GM Service Manual Online
For 1990-2009 cars only

Pulse Operation

With the wiper switch in DELAY (pulse), battery voltage is applied to the wiper motor connector at terminal B through CKT 243. Voltage also is applied to terminal D 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 B through CKT 243, terminal E through CKT 112. Terminal D has a constant voltage of 1.3-1.5 volts applied through CKT 113.

High-Speed Operation

In the HI position of the wiper switch, battery voltage is applied to the wiper motor connector at terminal B through CKT 243, terminal C through CKT 92, terminal E through CKT 112. Terminal D has a constant voltage of 1.3-1.5 volts applied 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 the OFF position, the wiper motor assembly has battery voltage applied to terminal B only, from CKT 243. When the end of the sweep switch opens, the control circuit reverses the wiper motor, which activates the external depressed park mechanism. The wiper motor continues to run until the park position is reached.

Washer Operation

When the washer switch is turned to ON, the battery voltage is applied to terminal D of the wiper motor assembly through CKT 113. The washer switch also applies voltage to terminal A, which turns on the washer pump through CKT 228. The wiper motor operates at low speed for 2-4 wipes after the washer switch is released.

When the washer switch is held on, the wiper motor circuit board keeps the washer pump on only as long as the washer switch is held on.

If the wipers had been in delay, low or high, they would return to that operation after the wash cycle. If turned off, they then return to park position after 2-4 wipes.

Mist Operation

When the wiper switch is turned 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 LO speed.