Windshield Washer, Function - GF82.35-P-3002LF

Model 217, 222 

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).

Washing windshield, general 

The washer fluid is pumped through the hoses to the wiper blades and sprayed directly in front of the wiper blades in accordance with the direction in which the wiper arms are moving. In other words, when the wiper arms move upwards, only the top part of the wiper blades is supplied with washer fluid.

In other words, when the wiper arms move downwards, only the lower part of the wiper blades is supplied with washer fluid. With its low washer fluid consumption, this optimizes the windshield cleaning process while also reducing the level of wiper blade wear.

Wiper blade 

Courtesy of MERCEDES-BENZ USA

The windshield wash function is comprised of the following subfunctions:

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

Washing function sequence 

The washing function is activated by pressing the combination switch (S4) in axial direction beyond the detent point.

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 receives the request and actuates the windshield washer system pump (M5/1) directly and the wiper motor (M6/1) via the rain/light sensor LIN (LIN B16).

Depending on the direction in which the wiper arms are moving, only the upper or the lower side of each wiper blade is supplied with washer fluid. This is implemented by reversing the polarity on the windshield washer system pump.

The wiper arm direction of movement is determined by the wiper motor. This sends corresponding information via the rain/light sensor LIN to the front SAM control unit.

During washing, wiping takes place with the wiper speed set on the combination switch or in stage "3".

The washing function is interrupted under the following conditions or aborted after t = 15 s:

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

Afterwiping function sequence 

The afterwiping function is activated as soon as the combination switch is no longer activated.

The number of afterwipe cycles depends on the combination switch actuation time.

On vehicles without CODE 874 (MAGIC VISION CONTROL, heated):

• Actuation time t < 200 ms: Afterwiping does not take place.
• Actuation time t < 1 s: A single afterwipe occurs.
• Actuation time t > 1 s: Three afterwipes occur.

On vehicles with CODE 874 (MAGIC VISION CONTROL, heated):

• Actuation time t < 200 ms: Afterwiping does not take place.
• Actuation time t < 2 s: A single afterwipe occurs.
• Actuation time t > 2 s: Two afterwipes occur.

The front SAM control unit sends the "Afterwipe active" status via the rain/light sensor LIN to the rain sensor (B38/2b1) in the rain/light sensor with additional functions (B38/2). Wiping requests from the rain sensor during afterwiping are ignored.

Afterwiping takes place with the wiper speed set on the combination switch. When the combination switch is in the rest position, afterwiping takes place with speed "3".

The afterwiping function is interrupted or aborted under the following conditions:

• Activation of the washer interruption function when the engine starts
• Wiper motor blockage detection
• Activating wash function
• Activating wipe/stop function

Function sequence for interrupting washing during engine start 

When the engine starts, the front SAM control unit blocks the actuation of the windshield washer system pump.

Any wiping procedure that has already started is terminated.

The engine start is recognized by the transmission of the status of circuit 50. The electronic ignition lock control unit transmits the status of circuit 50 to the front SAM control unit via the interior CAN.

Function sequence for wash stop 

The wash stop function prevents the windshield washer system pump from being actuated when the engine hood is open.

The status of the engine hood is monitored by the following components that are read in directly by the front SAM control unit:

• Right engine hood contact switch (S62/42)
• Left engine hood contact switch (S62/43)

If an open engine hood is recognized, the front SAM control unit interrupts the windshield washer system pump actuation.

If the engine hood is closed, the windshield washer system pump can be actuated again.

This is also possible if the engine hood is open and the vehicle speed exceeds v = 6 km/h.

The instrument cluster (A1) 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.

	Electrical function schematic for windshield washer		PE82.35-P-2051-97SEA
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