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Home >> Mercedes Benz >> 2021 >> Metris Van Cargo >> Repair and Diagnosis >> Electrical >> Motors, Switches, Relays >> Electrical System -- Body (1 Of 6) -- 447 Chassis >> Basic Knowledge >> Wiping Of Rear Window, Function - GF82.30-S-3007TRB

Wiping Of Rear Window, Function - GF82.30-S-3007TRB

Model 447.6/7 

with code W78 (Window in tailgate or hinged rear door with wipe/wash system) 

Model 448.7 

with code W78 (Window in tailgate or hinged rear door with wipe/wash system) 

Function requirements, general 

IMPORTANT The electronic ignition lock (EZS) control unit (N73) transmits the circuit 15 status over the interior CAN (CAN B) to the signal acquisition and actuation module (SAM) control unit (N10/1).

Rear window wiping, general 

The "Rear window wiping" function consists of the following partial functions:

Wiping function sequence 

The rear window wiping function on the combination switch (S4) has 4 positions:

The rear window washer switch in the combination switch is in the "zero position" in the non-actuated state.

Moving the rear window washer switch in the combination switch to the first position in the upwards direction selects the "intermittent wipe" position. In this position, the rear window wiper wipes at an interval defined by the combination switch. When the driver moves the switch in the upwards direction again, the "Washing as touch wiping, top" mode is activated. In this mode, the driver must hold the rear window washer switch in the combination switch in the upwards direction to actuate the windshield washer system pump (M5/4).

The steering column tube module (MRM) control unit (N80) directly reads in the switch position of the combination switch and transmits this via the chassis CAN (CAN E), electronic ignition lock (EZS) control unit, and interior CAN to the signal acquisition and actuation module (SAM) control unit.

The signal acquisition and actuation module (SAM) control unit actuates the following wiper motors via the rear window wiper relay (K40/11kB), depending on the equipment:

Wiping takes place with the wiper speed stored In the combination switch.

Function sequence for interrupting wiping during engine start 

The CDI control unit (N3/33) (with engine 651.9) or the ME-SFI [ME] control unit (N3/34) (with engine 274) or the CDI control unit (N3/36) (with engine 622) sends the "Engine start, request" signal via chassis CAN, electronic ignition lock (EZS) control unit and interior CAN to the signal acquisition and actuation module (SAM) control unit. The signal acquisition and actuation module (SAM) control unit blocks the actuation, depending on the vehicle equipment:

Any wiping procedure already started is interrupted while the engine is started and continues to run after the engine start.

Function sequence for wipe stop on vehicles with code W65 (Liftgate) 

If the liftgate is opened while the rear window is being wiped, actuation is canceled by the signal acquisition and actuation module (SAM) control unit. Any wiping procedure that has already started is terminated. The opening of the liftgate is detected by the Open liftgate, external operation (S52) switch. The signal acquisition and actuation module (SAM) control unit directly reads in the status. If the liftgate is closed or a vehicle speed of 3 km/h is exceeded, the liftgate wiper motor can be actuated again.

Function sequence for wipe stop on vehicles with code W50 (Two-wing rear-end door, 180 degrees, without window) or code W54 (Two-wing rear-end door, 270 degrees) 

If the rear-end doors are opened while the rear window is being wiped, actuation is canceled by the signal acquisition and actuation module (SAM) control unit. Any wiping procedure that has already started is terminated. The opening of the rear-end doors is detected by the left rear-end door rotary tumbler switch (S49/7) or right rear-end door rotary tumbler switch (S49/6). The signal acquisition and actuation module (SAM) control unit directly reads in the status. If the rear-end doors are closed, the left and right rear-end door wiper motors can be actuated again.

Intermittent wipe function sequence 

If the switch of the rear washing system in the combination switch is moved to the "Intermittent wipe" position, the combination switch transmits its status to the signal acquisition and actuation module (SAM) control unit via the steering column tube module (MRM) control unit, the chassis CAN, the electronic ignition lock (EZS) control unit and the interior CAN. The signal acquisition and actuation module (SAM) control unit then actuates one of the following wiper motors via the rear window wiper relay, depending on the equipment:

The "intermittent wipe" pause time for vehicles without CODE JF1 (Rain sensor) is approx. 5 s. For vehicles with CODE JF1 (Rain sensor), the pause time is dependent on the signal from the humidity sensor/light sensor/rain sensor/sun sensor (B38/3).

Function sequence for backup wiping 

When reverse gear is engaged and the "Windshield wiping" system is active, backup wiping is activated. First a complete wash cycle is carried out, i.e. the windshield washer system pump is actuated for t = 300 ms and the relevant rear window wiper makes 1 more wipe. Then the "Intermittent wiping" function of the "Rear window wiping" system is activated.

The CDI control unit receives the gear signal of the reverse gear, depending on the equipment:

The CDI control unit transmits the signal via the chassis CAN to the electronic ignition lock (EZS) control unit.

The electronic ignition lock (EZS) control unit transmits the signal via the chassis CAN to the steering column tube module (MRM) control unit. The steering column tube module (MRM) control unit then sends the signal to carry out backup wiping over the chassis CAN, the electronic ignition lock (EZS) control unit and the interior CAN to the signal acquisition and actuation module (SAM) control unit. The signal acquisition and actuation module (SAM) control unit then actuates the following components via the rear window wiper relay, depending on the equipment:

Afterwiping function sequence 

The after wiping function is activated as soon as the combination switch is no longer activated after a wash request.

The signal acquisition and actuation module (SAM) control unit transmits the "Washing procedure complete" signal via the interior CAN, the electronic ignition lock (EZS) control unit and the chassis CAN to the steering column tube module (MRM) control unit. The steering column tube module (MRM) control unit then transmits the "After-wipe request" signal via the chassis CAN, the electronic ignition lock (EZS) control unit and the interior CAN to the signal acquisition and actuation module (SAM) control unit. This then actuates one of the following wiper motors via the rear window wiper relay, depending on the vehicle equipment:

The operating time of the combination switch is not important in the rear window "After-wipe" function. A single after-wipe takes place when "Intermittent wiping" is complete.

The interval time is approx 5 s, like the "Intermittent wipe" function.

  Electrical function schematic for rear window wiper system Model 448.7 with code W78 (Window in tailgate or hinged rear door with wipe/wash system) PE82.30-S-2055-97VDB
    Model 447.6/7 with code W78 (Window in tailgate or hinged rear door with wipe/wash system) PE82.30-S-2055-97TRB
  Overview of system components, wiper system (WSA)   GF82.30-S-9997TRA 
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