Windshield Wiper/Washer System Description and Operation
The windshield wiper/washer switch supplies voltage on the signal circuit or the control circuit of the windshield washer pump to the BCM for windshield wiper/washer operation. When WASH, MIST, DELAY, LOW, or HIGH is detected, the BCM energizes the Wiper 1 relay by suppling voltage to the relay coil. This allows battery voltage from the WIPER fuse to flow through the relay switched input then through the contacts and out the relay switched output to the WIPER 2 relay switch contacts. Since the WIPER 2 relay switch contacts are normally closed to the low speed circuit of the windshield wiper motor, the motor will operate at low speed.
Wash Operation
In the WASH position windshield wiper/washer switch supplies voltage on the control circuit of the windshield washer pump to the BCM and the windshield washer pump. The BCM monitors this voltage input to detect when a WASH cycle is requested so it can enable the wipers. The BCM energizes the Wiper 1 relay which will operate the windshield wiper motor at low speed.
The windshield washer pump sprays solvent onto the windshield. The windshield wipers operate at low speed for 3-5 wipes and returns to the park position.
Mist Operation
In the MIST position, voltage is supplied through a internal 562 ohms resistor to the signal circuit of the windshield wiper/washer switch for the BCM. The BCM will momentarily energizes the Wiper 1 relay which will operate the windshield wiper motor at low speed.
The windshield wipers make one sweep at low speed and returns to the park position. If the windshield wiper/washer switch is held in MIST mode, the windshield wipers will continue to operate until the switch is released.
Intermittent Operation
In the desired INT position, the BCM will cycle the Wiper 1 relay ON and OFF to acquire the desired intermittent speed of the windshield wiper motor. The intermittent speed of the windshield wipers can also be effected by the vehicle speed. Refer to Vehicle Speed Sensitive Wipers for more information.
In the INT position 1, voltage is supplied through the following internal resistors to the signal circuit of the windshield wiper/washer switch for the BCM.
- 4640 ohms
- 1780 ohms
- 909 ohms
- 562 ohms
In the INT position 2, voltage is supplied through the following internal resistors to the signal circuit of the windshield wiper/washer switch for the BCM.
- 1780 ohms
- 909 ohms
- 562 ohms
In the INT position 3, voltage is supplied through the following internal resistors to the signal circuit of the windshield wiper/washer switch for the BCM.
- 909 ohms
- 562 ohms
Low Operation
In the Low position, voltage is supplied through a internal 562 ohms resistor to the signal circuit of the windshield wiper/washer switch for the BCM. The BCM will energizes the Wiper 1 relay which will operate the windshield wiper motor at low speed.
High Operation
In the High position, the windshield wiper/washer switch supplies voltage to both the Wiper 1 and Wiper 2 relay coils. This energizes both relays and allows battery voltage from the Wiper 1 relay switched output to the switched input of the Wiper 2 relay through its contacts and out the switched output of the relay to the high speed circuit of the windshield wiper motor. The windshield wiper motor will operate at high speed.
Park Position Operation
The BCM supplies voltage to signal circuit of the windshield wiper motor park switch. The BCM monitors this signal to determine if the windshield wiper motor is still operating or it has parked. The signal will be pulled to ground by the windshield wiper motor park switch while the windshield wiper motor is operating. When the windshield wiper motor has parked, the signal is at normal voltage because of the windshield wiper switch being open.