Rear Window Washer, Function - GF82.35-S-3001TRB

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 

• "Circuit 15R ON"

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

Rear window wash, general 

The "Rear window wash, general" function comprises the following subfunctions:

• Washing function sequence 
• Function sequence for interrupting washing during engine start 
• Function sequence for wash stop 

Washing function sequence 

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

• Washing as touch stage, top
• Intermittent wipe
• Zero position
• Washing as touch stage, down

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 "Washing as touch wiping, bottom" position can be selected by the driver by pressing the rear window washer switch in the combination switch downwards out of the "zero position". In this mode, the driver must hold the rear window washer switch in the combination switch in the downwards direction to actuate the windshield washer system pump.

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 then actuates the windshield washer system pump and the following components at the same time via the rear window wiper relay (K40/11kB), depending on the equipment:

• The liftgate wiper motor (M6/12) (with code W65 (Liftgate) and with code W78 (Window in liftgate or hinged rear door with wiper and washer system))
• The left rear-end door wiper motor (M6/10) and the right rear-end door wiper motor (M6/11) (with code W50 (Two-wing rear-end door, 180 degrees without window) and with code W78 (Window in liftgate or hinged rear door with wiper and washer system))
• The left rear-end door wiper motor and the right rear-end door wiper motor (with code W54 (Two-wing rear-end door, 270 degrees) and code W78 (Window in liftgate or hinged rear door with wiper and washer system))

During washing, wiping takes place with the wiper speed set on the combination switch.

The "wash" function has priority over the "backup wipe" function. This, in turn, has priority over the "intermittent wipe" function. The "intermittent wipe" function is not canceled out by the "wash" function.

Detailed information on the "backup wipe" position is provided in the "rear window wipe, function" subfunction.

The "washing" function is interrupted under the following conditions or after 15 s:

• Activation of the washer interruption function when the engine starts
• Activation of the "wash stop" function
• "Combination switch stuck" detection

Function sequence for interrupting washing 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:

• The liftgate wiper motor (with code W65 (Liftgate) and code W78 (Window in liftgate or hinged rear door with wiper and washer system))
• The left and right rear-end door wiper motors (with code W50 (Two-wing rear-end door, 180 degrees without window) and code W78 (Window in liftgate or hinged rear door with wiper and washer system))
• The left and right rear-end door wiper motors (with code W54 (Two-wing rear-end door, 270 degrees) and code W78 (Window in liftgate or hinged rear door with wiper and washer system))

The windshield washer system pump is not actuated.

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

Function sequence for wash stop on vehicles with CODE W65 (Liftgate) 

If the liftgate is opened while the rear window is being washed, the signal acquisition and actuation module (SAM) control unit cancels the actuation of the windshield washer system pump. 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, the windshield washer system pump can be actuated again.

Function sequence for wash 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 doors are opened while the rear window is being washed, the signal acquisition and actuation module (SAM) control unit cancels the actuation of the windshield washer system pump. 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 doors are closed, the windshield washer system pump can be actuated again.

Washer fluid supply 

The spray nozzles of the "Rear window wash" system are supplied with washer fluid via the windshield washer system pump. The windshield washer system pump is located at the washer fluid reservoir.

If the windshield washer system water level indicator switch (S42) sends the signal that the washer fluid reservoir is only 1/3 full, the "Check washer fluid level" message appears on the multifunction display (A1/1p13) of the instrument cluster (IC [KI]) control unit (A1/1). The signal acquisition and actuation module (SAM) control unit reads in the status of the windshield washer system washer fluid level indicator switch directly, and sends the signal over the interior CAN and instrument cluster (IC [KI]) control unit to the multifunction display.

When the washer fluid reservoir is empty, the "Washer fluid level" indicator lamp in the multifunction display of the instrument cluster (IC [KI]) control unit lights up continuously.

	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