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

MODEL 453.0/3

Function requirement

Circuit 15 ON (signal from ignition lock (S2) via the vehicle interior fuse and relay module (F2))

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 center SAM control unit (N10/10). The center SAM control unit actuates the liftgate wiper motor (M6/4) via a direct electrical line. The windshield wiper is moved back to the rest position after the wiping operation. The liftgate wiper motor is actuated by the center SAM control unit until it has reached the rest position. The rest position is detected by the center SAM control unit using a contact switch that is integrated in the liftgate wiper motor.

The rear window wiper system function consists 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 intermittent wipe on rear window

The rear window intermittent wipe function is activated by moving the outer ring of the windshield wiper system switch (S4/4) to the first detent. The center SAM control unit reads in the position of the windshield wiper system switch directly, evaluates the switch position and actuates the liftgate wiper motor directly. The pause between two wiping cycles (interval pause) is speed-dependent and is:

v ≤ 40 km/h approx. t = 7 s
v ≤ 70 km/h approx. t = 5 s
v ≥ 70 km/h approx. t = 3 s

The center SAM control unit receives the vehicle speed via the interior CAN (CAN B) from the Electronic Stability Program control unit (N30/4).

Function sequence for backup wiping

Additional function requirements for backup wiping function sequence:

Function activated in instrument cluster (A1) and in center SAM control unit via diagnosis
Function activated via the Smart Radio Multimedia Navigator (A40/3) (only vehicles with code 535 (smart media system))
Windshield wiping switched on (intermittent, continuous wipe or automatic wiping in vehicles with code V54 (Rain/light sensor))

When the windshield intermittent wipe function is activated, the backup wipe function is activated automatically when the vehicle is shifted into reverse gear. The rear window wiper wipes in intermittent operation with a delay of t = 5 s between two wipe cycles (interval pause). Selection of reverse gear is detected by the center SAM control unit as follows via a direct line:

In vehicles with code 410 (5-speed manual transmission) via the backup light activation/idle recognition switch (S29/5)
In vehicles with automatic transmission (code 429 (twinamic)) or in model 453.091/391 via the signal of a direct electrical line from the electronic selector lever module control unit (N15/5)
The information "Windshield wiping active" is received by the center SAM control unit via the position of the windshield wiper system switch. In vehicles with code V54 (Rain/light sensor), the signal of the rain/light sensor (B38/2) is also evaluated so that the backup wiping function is only carried out if a wipe request is actually present during automatic windshield wiping. The status of the rain/light sensor is received by the center SAM control unit via the interior CAN from the driver-side SAM control unit (N10/11). The center SAM control unit evaluates all of these input signals and then actuates the liftgate wiper motor. The "Backup wiping" function has priority over the "Rear window intermittent wipe" function, and is therefore also carried out if the "Rear window intermittent wipe" function has also been activated.

Function sequence for rear window washing

Additional function requirements for rear window washing function sequence:

Windshield wash not active

The rear window washing function is activated by turning and holding the outer ring of the windshield wiper system switch in the washing position for t > 0.5 s. The windshield washer system pump (M5/1) is actuated in the opposite direction to the windshield washing function, and the washing water is pumped to the spray nozzle of the rear-end door for the length of time that the windshield washer system switch is held in the washing position. In order to do this, the windshield washer system pump is actuated via a direct line by the windshield wiper system switch for the length of time that the outer ring of the windshield wiper system switch is held. In parallel to this, the center SAM control unit reads in the position of the windshield wiper system switch and actuates the liftgate wiper motor at the same time. The "Wash rear window" function has top priority and is therefore also carried out if the "Rear window intermittent wipe" function or the "Backup wiping" function has also been activated.

Function sequence for rear window afterwipe

After releasing the windshield wiper system switch and therefore ending the rear window washing function (i.e. the windshield washer system pump is no longer actuated and the current wash cycle has completed), the rear window afterwipe function is activated. There are two afterwipe cycles in continuous mode. After a pause of t = 3 s another after-wipe takes place (Drop-Wipe). If another request for "Wash rear window" is received during the after-wipe, the rear window after-wipe function sequence is interrupted and the "Wash rear window" function sequence is carried out again.

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