GM Service Manual Online
For 1990-2009 cars only

Wiper Operation

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 end of the sweep (inner wipe) position.

Pulse Operation

With the wiper switch in the DELAY (pulse) position, battery voltage is applied to the wiper motor connector at terminal B through circuit 143. Voltage is also applied to terminal D through circuit 113 and terminal E through circuit 112.

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. For fixed-pulse systems, the length of delay time between sweeps is non-adjustable.

Low-Speed Operation

In the LO position of the wiper switch, battery voltage is applied to the wiper motor connector at terminal B through circuit 143, terminal E through circuit 112, and terminal D through circuit 113.

The circuit board supplies power to the wiper motor which runs continuously through the low-speed relay.

High-Speed Operation

In the HI position of the wiper switch, battery voltage is applied at terminal B, C, and E of the wiper motor assembly through circuits 143, 92, and 112. Voltage is also applied to terminal D through circuit 113.

Park Position Operation

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 terminal B only, from circuit 143. The wiper motor continues to run until the internal motor park switch opens.

Washer Operation

When the washer switch is turned to ON, battery voltage is applied to terminal D of the wiper motor assembly through circuit 113. The washer switch also applies voltage to the washer pump through circuit 228. 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.

Mist Operation

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.