3

U641B

4773A–AUTO–11/03

Circuit Description

Interval Function, Pin 2

By closing the interval switch, S

internal current source (pin 3) which holds the capacitor C

off. As soon as there is a positive potential at the park switch (S

(see Figure 1 on page 1) charges the capacitor C

tion is finished, S

pause begins - the capacitor C

age at pin 3 is below the threshold of 2 V. Interval pause can be adjusted between 4 s to

20 s with the help of potentiometer R

cycle begins. Opening switch S

and current sources C and F are switched off.

Wipe/Wash (WIWA)

Operation, Pin 5

By closing the WIWA switch, S

the water on the windshield. During this function, the current source A is switched-off

which keeps the capacitor C

through the current source F. If (after a time interval of approximately 600 ms) the volt-

age at the capacitor is greater than 6.1 V, the relay is turned on as long as the switch

WIWA is closed.

The after-wiping time begins when the switch is open, the sources D and F are switched

off and the source E is activated. Source E discharges the capacitor until the voltage is

less than 2.2 V. The relay is off and the wiper-motor is supplied via the park switch until

the park position is reached. The after-wiping time is determined by the current source E

which can be regulated with the external resistor R

elapsed, the source A discharges the capacitor. The relay switch is independent of the

park switch S

Interval and WIWA

Functions

The interval function is interrupted immediately when the switch S

rent source A discharges the capacitor to a value of 2 V, afterwards, the normal wash

function starts.

Interval wiping starts immediately when the after-wipe time is over. The switching delays

are slightly shorter, because the capacitor is already charged to a value of 2 V.

The Wipe/Wash function is not interrupted when the interval switch S

interval function begins after the WIWA function has elapsed.