GM Service Manual Online
For 1990-2009 cars only

Whenever the ignition switch is in the ON or the START position, battery voltage applies through the WIP fuse to the front wiper/washer switch and to the front wiper motor and switch contacts.

Washer Operation

When the front wiper/washer switch is pulled back, battery voltage applies through the wash switch contacts to the front washer pump. The front washer pump permanently grounds at G104 and will operate as long as the wash switch is engaged. In order to initiate wiper operation, battery voltage is also applied to the OFF contacts of the front wiper/washer switch through these components:

    • Wash switch contacts.
    • The Intermittent Controller IC.

This action applies voltage to the low side of the front wiper motor. The front wiper motor permanently grounds at G104. The motor will continue to operate in LO as long as the wash switch is engaged.

The front wiper motor pawl and switch will engage as the motor turns, and the contacts will remain closed until the wipers are in the park position. While the pawl and switch contacts are closed, voltage applies to the Low side of the front wiper motor through these components:

    • The WIP fuse.
    • The OFF contacts of the front wiper/washer switch.
    • The front wiper motor pawl and switch contacts.

This action allows the wipers to complete at least one sweep after the wash switch has been released.

Low Operation

With the front wiper/washer switch in the LO position, battery voltage applies through the following components:

    • The WIP fuse.
    • The LO contacts of the front wiper/washer switch.
    • The low side of the front wiper motor.

Since the front wiper motor permanently grounds at G104, the motor operates at low speed as long as the switch remains in the LO position. When the switch is placed in the OFF position, the pawl and switch assembly provides voltage to the motor until the wipers are in the park position.

High Operation

With the front wiper/washer switch in the HI position, battery voltage applies through the following components:

    • The WIP fuse.
    • The HI contacts of the front wiper/washer switch.
    • The high side of the front wiper motor.

Since the front wiper motor permanently grounds at G104, the motor operates at high speed as long as the switch remains in the HI position. When the switch is placed in the OFF position, the pawl and switch assembly provides voltage to the motor until the wipers are in the park position.

Pulse Operation

With the front wiper washer switch in the INT position, battery voltage applies to the following components:

    • The WIP fuse
    • The Intermittent Controller.
    • The INT Time switch.
    • The low side of the front wiper motor.

The length of the delay time between sweeps is controlled by the INT TIME switch setting. The INT TIME switch contains a variable resistor which is connected to the Intermittent Controller IC. The delay between sweeps is adjustable from SLOW (approximately 12 seconds) to FAST (approximately 4 seconds).