GM Service Manual Online
For 1990-2009 cars only

The windshield wiper/washer System consists of front and rear wipers, wagon only. The front and rear wipers are operative when the vehicle is in ACCESSORY or RUN. The front wipers have 4 different modes. The 4 modes are MIST, Intermittent, Low, and High. When the wipers are in the intermittent mode, there are 3 delay modes to chose from, commanded by the wiper switch through the body control module (BCM). There is one mode for the rear wipers. The rear wipers have an intermittent mode only, and the intermittent mode has 3 delay modes to chose from. The wipers are powered through the wiper switch except for the intermittent mode. The intermittent mode is controlled by the BCM. The front and rear wipers also have a washer function. By putting the wiper switch in the wash mode the front and rear wipers will spray washer fluid on the windshield and the wipers will then clean the windshield. The wipers will be controlled by the BCM.

High Operation - Front Wipers Only

In the high position, the windshield wiper switch supplies voltage to the high speed circuit of the windshield wiper motor. The windshield wiper motor will operate at high speed.

Intermittent Operation - Front and Rear Wipers

The body control module (BCM) controls the front and rear wipers, when the wipers are in the intermittent mode. When the BCM receives an input from the front or rear wipers switch, the BCM controls the input into the front or rear wiper relay. The BCM will energize the front or rear relay, commanding the wipers ON. There are 3 intermittent positions for the front or rear wipers. The intermittent switch, located in the wiper switch, sends inputs to the BCM indicating the speed the wipers should be in. Below is a table for the front and rear wipers indicating the time delay for each intermittent mode.

Front

Rear (with front wipers OFF)

Rear (with front wipers ON)

Front (INT)

Front (LOW)

Front (HIGH)

12 seconds

17 seconds

22 seconds

17 seconds

17 seconds

7 seconds

9 seconds

13 seconds

9 seconds

9 seconds

1 second

2 seconds

4 seconds

2 seconds

2 seconds

Low Operation - Front Wipers Only

In the Low position, the windshield wiper switch supplies voltage to the low/mist circuit of the windshield wiper motor. The windshield wiper motor will operate continuously at low speed.

Mist Operation - Front Wipers Only

In the MIST position, the windshield wipers switch supplies voltage to the low/mist circuit of the windshield wiper motor. The windshield wiper motor will operate at low speed.

The windshield wipers make one sweep at low speed and returns to the PARK position. If the windshield wiper/washer switch is held in MIST mode, the windshield wipers will continue to operate until the switch is released.

Park Position Operation

The wiper and rear wiper fuses, supplies voltage to signal circuit of the front and rear wiper motor, respectively. The signal will be pulled to voltage by the wiper motor while the windshield wiper motor is operating. When the windshield wiper motor has parked, the signal is at ground, front wiper motor, open, or rear wiper motor.

Wash Operation - Front and Rear Wipers

The front and rear Washer Systems use the same washer motor. When either the front or rear wiper is in the washer position, voltage will be supplied to one side of the washer motor, depending on whether it is front or rear, while the other side of the motor is grounded.

At this point, the windshield washer pump sprays solvent onto the windshield. When the front or rear washer is activated, the body control module (BCM) receives an input from the switch that it is activated. The BCM will control the wipers while in the WASH mode. The BCM will control either the front wiper relay or the rear wiper relay to turn on the wipers. The windshield wipers operate at low speed for 3 swipes and returns to the PARK position.