GM Service Manual Online
For 1990-2009 cars only

Pulse Operation

With the wiper switch in the 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.

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, and terminal D through CKT 113.

High Speed Operation

In the HI position of the wiper switch, battery voltage is applied at terminals B, C, and E of the wiper motor through circuits 243, 92, and 112. Voltage also is applied to terminal D 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 B only, from CKT 243. When the end-of-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 switch opens.

Washer Operation

When the washer switch is turned ON, battery voltage is applied to terminal D of the wiper motor through CKT 113. The washer switch also applies voltage to terminal A which turns on 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 sweeps after the washer switch is released.

When the washer switch is held in the ON position, the wiper motor circuitry keeps the washer pump on only as long as the washer switch is held ON.

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

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 continue to operate until the switch is released. The circuit operation is the same as that of low speed.