General Information

Windshield Wiping/Washing







The windshield wiper/washer system on the E38 is similar in operation to previous ZKE systems The wiper/washer system consists of the GM III, wiper switch, two relays, the wiper motor, the washer pump and the headlight washer pump I module.

All wiping/washing functions are controlled from the stalk switch. The system has four wiping stages and tour interval wiping speeds.

The wiping stages include:

The functions of single wipe, intermittent wipe, slow and fast wipe are coded input signals to the GM III through two circuits. The GM recognizes from the combination of high/low signals which wiping function to activate.

The intermittent wiping time inputs are provided by a potentiometer mounted in the stalk switch.












Single Wipe
Single wipe is activated by depressing the wiper stalk switch down. When depressed momentarily, the wipers will make a single pass across the windshield.

Intermittent Wipe
The wiper intervals are dependent on the road speed signal. The interval time will vary from 26 seconds with no road speed to 2 seconds at high speeds depending on the intermittent setting selected.

A potentiometer; connected to the knurled wheel, on the wiper stalk provides the input for the basic wiping interval. The voltage value of the potentiometer varies from 1 .49V to 3.5 V from position one to position four interval wipe.

Slow/Fast
The wiping speed in stage I and stage II are also road speed dependent. Stage I follows the previous logic where stage I switches to intermittent when the vehicle is stopped. Additionally, stage II now switches to stage I when the vehicle is stopped.

To protect the wiper motor from excessive loads, the return contact (parking contact) is used as an input signal for wiper operation. If the return contact signal is not present for 16 seconds, indicating a blocked wiper arm, the wipers will switch off.

The GM III receives the vehicle speed signal over the K-Bus. If the signal is defective or missing, the GM will use the Servotronic input speed "A" signal for operation.

Windshield/Headlight Washing







Windshield washing is activated directly from the GM III based on the ground input from the stalk control.

Headlight washing is activated as follows:
- The general module receives a headlight on signal over the K-Bus.
- With this signal present and a wash request from the wiper washer switch, the GM III signals the headlight wash relay module
- The headlight wash relay module activates the separate pump for headlight cleaning.

Windshield Wiper Blade Service
Swinging the wiper arms away from the windshield in not possible with the wipers parked. To access the wiper arms for cleaning or wiper blade replacement requires the following:

- With ignition switch in KL 15 switch the wipers on in the intermittent wipe mode.
- Switch the ignition off when the wiper arms are in the up position.