Wiper and Washer Systems: Description and Operation

Windshield wiper operation is controlled by a dash or steering column mounted switch. The wiper feed circuit is protected by a fuse which is located in the fuse block on most models, or in an Inline fuse holder on some models with pulse wipers. A circuit breaker, integral with the motor brush holder, protects the motor against overload. Pulse wipers, available on most models, use a variable resistor, a pulse control module, and/or a modified wiper motor to provide a delay wipe mode.


Standard (Non-Pulse) Wiper Operation

When the wiper switch is on low, battery voltage is applied to the wiper motor through the blue wire. When the wiper switch is in high, battery voltage is applied directly to motor through the blue/red wire to the high speed brushes.
When the wiper switch is turned off, the run/park switch in the wiper motor is still in the Run position. Voltage is still applied to the wiper motor at the low speed brushes through the run/park switch, blue/white and blue wires.

Fig. 15 Wiring Diagram, W/pulse (Metro):

Pulse Wiper Operation

When the wiper switch is in the delay position, a shunt is applied to two of the inputs at the pulse wiper relay, by section A of wiper switch Fig. 15, to start the pulse operation. The pulse wiper relay momentarily supplies battery voltage to section C of wiper switch Fig. 15, to run the wiper motor. The wiper blades make one sweep and reach park, the park/run switch opens. The wiper blades remain in park until the pulse wiper relay supplies battery voltage to start another sweep. The delay time between sweeps is determined by circuits in the pulse wiper relay.