Wiper/Washer System Circuit Description (Pulse)
Wiper/Washer System Circuit Description (Pulse)
In addition to the features of a conventional (non-pulse) wiper system (MIST, LO, and HI speeds), the pulse wiper/washer system includes an operating mode in which the wipers make single strokes with an adjustable time interval between strokes.
A solid-state delay/speed/wash control in the windshield wiper motor controls the time interval.
The pulse resistance rheostat in the windshield wiper switch determines the duration of the time interval.
Low Speed
In the LO position, the windshield wiper switch supplies voltage to CKT 112 (GRY) and the delay/speed/wash control.
The delay/speed/wash control provides ground to the park/run relay inside the windshield wiper motor, which is then energized.
The park/run relay supplies voltage to the brushes of the wiper motor.
The wipers run at low speed until turned off.
High Speed
With the wiper/washer switch in the HI position, battery voltage is supplied from CKT 92 (PPL) directly to a second armature terminal of the wiper motor.
The wipers run at high speed.
When the wiper/washer switch is turned to the OFF position, the wipers complete one last sweep at low speed then PARK.
Park
When the wipers are turned off, the wiper motor runs at low speed until the wiper blades reach the PARK position. Then, the park/run relay (within the solid state module) opens stopping the wiper motor immediately.
The wiper blades remain in the PARK position.
Mist
When the control is moved to MIST and released, the wipers make one sweep at low speed and return to the PARK position.
The circuit operation is the same as low speed.
Pulse
With the wiper/washer switch in the PULSE position, voltage is supplied to CKT 112 (GRY), the wiper motor module, and the solid-state control board.
Voltage is supplied to the park/run relay coil, which is momentarily grounded by the delay/speed/wash control circuit, and the relay closes.
In order to run the wiper motor at LO speed, battery voltage is supplied by CKT 143 (YEL) through the closed contacts of the relay.
The relay remains energized as long as the contacts of the park/run switch remain closed. When the wiper blades reach the PARK position, the park/run switch opens, de-energizing the park/run relay.
The wiper blades remain in the PARK position until the control board grounds the park/run relay coil in order to start another sweep.
The delay resistors control the delay time between sweeps.
The delay can be adjusted from 0 to 43 seconds.
Washer
When the washer switch is depressed, voltage is supplied to the solid-state control board in the wiper motor module.
The control board supplies battery voltage to the washer motor through CKT 228 (RED).
The control board starts the wiper cycle through the low speed brushes of the wiper motor.
The washer continues to run as long as the washer switch is depressed.
The solid-state control board keeps the wipers on for approximately six seconds after the washer goes off.
If the washer is switched ON during the DELAY operation, the wipers run in low speed for six seconds.
When the wash cycle is completed, the wipers return to the pulse operation.