Rear Window Wiper System, Function - GF82.30-P-2400RF

Model 205.2, 253

Function requirements, general

Circuit 15R ON

The electronic ignition lock control unit (N73) sends the status of circuit 15 via interior CAN (CAN B) to the front SAM control unit (N10/6).

Rear window wiper system, general

The control logic of the rear window windshield wiper system is stored in the front SAM control unit.

The rear window wiper system function consists of the following subfunctions:

Intermittent wipe function sequence
Function sequence for backup wiping
Washing function sequence
Wiper start suppression function sequence

Intermittent wipe function sequence

The intermittent wipe function is activated by operating 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 it to the front SAM control unit via the chassis FlexRay (Flex E), electronic ignition lock control unit and interior CAN. The front SAM control unit evaluates the switch position and sends the request "Switch on rear window wiper" (wiper speed) via interior CAN to the rear SAM control unit (N10/8). The rear SAM control unit then actuates the liftgate wiper motor (M6/4) directly.

The actuation time is approx. t = 2 s (duration of a wipe cycle). This is followed by a pause of approx. t = 5 s.

The active rear window intermittent wipe function is confirmed by the illumination of a corresponding symbol in the multifunction display (A1p13) of the instrument cluster (A1). The front SAM control unit sends the "Rear window wiper running" status for this via interior CAN, electronic ignition lock control unit and user interface CAN (CAN HMI) to the instrument cluster.

When ending the intermittent wipe function, the rear window windshield wiper is moved to the park position.

Additional function requirements for backup wiping

Windshield intermittent wipe function activated or
Windshield continuous wipe function active
Rear window wipe function not active

When the windshield intermittent wipe function is active, the liftgate wiper motor is actuated depending on the request from the rain sensor (B38/2b1) in the rain/light sensor with additional functions (B38/2). The front SAM control unit reads in the wipe request from the rain/light sensor with additional functions over the rain/light sensor LIN (LIN B16).

Function sequence for backup wiping

When engaging reverse gear, the reversing wipe is automatically activated.

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 windshield wiper runs synchronously with the windshield wipers.

With continuous wipe 1 or continuous wipe 2:

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

The vehicle is shifted into reserve as follows:

Vehicles with transmission 716:

The engaged reverse gear is recognized via the manual transmission main shifter shaft position sensor (B79/3). The CDI control unit (N3/9) (diesel engine), or the ME-SFI [ME] control unit (N3/10) (gasoline engine) reads in the signals of the manual transmission main shifter shaft position sensor directly and sends the signal "Reverse gear engaged" via drive CAN (CAN C1), powertrain control unit (N127), and suspension FlexRay to the electronic ignition lock control unit.

Vehicles with transmission 722, 724, 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 of the gear range via drive train CAN, powertrain control unit and the chassis FlexRay to the electronic ignition lock control unit.

Model 253.99:

The powertrain control unit transmits the status of the reverse gear or drive range via suspension FlexRay to the electronic ignition lock control unit.

The electronic ignition lock control unit uses the incoming information to generate the "Reverse gear engaged" status that is independent of the transmission variant and sends this via interior CAN to the front SAM control unit.

The front SAM control unit evaluates the status and sends the request "Switch on rear window wiper" via interior CAN to the rear SAM control unit. The rear SAM control unit then actuates the liftgate wiper motor accordingly.

When ending the reversing wipe function, the rear window windshield wiper is moved to the park position.

Additional function requirements for wash

Windshield wash not active

Washing function sequence

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 it via chassis FlexRay, the electronic ignition lock control unit and interior CAN to the front SAM control unit. The front SAM control unit actuates the windshield wiper system pump (M5/1) in the opposite direction of the windshield washing function and sends the "Switch on rear window wiper" request via interior CAN to the rear SAM control unit. The rear SAM control unit then 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 activating the rear window wipe function, the liftgate wiper motor starts to wipe after a delay in continuous wipe mode.

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.

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 extended wiping function is activated.

There are 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, there is only one afterwipe.

Additional function requirements for wiper start 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 front SAM control unit over the user interface CAN (CAN HMI), electronic ignition lock control unit and interior CAN.

Wiper start suppression function sequence

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 front door or the liftgate is opened during wiping, the front SAM control unit interrupts actuation of the liftgate wiper motor.

The 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). The left front door control unit (N69/1) reads in the status of the left front door rotary tumbler switch directly and sends it to the front SAM control unit via interior CAN.

The 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). The right front door control unit (N69/2) reads in the status of the right front door rotary tumbler switch directly and sends this via interior CAN to the front SAM control unit.

The opening of the liftgate is detected via the status of the trunk lid/liftgate lock main catch switch (A85/5s1) in the trunk lid/liftgate lock (A85/5). The rear SAM control unit reads in the status of the trunk lid/liftgate lock main catch switch directly and sends this via interior CAN to the front SAM control unit.

The front SAM control unit evaluates all relevant signals and interrupts the output of the "Switch on rear window wiper" request.

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
Doors and liftgate closed and gear range "D" or "R" engaged (transmission 722, 724, 725)
Doors and liftgate closed and clutch pedal switch (S40/3) (transmission 716) actuated:
Clutch actuation is recognized by the clutch pedal switch (transmission 716). The CDI control unit (diesel engine), or the ME-SFI [ME] control unit (gasoline engine) directly reads in the status of the clutch pedal switch and sends this via drive train CAN, powertrain control unit, chassis FlexRay, electronic ignition lock control unit and the interior CAN to the front SAM control unit.
Doors and liftgate closed and change from circuit 15C to circuit 15R

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