GM Service Manual Online
For 1990-2009 cars only

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 module. The duration of the delay interval is determined by the delay resistor in the wiper/washer switch.

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

Pulse Operation

With the wiper switch in DELAY (pulse), battery voltage is applied to the wiper motor at terminal C through CKT 143. Voltage is also applied to terminal A through CKT 113 and terminal E through CKT 112.

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

Low-Speed Operation

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

The wiper motor module 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 C, D, and E of the wiper motor through CKT 143, 92, and 112. Voltage is also applied to terminal A through CKT 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 has battery voltage applied to terminal C only from CKT 143. The wiper motor continues to run until the park switch opens.

Washer Operation

When the washer switch is turned to ON, the battery voltage is applied to terminal A of the wiper motor through CKT 113. The washer switch also applies voltage to the washer pump through CKT 228. The wiper motor has voltage applied through the low-speed relay and operates at low speed for 2-4 wipes.

When the washer switch is held on, the wiper motor module will keep the washer pump on only as long as the washer switch is held on.

If the wipers had been in DELAY, LO, or HI, they would return to that operation after the wash cycle. If in the OFF position, they then return to park position after 2-4 wipes.

Mist Operation

When the wiper switch is moved to MIST and released, the wipers make one sweep at low speed and return to 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.