Wiper and Washer Systems: Description and Operation

Wash-wipe equipment consists of one assembly for the windscreen, a separate assembly for each of the headlamps and another assembly for the rear window as an option on certain car model versions.

The wiper motors feature automatic parking and always return the wipers to the same position when they are switched off.

The windscreen wiper assembly includes a two-speed motor and a relay for intermittent operation of the wipers.

The headlamp wiper assembly consists of a separate motor for each wiper, installed underneath each - headlamp. The motors have-built-in overload protection (e.g. to avoid damage to the motor if the wiper blade freezes to the headlamp lens) consisting of a circuit-breaker actuated by a PTC resistor connected in series with the motor. A diode in the supply circuit prevents reverse current from the motor being supplied to the washer pump. The rear window wiper consists of a separate motor mounted on the tailgate.

The washer assembly consists of a fluid reservoir, on which is mounted a pump and level switch, and hoses and nozzles for the headlamps and windscreen and, on certain model versions, for the rear window.

The fluid reservoir holds about 4.2 litres (4.4 qts) and is mounted on the left-hand wheel housing (right-hand wheel housing on M92- models). The washer pump and level switch are situated in the lower part of the reservoir. The level switch causes a warning lamp in the main instrument display panel to light up when the fluid level drops below about 0.5 litres (0.5 qts).

The windscreen washer nozzles are mounted on the bonnet. The hose connected to the windscreen washer nozzles incorporates a non-return valve which prevents the hose from draining when not in use.

The headlamp washer nozzles are incorporated in the wiper arms. A delivery valve in the hose connected to these nozzles opens when the pressure has risen to 0.35 - 0.50 bar (5.1 - 7.2 psi). The purpose of this is to ensure that a certain amount of fluid is supplied to the windscreen before the headlamp washers start to operate.

The wash-wipe assembly is activated by means of a stalk switch on the right-hand side of the steering column below the steering wheel.