SRA Headlight Washer System

SRA Headlight Washer System

To clean the headlights, water is sprayed at high pressure out of pop-up jets onto the headlights. The pop-up jets are moved upwards by water pressure and are adjusted in such a way that the headlights are cleaned thoroughly even at high vehicle speeds.

Brief description of components

Wiper module
The wiper module is part of the wiper drive and is permanently connected to the wiper motor. The wiper module contains the electronics for controlling the windshield wiper, the washer pump and the wet arm heater. The control system for the pop-up jets and the SRA pump is also integrated. The wiper module is connected to the K-CAN SYSTEM data bus.

SZL steering column switching center
The steering column switching center registers the signals of the switches and sensors installed in the steering wheel. It also controls all the components located on the steering wheel and the steering column. Information is received and sent via the BYTEFLIGHT data bus.

The wiper switch is connected to the steering column switch center.

Wiper switch
The wiper stages are activated by means of the wiper switch. Pulling the wiper switch against the direction of travel activates the washer pump for the windshield and the SRA headlight washer system function.

There is also a button on the wiper switch that can be used to activate wiping operation via rain sensor (special equipment).

The function of the SRA headlight washer system is not affected by the rain sensor function.

The switch positions of the wiper switch are transferred from the steering column switching center via the BYTEFLIGHT and K-CAN SYSTEM data buses to the wiper module.

SRA pump
The SRA pump pumps the water from the washer fluid reservoir to the pop-up jets. It is activated directly by the wiper module.

Central Gateway Module (ZGM)
The central gateway module links the data buses
- BYTEFLIGHT
- K-CAN SYSTEM
- PT-CAN
- Diagnostic bus

Main functions

Headlight washing
The SRA headlight washer system is operational from terminal R ON. When the ignition and the parking light are switched on, a cleaning operation of the headlights is always initiated when the washer pump is activated for the first time. One cleaning operation consists of two spray cycles. The cleaning operation is automatically initiated
- every fifth triggering of a washing operation with the windshield washer pump when
- the parking light is switched on and
- the function "With SRA" is encoded.

The cleaning operation is controlled by the wiper module in the following sequence:
- The pop-up jets are popped up.
- The SRA pump is activated.
- Water is sprayed through the pop-up jets onto the headlight glass.

Repeat lockout
Following a spray cycle, no further spray cycles can be triggered within a disable period of five minutes.

The anti-repeat circuit and the counter for the number of cleaning operations is reset by terminal R OFF.

If the need to refill the washer fluid reservoir is indicated to the control system via the K-CAN SYSTEM data bus, an SRA cleaning cycle is only initiated every eighth triggering of a washing operation.

Load deactivation
If high battery load with priority 5 or 6 is signaled to the wiper module via the K-CAN SYSTEM data bus, activation of the SRA is delayed until every eighth triggering of a washing operation.

Safety functions

Interlock
The washer pump and the SRA pump are also disabled when the wiper interlock is activated by the wiper control system. The pumps are enabled when the windshield wiper can be reactivated by means of the wiper switch.