Heat Left/Right Outside Rearview Mirrors Function

GF88.79-P-2000FQ Heat Left/Right Outside Rearview Mirrors Function
MODEL 218

Function requirements, general
^ No overvoltage or undervoltage
^ On-board electrical system consumer shutoff not active
^ Particular (local) front power window not active

Heat left/right outside mirror, general
The heated outside mirror is activated depending on the temperature or the combination with the heated rear window (R1).
The left/right heated outside mirror function comprises the following partial functions:
^ Function sequence for temperature dependent control
^ Function sequence for control when rear window heater active

Function requirements, temperature dependent control
^ Circuit 61 ON or "PT_Rdy" (drivetrain ready) signal set
The circuit status of circuit 61 or "PT_Rdy" signal is provided by the CDI control unit (N3/9) (with diesel engine) or ME-SFI [ME] control unit (N3/10) (with gasoline engine) to the chassis CAN (CAN E) and routed by the front SAM control unit with fuse and relay module (N10/1) to the interior CAN (CAN B).

Function sequence for temperature dependent control
The mirror heater is operated depending on the following values:
- Ambient temperature
- Dewpoint temperature

Outside temperature:
The outside temperature is detected by the outside temperature sensor (B14). The front SAM control unit reads in the data of the outside temperature sensor, determines the outside temperature and transmits the data to the instrument cluster (A1) via the interior CAN (CAN B). The instrument cluster calculates the outside temperature to be displayed in consideration of the vehicle speed as well as the heat radiated by the engine and provides the corrected outside temperature to the left front door control unit (N69/1) and right front door control unit (N69/2) on the interior CAN.

Dew point temperature:
The dew point temperature is detected by the vehicle interior humidity/temperature sensor (B82) and sent over the air conditioning LIN (LIN B8) to the automatic air conditioning control and operating unit (N22/7).
The automatic air conditioning control and operating unit routes the information over the interior CAN to the left front door control unit and right front door control unit.
If the value of the dew point is not plausible or a dew point value is not available, a substitute dew point value of T = 13 °C is used.

Mirror heater is switched on:
- Outside temperature less than or equal to dew point + 2 °C (programmable via diagnosis tester)
- outside temperature < 15 °C

Mirror heater is switched off:
- Outside temperature greater than or equal to dew point + 5 °C (programmable via diagnosis tester)
- Outside temperature > 18 °C=

If the outside temperature value received is not plausible, the mirror heater is always switched on.

Function requirements, control when rear window heater active
^ Circuit 15R ON
The electronic ignition switch control unit N73) sends the circuit status of c. 15 over the interior CAN.

Function sequence for control when rear window heater active
When the rear window heater button (N22/7s1) is pressed, the request for the rear window heater is sent by the automatic air conditioning control and operating unit over the interior CAN to the rear SAM control unit with fuse and relay module (N10/2). The rear SAM control unit sends the rear window heater status over the interior CAN to the left front door control unit and right front door control unit. The mirror heater (M21/1r1) in the left outside mirror (M21/1) and mirror heater (M21/2r1) in the right outside mirror M21/2) are then switched on when the rear window heater is active.
The mirror heater is switched off, when the heated rear window is switched off.