Rear window wiper system, function - GF82.30-P-2200FQ

MODEL 218.9 

Function requirements, general 

• Circuit 15R ON

The electronic ignition lock control unit (N73) transmits the circuit 15 status to the front SAM control unit with fuse and relay module (N10/1) over the interior CAN (CAN B).

Rear window wiper system in general 

The wiper system allows wiping and washing the rear window. The control logic for the rear window wiper system is stored in the front 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 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) reads in the switch position of the combination switch directly and sends this via chassis CAN (CAN E) (up to 28.2.13) or chassis CAN 1 (CAN E1) (as of 1.3.13) to the front SAM control unit. The front SAM control unit evaluates the switch position and sends the request "Switch on rear wiper" via interior CAN to the rear SAM control unit with fuse and relay module (N10/2). The rear SAM control unit then actuates the liftgate wiper motor (M6/4).

The actuation time is approx. t = 2 s (duration of wipe cycle). This is followed by a break for approx. t = 5 s. The active rear window intermittent wipe function is confirmed by the corresponding symbol lighting up in the instrument cluster (A1). The front SAM control unit then transmits the "Active rear window intermittent wipe" status to the instrument cluster via the interior CAN.

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 sends this via chassis CAN (up to 28.2.13) or chassis CAN 1 (as of 1.3.13) to the front 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 information on the selector lever position and the engaged gear range via drive train CAN (CAN C), CDI control unit (N3/9) (with diesel engine) or ME-SFI ME] control unit (N3/10) (with gasoline engine) and chassis CAN (up to 28.2.13) or chassis CAN 1 (as of 1.3.13) to the front SAM control unit.

The front SAM control unit reads in the data of the rain/light sensor via wiper/inside rearview mirror LIN (LIN2), evaluates all relevant information and sends corresponding requests via interior CAN to the rear SAM control unit. The rear SAM control unit 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 sends this via chassis CAN (up to 28.2.13) or chassis CAN 1 (as of 1.3.13) to the front SAM control unit. The front SAM control unit receives these and actuates the windshield washer system pump (M5/1) in the opposite direction to the "Windshield wash" function. Simultaneously the front SAM control unit transmits the request "Switch on rear window" to the rear SAM control unit via the interior CAN. The liftgate wiper motor is then actuated directly by the rear SAM control unit. 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 wipe operation 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 rear window wash 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 terminated, 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 rear window 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

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 an actuated manual or automatic wipe request. If a door or the liftgate is opened during wiping, the front SAM control unit interrupts the actuation of the liftgate wiper motor. Opening of the left front door is recognized by the status of the left front door rotary tumbler switch (A85s1) in the left front door lock (A85), which is read in by the left front door control unit (N69/1).

Opening of the right front door is recognized by the status of the right front door rotary tumbler switch (A85/1s1) in the right front door lock (A85/1), which is read in by the right front door control unit (N69/2). Opening of the liftgate is recognized by the status of the liftgate rotary tumbler switch (M14/7s1) in the trunk lid/liftgate central locking motor (M14/7), which is read in by the rear SAM control unit. The corresponding control unit transmit this information to the front SAM control unit via the interior CAN. The instrument cluster sends the vehicle speed to the front SAM control unit over the interior CAN. The front SAM control unit evaluates all of the relevant information and interrupts the actuation of the liftgate wiper motor via interior CAN and the rear SAM control unit.

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
• Rear wipe request
• Rear wash request
• Rotary tumbler switch closed and selector lever in position "D" or "R"
• Rotary tumbler switch closed and change from circuit 15C to circuit 15R

Final wipe:

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-2055-97XAA
Overview of system components, wiper system (WSA)	GF82.30-P-9997FQ