GM Service Manual Online
For 1990-2009 cars only

Wiper/Washer System

In addition to the features of a conventional (non-pulse) wiper system (mist, low, and high speeds), the pulse-type windshield wiper/washer system includes an operating mode in which the wipers make single sweeps with a time interval between sweeps. The time interval is controlled by a solid-state timer in the wiper motor cover assembly. The duration of the delay interval is determined by the delay resistor in the wiper/washer switch assembly.

When the wiper switch is turned off, the wiper motor returns the wipers to the park position.

Pulse Description

With the ignition in the ACC or RUN position, battery voltage is applied to the wiper motor module connector cavity C and the windshield wiper / washer switch through CKT 143 (YEL). With the wiper switch in the DELAY (pulse) position, voltage is also applied to the windshield wiper motor module connector cavity E through CKT 96 (BRN)

For variable-pulse systems, the length of delay time between sweeps is controlled by the variable-pulse delay resistor. Delay is adjustable from 1-22 seconds, nominally.

Mist Description

When the wiper switch is moved to MIST and released, the wipers make one sweep at low speed and return to the park position. If the wiper switch is held in MIST, the wipers will continue to operate until the switch is released. The circuit operation is the same as that of low speed.

Low-Speed Description

In the LO position of the wiper switch, voltage is applied, through a fixed resistor in the switch, to the wiper motor connector cavity E through CKT 96 (BRN).

The internal circuit board supplies power to the wiper motor and ground is supplied through CKT 150 (BLK) from G200 and the motor runs continuously through the low-speed relay.

High-Speed Description

In the HI position of the wiper switch, battery voltage is applied at cavity D of the wiper motor assembly through CKT 92 (PPL).

The internal circuit board supplies power to the wiper motor and ground is supplied through CKT 150 (BLK) from G200 and the motor runs continuously in hi-speed.

Park Position Description

When turned OFF from any position, the wipers complete the last sweep and park. When the wiper switch is in OFF, the wiper motor assembly has battery voltage applied to cavity C only, from CKT 143 (YEL). The wiper motor continues to run until the internal motor park switch opens.

Washer Description

When the washer switch is turned to ON, battery voltage is applied to cavity E of the wiper motor assembly through CKT 96 (BRN). The solid state circuit applies voltage to the washer pump connector cavity A through CKT 228 (RED). The wiper motor has voltage applied through the low-speed relay and operates at low or high speed for 3-5 wipes.

If the wipers had been in DELAY, LO, or HI, they would return to that operation after the wash cycle. If they had been in the OFF position, they would then return to the park position after 3-5 wipes.