Wiper and Washer Systems: Description and Operation
WIPERS AND WASHERSAll functions are initiated by means of a wiper/washer switch which is operated by the wiper lever on the right-hand side of the steering column.
The wiper and washer circuits are protected by fuse 56 (20A) in the central junction box (CJB).
Windshield wiper
The windshield wiper system comprises the following parts:
- Windshield wiper arm (two)
- Windshield wiper motor on the air cowl trim panel
- Windshield wiper linkage
- Windshield wiper blade (two)
- Wiper relay, in the central junction box (CJB)
- Generic electronic module (GEM)
- Multi-function switch, comprising of
- Wiper switch
- Washer switch (pressure switch) and
- Delay control switch (rotary switch, depending on model)
Windshield wiper functions
The windshield wiper motor has two speeds and a limit switch for the parked position. It is controlled by the wiper/washer switch on the steering column through the wiper relay and the GEM.
After switching the ignition to the ON position, the following five wiper functions are available:
- Off
- Once
- Slow
- Fast
- Intermittent
Wiper lever in the OFF position
If the wiper lever is switched from another position to OFF, the windshield wiper motor continues to operate at a slow speed until the parked position is reached and then stops. This is effected by a second circuit via the limit switch. Power is thereby supplied to the windshield wiper motor after it is switched off until the limit switch cuts off the flow of current through the wiper relay (normally closed contact) and the wiper/washer switch to the windshield wiper motor.
Wiper lever in the ONCE position
Push the wiper lever downwards and release. It returns automatically to the OFF position. The windshield wiper motor performs one wipe cycle at a slow speed. The current flows through the wiper/washer switch to the windshield wiper motor.
Wiper lever in the SLOW position
Push the wiper lever two steps upwards. The windshield wiper motor operates at a slow speed. The current flows through the wiper/washer switch to the windshield wiper motor.
Wiper lever in the FAST position
Push the wiper lever three steps upwards. The windshield wiper motor operates at fast speed. The current flows through the wiper/washer switch to the windshield wiper motor.
Wiper lever in the INTERMITTENT position
Push the wiper lever one step upwards. The windshield wiper motor performs single wiping movements at a slow speed with pauses between them. Depending on the model, the wiping time interval is either set at the fixed setting of 9 seconds or one of six steps can be selected by turning the knob at the end of the wiper lever (position 1 = short interval. Position 6 = long interval).
The wiper/washer switch sends a 12 V signal to the GEM through the normally closed contact for the washer system switch that activates the wiper relay periodically, at nine second intervals or according to the intermittent wipe time selected (depends on the model variant). The current flow to the windshield wiper motor is established through the wiper relay (normally open contact) and the wiper/washer switch.
Windshield washer
WARNING: Washer fluid contains the poisonous substance methanol. Observe the safety rules. Failure to follow this instruction may result in personal injury.
The windshield washer comprises the following parts:
- Windshield washer reservoir, below the front left-hand fender
- Washer pump, on the outside of the washer reservoir
- Two washer nozzles on the hood/bonnet, adjustable.
There are two possible functions, and these depend on how the wipers are operating.
Wiper lever in the OFF or INTERMITTENT position
The wiper and the washer pump operate for as long as the wiper lever is pulled towards the steering wheel. Releasing the wiper lever causes the washer pump to be switched off immediately. The windshield wipers perform two to three more cycles before they adopt the intermittent operation again (INTERMITTENT position) or stop in the parked position (OFF position).
Wiper lever in the SLOW or FAST position
The washer operates together with the wipers for as long as the wiper lever is pulled towards the steering wheel. The current flows from the wiper/washer switch through the washer pump to the GEM and the washer switch. The washer switch in the active state makes the ground connection.
Rear window wiper
The rear window wiper system comprises the following parts:
- Rear window wiper motor
- Rear window wiper arm
- Rear window wiper blade
- Wiper delay relay, below the front right-hand crash padding
- One nozzle
Wipers and rear window washer
To switch it on, push the wiper lever towards the instrument panel. The washer operates for as long as the lever is pushed. When it is released, it returns automatically to the rest position. The washing water for the rear window washer is taken from the same reservoir (see Windshield washer) and also pumped by the washer pump.
In this case the washer pump operates in the opposite direction of rotation to the direction for washing the windshield.
The current flows from the central junction box through the washer pump to the washer switch. The washer switch in the active state makes the ground connection.
Washer fluid warning light (if equipped)
This consists of the following components:
- Washer fluid warning light (in the instrument panel)
- Switch in the washer reservoir
- Auxiliary warning system module (in the center of the instrument panel)
The warning light indicates that the washer reservoir is only a quarter full. A float-operated switch in the washer reservoir acts as a sensor. If there is a sufficient supply of fluid, the switch connects a digital input of the auxiliary warning system module to ground. It opens when the fluid level has dropped to a quarter full.