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Rear window wiper system, function - GF82.30-P-2400FL

MODEL 212.2 

Function requirements, general 

IMPORTANT The electronic ignition switch control unit (N73) sends the status of circuit 15 to the front SAM control unit with fuse and relay module (N10/1) via interior CAN (CAN B).

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 front SAM control unit.

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

Function sequence for intermittent wipe on rear window 

The rear window intermittent wipe function is activated by actuating the 2nd ring on the multifunction 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 28.02.2013) or chassis CAN 1 (CAN E1) (as of 01.03.2013) to the front SAM control unit. The front SAM control unit evaluates the switch position and sends the "Rear window intermittent wipe" request (wiper speed) to rear SAM control unit with fuse and relay module (N10/2) via interior CAN. 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). To this end, the front SAM control unit sends the "Rear window wiper active" status via the interior CAN to the instrument cluster.

Additional function requirements for backup wiping 

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 reverse gear.

The liftgate wiper motor is actuated when the multifunction switch is set to the corresponding position:

With interval 1 or interval 2:

The rear window wiper runs synchronously with the windshield wiper. With continuous wipe 1 or continuous wipe 2:

The rear window wiper wipes continuously, but not synchronously with the windshield wiper.

When the rain/light sensor (B38/2) is active, the rear window wiper wipes with the wipe request activated 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 28.02.2013) or chassis CAN 1 (as of 01.03.2013) to the front SAM control unit.

The front SAM control unit reads in the data of the rain/light sensor via wiper/inside rear-view mirror LIN (LIN 2) and evaluates this.

The vehicle is shifted into reserve as follows:

Transmission 711, 716:

Engagement of the reverse gear is recognized by means of the status of the backup lamp switch (S16/2), which is read in directly by the front SAM control unit.

Transmission 722.6:

The request to engage gear range "R" is defined by the corresponding selector lever position. The electronic selector lever module control unit (N15/5) sends the selector lever position 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 28.02.2013) or chassis CAN 1 (as of 01.03.2013) to the front SAM control unit.

Transmission 722.9, 724.2, 725:

Gear range "R" is engaged by the fully integrated transmission control unit (Y3/8n4). The fully integrated transmission control unit then sends the status "Gear range R engaged" to the front SAM control unit via drive train CAN, CDI control unit or ME-SFI [ME] control unit and chassis CAN (up to 28.02.2013) or chassis CAN 1 (as of 01.03.2013).

The front SAM control unit evaluates all of the relevant information and transmits an appropriate requests via the 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 

Function sequence for rear window washing 

By actuating the 2nd 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 28.02.2013) or chassis CAN 1 (as of 01.03.2013) to the front SAM control unit. The front SAM control unit receives this 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 wiper" to the rear SAM control unit via the interior CAN. The rear SAM control unit then actuates the rear window wiper motor directly. 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 rear window wiper motor starts to wipe in continuous mode after a short delay.

IMPORTANT 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 wipe 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 

IMPORTANT The instrument cluster sends the vehicle speed to the front SAM control unit over the interior CAN. 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 28.02.2013) or chassis CAN 1 (as of 01.03.2013) to the front SAM control unit.

Function sequence for rear window wiper startup suppression 

The wiper startup suppression is intended to prevent the driver or front passenger from being sprayed with water from the rear window when getting in or out of the vehicle as the result of an initiated wipe operation. If a door or the liftgate is opened during wiping, the rear SAM control unit interrupts the actuation of the rear window 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 (M14/7s17) in the 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 front SAM control unit evaluates it and interrupts the actuation of the rear window wiper motor by sending a corresponding signal over the interior CAN, which is received by the rear SAM control unit.

Re-actuation of the rear window wiper motor takes place once the wiper startup suppression has been activated by one of the following events:

IMPORTANT Final wipe: If the rear window wiper is not in the parked position when the wipe function is switched off, a final wipe is made until the parked position is reached.

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