Heating Of Mirror Glass Of Outside Mirror, Basic Function - GF88.79-P-1001A
Model All (4xWD) Model All (CAR)
Overview
This document contains the following information:
- General
- Function requirements
- Function
General
The mirror heater heats the mirror glass of the outside mirrors. This allows ice or snow on the mirror glass to be defrosted and counteracts fogging of the mirror glass.
Function requirements
- Circuit 15R ON (except for pre-entry climate control for hybrid vehicles, electric vehicles)
- Engine running or drivetrain operational (for temperature-dependent switch-on).
Function
The mirror heater is switched on and off together with the rear window heater. It can also be switched on and off automatically depending on the outside or dew point temperature.
The dew point temperature is the temperature at which the water vapor in the outside air condenses. The mirror glass becomes fogged when its surface temperature is lower than the dew point temperature.
In hybrid vehicles and electric vehicles, the mirror heater can also be switched on and off as part of pre-entry climate control.
| Condition | Operating period | Additional information |
|---|---|---|
| Rear window heater active | According to the operating lifespan of the rear window heater | - |
| Pre-entry climate control activated (hybrid and electric vehicles) | According to the operating lifespan of pre-entry climate control | - |
| The dew point temperature is between 2 and 5°C below the outside temperature | Approx.10 min | If the value of the dew point temperature is implausible or not available, a substitute dew point value is used. |
| Outside temperature below 15°C | Approx.10 min | If the value of the outside temperature is implausible or not available, the mirror heater is switched on permanently. |
Should the mirror glass become fogged after the automatic actuation of the mirror heater is stopped, the mirror heater can be switched on again via the rear window heater.
If the on-board electrical system is in a state of undervoltage. the mirror heater is switched off via the consumer reduction feature of energy management.
| Function schematics | |||
| Function schematic, heat mirror glass of outside mirror | Model 118, 167, 177, 243, 247, 293 Model 213, 238, 257, 290 as of model year 2021 | PE88.79-P-2502-97A | |
| Model 192, 206, 214, 223, 232, 236, 254, 294, 295, 296, 297 | PE88.79-P-2502-97B | ||
| Model 464 | PE88.79-P-2502-97C | ||
| Further basic functions | |||
| Reduce consumers, basic function | GF54.10-P-1011A | ||
| Rear window heating, basic function | GF67.29-P-9900A | ||
| Front door control unit, basic function | GF72.29-P-9891A | ||
| Outside mirror, basic function | GF88.79-P-2014A |