Electric Outside Mirrors, Function - GF88.79-D-0003TSA
Model 907
with code F68 (Exterior mirrors, electr. adjustable and heated)
Block diagram
This function description describes a left-hand drive vehicle. Right-hand drive vehicles are to be observed mirror inverted with regard to the designations of the electric components.
Function requirements
- Circuit 15R activated.
The electronic ignition lock control unit (EZS) transmits the circuit status of circuit 15 via the interior CAN to the front door control units. The function description of the electric outside mirrors includes the following functions:
- Outside mirror glass adjustment function
- Fold-in outside mirror, function
- Outside mirror heating function.
Outside mirror glass adjustment function
The mirror glasses of the outside mirrors can be electrically adjusted in a horizontal and vertical manner.
The respective outside mirror is selected via the corresponding outside mirror adjustment switch in the driver's door switch module. By actuating the outside mirror adjustment switch, this directly actuates the up-and-down mirror adjustment motor as well as the inward and outward mirror adjustment motor of the selected outside mirror.
Fold-in outside mirror, function
Vehicles with code F64 (electric folding outside mirror)
The outside mirror housings can be folded in and out electrically in pairs.
By actuating the fold in/out outside mirror switch on the driver's door switch module, the housings of the outside mirror are folded in and out.
The power folding mirror motors are directly actuated by the outside mirror fold-in/fold-out switch.
Heating outside mirror, function
The mirror heaters can be activated in combination with the heated rear window function or depending on the outside temperature. If several requests are present simultaneously, the mirror heaters are always operated at the highest possible actuation power resulting from the corresponding actuation source. The possible actuation sources have the following priority:
- Request via heated rear window function
- Request via temperature-dependent control
The driver's door control unit directly actuates the mirror heater in the left outside mirror. The front passenger door control unit directly actuates the mirror heater in the right outside mirror.
The outside mirror heating function comprises the following partial functions:
- Function sequence for mirror heater when rear window is switched on
- Function sequence for temperature-dependent mirror heater
Function sequence for mirror heater when rear window is switched on
Vehicles with code H22 (heated rear window) If the heated rear window function is active, the SAM control unit (N10) transmits the "rear window heater active" status via the interior CAN to the driver's door control unit and to the front passenger door control unit. The driver's door control unit then actuates the mirror heater in the left outside mirror; the front passenger door control unit actuates the mirror heater in the right outside mirror. The mirror heaters are actuated as long as the request is present at a capacity of 100 %. When heated rear window function is switched off, the mirror heaters are also switched off.
If adjustments affecting the temperature, air distribution, or air volume are made on the automatic air conditioning control and operating unit while the heated rear window is switched on, the symbol for the rear window heater and the corresponding set values are briefly displayed on the Audio/COMAND display.
Detailed information about the rear window heater function is contained in the separate function description "Rear window heater function".
Additional function requirements for temperature-dependent mirror heater
- "Engine running" or "Drive train operational" signal on.
The "engine running" or "drivetrain operational" signal is transmitted by the CDI control unit (for diesel engines) or the ME-SFI control unit (for gasoline engines) via the drive train CAN, powertrain control unit, suspension FlexRay, electronic ignition lock (EZS) control unit, and interior CAN to the driver's door control unit and the front passenger door control unit.
Function sequence for temperature-dependent mirror heater
The mirror heaters are operated depending on the following values:
- Outside temperature
- Dewpoint temperature
The front door control units compare both values with each other and switch the mirror heaters on if a dew point temperature of 2 °C below the outside temperature is detected.
Outside temperature
The outside temperature is recorded by the outside temperature sensor. The SAM control unit reads in the signal from the outside temperature sensor directly, calculates the outside temperature, and transmits it via the interior CAN, electronic ignition lock control unit (EZS) and user interface CAN to the instrument cluster. The instrument cluster calculates the outside temperature to be displayed, taking the vehicle speed as well as the engine waste heat into account, and transmits the corrected outside temperature value via the user interface CAN, electronic ignition lock (EZS) control unit and interior CAN to the driver's door control unit and the front passenger door control unit.
If the outside temperature value received is implausible or not available, the mirror heaters are always switched on.
Dewpoint temperature
The dew point temperature is the temperature at which water vapor would condense in the outside air. The glass in the mirrors would fog up.
The dew point temperature is sensed by the humidity and temperature sensor in the rain and light sensor. The SAM control unit reads in the signal of the rain and light sensor via the rain and light sensor LIN and transmits this via the interior CAN to the driver's door control unit and to the front passenger door control unit.
The driver's door control unit actuates the mirror heater in the left outside mirror; the front passenger door control unit actuates the mirror heater in the right outside mirror.
If the value of the dew point is implausible or unavailable, a substitute value of 13 °C is used.
The mirror heaters are actuated via a signal with pulse width
modulation (PWM), i.e. performance-controlled.
The following tables show the actuation of the mirror heaters.
| Restart or temperature range change at decreasing temperature | Thawing phase | Holding phase | ||
|---|---|---|---|---|
| Temperature range | Duration | PWM value | Duration | PWM value |
| > 5 °C | 2 min | 100 % | Temperature-dependent | 30 % |
| 5 to -5 °C | 5 min | 100 % | Temperature-dependent | 70 % |
| < -5 °C | 10 min | 100 % | Temperature-dependent | 100 % |
| Temperature range change at increasing temperature | Thawing phase | Holding phase | ||
|---|---|---|---|---|
| Temperature range | Duration | PWM value | Duration | PWM value |
| < -2 °C | 10 min | 100 % | Temperature-dependent | 100 % |
| -2 to 8 °C | 5 min | 100 % | Temperature-dependent | 70 % |
| > 8 °C | 2 min | 100 % | Temperature-dependent | 30 % |
The mirror heaters are switched off at the following temperatures:
- Outside temperature ≥ 5 °C above the dew point (via programmable diagnostic tester)
- Outside temperature > 18 °C
| Overview of system components, electric outside mirrors | GF88.79-D-9997TSA |