(Rear Window Wiper System, Function - GF82.30-P-2400GR)

MODEL 166 

up to model year 2016 

Function requirements, general 

• Circuit 15R ON

The electronic ignition lock control unit (N73) transmits the status of circuit 15 via the interior CAN (CAN B) to the SAM control unit (N10).

Rear window wiper system, general 

The rear window wiper system allows wiping and washing the rear window. The control logic for the rear window wiper system is stored in the SAM control unit.

The rear window wiper system function is comprised of the following subfunctions:

• Function sequence for intermittent wipe on rear window 
• Function sequence for backup wiping 
• Function sequence for rear window washing 
• Function sequence for rear window afterwipe 
• Function sequence for rear window wiper startup suppression 
• Function sequence for final wipe of rear window 

Function sequence for intermittent wipe on rear window 

The rear window intermittent wipe function is activated by actuating the second ring on the combination switch (S4). The steering column tube module control unit (N80) directly reads in the switch position of the combination switch and sends this via chassis CAN 1 (CAN E1), electronic ignition lock control unit and interior CAN to the SAM control unit. The SAM control unit evaluates the switch position and actuates the liftgate wiper motor (M6/4) accordingly. The actuation time is approx. t = 2 s (duration of wipe cycle). This is then followed by a delay of approx. t = 5 s.

The activated rear window intermittent wipe function is confirmed by an illuminated symbol in the instrument cluster (A1). For this, the SAM control unit sends the "Rear window intermittent wipe active" status via interior CAN to the instrument cluster.

Additional function requirements for backup wiping 

• Rear window intermittent wipe function not active
• Windshield intermittent wipe function active (switch position of combination switch 1 or 2)

Function sequence for backup wiping 

When the windshield intermittent wipe function is activated, the backup wipe function is activated automatically when the vehicle is shifted into gear range "R".

Windshield wiper intermittent operation:

The rear window wiper runs synchronously with the windshield wiper.

Windshield wiper continuous wipe operation:

The rear window wiper wipes in continuous wipe mode, but not synchronously with the windshield wiper.

When the rain/light sensor (B38/2) is active, the rear window wiper operates with the wipe request triggered by the rain/light sensor. The steering column tube module control unit reads in the switch position of the combination switch directly and forwards it over the chassis CAN 1, electronic ignition lock control unit and interior CAN to the SAM control unit. Gear range "R" is engaged by the fully integrated transmission control unit (Y3/8n4). The fully integrated transmission control unit then sends the "Gear range R engaged" status over the drive train CAN (CAN C), CDI control unit (N3/9) (diesel engine) or the ME-SFI [ME] control unit (N3/10) (gasoline engine) and chassis CAN 1 (CAN E1) to the electronic ignition lock control unit. The electronic ignition lock control unit uses this to generate the "Reverse gear engaged" status and sends this information via interior CAN to the SAM control unit.

The SAM control unit reads in the data of the rain/light sensor via the roof LIN (LIN B13), evaluates all of the relevant information and then actuates the liftgate wiper motor accordingly.

Additional function requirements, rear window washing 

• Windshield wash not active

Function sequence for rear window washing 

By actuating the second ring on the combination switch, the rear window wash function is activated. The steering column tube module control unit reads in the switch position of the combination switch directly and forwards it over the chassis CAN 1, electronic ignition lock control unit and interior CAN to the SAM control unit. The SAM control unit receives this and actuates the windshield washer system pump (M5/1) in the opposite direction to the "windshield wash" function. At the same time, the SAM control unit actuates the liftgate wiper motor. The windshield washer system pump is actuated as long the "Rear window wash function" is requested by the multifunction switch. After the rear window wash function has been activated, the liftgate wiper motor starts to wipe in continuous mode after a short delay.

In order to prevent situations where the windshield washer system pump cannot be switched off because the combination switch is stuck, washing is aborted after a maximum of t = 15 s. The time and function are restarted after renewed actuation.

Function sequence for rear window afterwipe 

After the rear window wash function is completed (i.e. the windshield washer system pump is no longer actuated and the running wash cycle is ended), the rear window afterwipe function is activated. This is then followed by two afterwipe cycles in continuous mode. If the time for the request of the rear window wash function is less than the time for the delayed actuation of the liftgate wiper motor, only one afterwipe cycle is performed.

Additional function requirements for rear window wiper startup suppression 

• Vehicle speed v < 3 km/h
• Combination switch (second ring) in interval setting or backup wiping active

The instrument cluster sends the vehicle speed to the SAM control unit over the interior CAN.

Function sequence for rear window wiper startup suppression 

The wiper startup suppression should prevent people from being sprayed with water on the rear window when getting into or out of the vehicle or loading or unloading the load compartment as the result of an initiated wipe operation. The rear window wiper remains in park position despite a manually or automatically actuated wipe request. If a door or the liftgate is opened during wiping, the SAM control unit interrupts the actuation of the liftgate wiper motor.

The status of the left front door (open or closed) is sent by the left front door control unit (N69/1) via interior CAN to the SAM control unit.

The status of the right front door (open or closed) is sent by the right front door control unit (N69/2) via interior CAN to the SAM control unit.

The rear control unit (N10/8) transmits the status of the liftgate via interior CAN to the SAM control unit.

The SAM control unit evaluates all relevant information and interrupts actuation of the liftgate wiper motor.

The liftgate wiper motor is actuated again once the wiper startup suppression has been activated by one of the following events:

• Vehicle speed v > 3 km/h
• Activation of the rear window wiping function
• Activation of the rear window washing function
• Doors and liftgate closed and selector lever in position "D" or "R"
• Doors and liftgate closed and change from circuit 15C to circuit 15R

Function sequence for final wipe of rear window 

If the rear window wiper is not in the park position when the wipe function is switched off (omission of the function requirements), a final wipe is made until it moves to the park position.

	Electrical function schematic for rear window wiper system		PE82.30-P-2056-97NAA
	Overview of system components for windshield wiper system		GF82.30-P-9996GR