GM Service Manual Online
For 1990-2009 cars only

Wiper/Washer Circuit Operation

Whenever the ignition switch is in the ON or the START position, battery voltage is applied through the WIPER WASHER fuse to these components:

    • The front wiper/washer switch (in the combination switch)
    • The front wiper motor pawl and switch contacts

Washer Operation

When the front wiper/washer switch is pulled back, battery voltage is applied through the wash switch to the front washer pump. The front washer pump is grounded permanently grounded at G104 and will operate as long as the wash switch is engaged. In order to initiate wiper operation, the front wiper/washer switch must be turned to the LO or HI wiper positions.

Low Operation

With the front wiper/washer switch in the LO position, battery voltage is applied to the LOW side of the front wiper motor through these components:

    • The WIPER WASHER fuse
    • The low contacts of the front wiper/washer switch

Because the front wiper motor is permanently grounded at G109, 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 reach the PARK position.

High Operation

With the wiper/washer switch in the HIGH position, battery voltage is applied to the HIGH side of the front wiper motor through these components:

    • The WIPER WASHER fuse.
    • The HI contacts of the front wiper washer switch .

Because the front wiper motor is permanently grounded at G109, 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 reach the PARK position.

Pulse Wiper/Washer Circuit Operation

Whenever the ignition switch is in the ON or the START position, battery voltage is applied through the WIPER WASHER fuse to these components:

    • The front wiper/washer switch (in the combination switch)
    • The front wiper motor pawl and switch contacts

Washer Operation

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

    • The wash switch contacts
    • The intermittent controller

This action applies voltage to the low side of the front wiper motor. The front wiper motor is permanently grounded at G109. The motor will continue to operate in low as long as the wash switch is held in the ON position.

The front wiper motor pawl and switch will engage as the motor turns, and its contacts will remain closed until the wipers are in the PARK position. While the pawl and switch contacts are closed, voltage is applied to the LOW side of the front wiper motor through these components:

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

In this manner, the wipers will complete at least one sweep after the wash switch has been released.

Intermittent Operation

With the front wiper/washer switch in the INT position, battery voltage is applied through the WIPER WASHER fuse to the following components in the intermittent controller:

    • The coil of an electronic relay
    • A condenser

The condenser charges to voltage and the relay is energized as soon as power is applied. When the switch in the energized relay closes, current flows to the front wiper motor LOW side through the following components:

    • The YEL/BLU wire
    • The YEL/BLK
    • The front wiper/washer switch and intermittent controller
    • The BLU wire

This will cause the wipers to begin operating at low speed.

By the time the front wiper motor makes one complete sweep and the front wiper motor pawl and switch has engaged, the condenser in the intermittent controller has discharged. This discharge causes the intermittent controller relay coil to de-energize, and the switch in the relay to open. Current flow to the wipers is then cut off until the condenser is recharged. In this manner, intermittent wiper operation is achieved through the charging and discharging of the intermittent controller condenser.

Low Operation

With the front wiper/washer switch in the LO position, battery voltage is applied to the low side of the front wiper motor through these components:

    • The WIPER WASHER fuse
    • The low contacts of the front wiper/washer switch

Because the front wiper motor is permanently grounded at G109, the motor operates at low speed as long as the switch remains in this position. When the switch is placed in the OFF position, the pawl and switch assembly provides voltage to the motors until the wipers are in the PARK position.

High Operation

With the front wiper/washer switch in the HI position, battery voltage is applied to the high side of the front wiper motor through these components:

    • The WIPER WASHER fuse
    • The high contacts of the front wiper/washer switch

Because the front wiper motor is permanently grounded at G109, the motor operates at high speed as long as the switch remains in this position. When the switch is placed in the OFF position, the pawl and switch assembly provides voltage to the motors until the wipers are in the PARK position.

Rear Wiper/Washer Circuit Operation

Washer Operation

Whenever the ignition switch is in the ON or the START position, battery voltage is applied through the WIPER WASHER fuse to the rear wiper/washer switch. When the rear washer switch is pressed, battery voltage is applied through the closed contacts of the switch to these components:

    • The rear washer pump
    • The rear wiper motor

Because the rear washer pump is permanently grounded at G104, the pump continues to operate as long as the rear washer switch is held.

Rear Wiper Operation

Whenever the ignition switch is in the ON or the START position, battery voltage is applied through the WIPER WASHER fuse to the rear wiper/washer switch. When the rear washer switch is pressed, battery voltage is applied through the closed contacts of the switch to the rear wiper motor. Because the rear wiper pump is permanently grounded at G104, the pump continues to operate as long as the rear wiper/washer switch is in the ON position. The rear wiper motor also incorporates a pawl and switch assembly. This assembly allows the motor to receive battery voltage and complete the wipe cycle in the event that the following actions occur:

    • The rear wiper/washer switch is turned to the OFF position.
    • The wiper is not in the PARK (down) position.