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Markings, upper wiper arm
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Marking, lower wiper arm
The drive for the windshield wipers is provided via two separate wiper drives with integrated electronics. Here, the left-hand unit (master) performs the control function via the right-hand unit (slave), whereby there is no difference between LHD vehicles and RHD vehicles. The left-hand wiper drive is connected via the control module subnetwork (LIN) bus with the generic electronic module (GEM) and therefore has one more electrical connection than the right-hand one. The GEM in turn provides the control functions for the left-hand wiper drive. The motors are each connected via a designated linkage to one of the wiper arms. They form a unit with the linkage which can only be replaced as a complete unit, as otherwise the park position of the wiper uinits cannot be correctly matched.
When replacing a wiper unit, make sure that only replacement parts are installed which have the same part number end digit as the wiper unit fitted to the vehicle. If no replacement part with the same end digit is available then both units should be replaced together.
When installing the wiper drives, note that they perform an automatic adjustment when they are switched on for the first time. It is important that the wiper arms are not mounted until after this automatic adjustment has been performed.
The wiper system can be set to a service position in order to install the wiper blades. The wipers are moved to this position by pressing the single wipe function within 3 seconds of switching the ignition off (pull the wiper lever down to do this). Then the wipers run to their upper reversing point, allowing the wiper blades to be replaced. Markings are provided on the windshield to help position the wiper arms during installation.
The wiper blade lengths are different on vehicles with a rain sensor compared to a vehicle without a rain sensor.
- left hand side: always 750 mm
- right hand side: 700 mm without rain sensor
- right hand side: 650 mm with rain sensor
On vehicles built up to 07/2006, the wiper system returns from the service position back to the park position after the ignition is switched on.
On vehicles built from 07/2006, in order to protect the wiper blades the wiper system does not automatically return to the park position after the ignition is switched on. The wiper system does not return to the park position until the wiper lever is moved to an arbitrary position.
Rear window wiper system
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Wash water level sensor
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Headlamp washer nozzles
Windshield wash/wipe system
The windshield wash/wipe system will only operate if the ignition switch is in the position "I" or "II".
Four wipe functions are available: "Single Wipe", "Speed 1", "Speed 2" and "Intermittent Wipe" or "Automatic Wipe" (depending on the specification of the vehicle)".
In "Speed 1" or "Speed 2" mode, the wipers are operating continuously at either normal speed or fast speed.
When the intermittent wipe mode is switched on the windshield wipers operate at normal speed with the following wiper delays:
- Wiper delay 1: 1 second
- Wiper delay 2: 3.5 seconds
- Wiper delay 3: 6 seconds
- Wiper delay 4: 9.5 seconds
- Wiper delay 5: 15.5 seconds
- Wiper delay 6: 22 seconds
NOTE:In the event of a failure, the default time for the wiper delay is 3.5 seconds.
When the windshield washer switch is operated washer fluid is sprayed onto the windshield. After a short delay designed to protect the wiper blades the wipers perform 2 or 3 wipes at low speed.
If when the windshield washer switch is activated the windshield wipers are switched off, a single wipe is performed 4 seconds after the wipers have returned to the home position after performing the 2 or 3 wipes.
If the wipers are set to intermittent wipe and the window washer switch is actuated, the wipes are only performed if no further wipe request has been selected via a shorter delay time within the 4-second delay time.
The post wipe function on the windshield ensures that any water remaining on the windshield after washing is wiped away. It is only required if the wipers are switched off or they are set to intermittent mode.
Rear window wash/wipe system
The rear window wash/wipe system will only operate if the ignition switch is in the position "II".
If the windshield wiper switch is in the "Off", "intermittent mode" or "automatic windshield wiper" (no wiping or low speed) position, then the wipe interval of the rear window wiper is 10 seconds.
If the switch for the rear window washer is pressed, then washer fluid is sprayed onto the rear window, and the wiper operates continuously at low speed. When the switch is released the rear window wiper performs another 2-3 wipes.
If reverse gear is engaged and the windshield wiper switch is in the normal, high speed or automatic windshield wiper (wiping at high speed) position, the rear window wiper will operate continuously until the gearshift lever is moved back to the neutral position.
Headlamp washer system
The headlamp washer system will start to operate when the windshield washer function is activated if, at the same time, the light switch is set to "dipped beam" or the headlamps have been switched on by the "automatic headlamps" function. The electrical control functions are performed by the headlamp washer relay, which is actuated by the GEM.
In order to prevent excessive water consumption, the headlamp washer system is only activated every fourth time the windshield wash/wipe switch is operated, provided the time elapsed since the first operation of the washer system does not exceed 10 minutes. If the windshield wash/wipe switch is activated again after 10 minutes the the headlamp washer system is activated and the time encoder is restarted.
If the wash water level warning lamp on the instrument cluster comes on because the wash water level in the washer reservoir is too low then the headlamp washer pump is no longer activated until the washer reservoir is topped up.
Rain sensor
CAUTION:The automatic windshield wipers must be switched off before the vehicle is driven into a car wash.
CAUTION:If the windshield is iced up, the wipers may only be activated by the rain sensor after the windshield has been completely defrosted.
NOTE:The rain sensor is an optical measuring instrument. Contamination such as oil, grease or dust impair its correct operation. Before switching on the automatic windshield wipers, the windshield must be clean in the area of the rain sensor.
The rain sensor (1) is integrated together with the light sensor in a housing which is mounted behind the rear view mirror on the windshield.
The LED emits a light beam of known intensity. The emitted beam emerges through the lens and is then reflected by the windshield.
The reflected light beam enters back through the lens and then reaches the photodiode. The corresponding value taken without moisture on the windshield is used as the reference value for the automatic calibration process.
Subsequent deviations from this value cause the windshield wipers to be switched on.
If rain lands on the windshield then the light reflected by the windshield has a lower intensity. This loss of intensity is registered by the photodiode and, proportionally to the loss of intensity, the module switches on the windshield wipers with the required wipe speed (in intermittent or continuous mode).
On vehicles built up to 07/2006 the wipers are only activated after switching on the automatic wipe function (wiper lever to intermittent position) when the water has been detected on the windshield by the rain sensor.
On vehicles built from 07/2006 a single confirmation wipe is performed after the automatic wipe function has been switched on.
It is not necessary to calibrate the rain sensor, as this has already been done at the factory.
The sensitivity of the rain sensor can be changed by adjusting the control resistor for the intermittent mode of the windshield wipers.
- Adjusting ring position - wide symbol: High sensitivity
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The wipers wipe even if only a small amount of water has been measured on the windshield.
- Adjusting ring position - narrow symbol: Low sensitivity
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The wipers only wipe if a large amount of water has been measured on the windshield.
