Wiper and Washer Systems: Description and Operation
Wiper/Washer System Description and Operation
Wiper/Washer System Components
The windshield Wiper/Washer system consists of the following components:
* Body Control Module (BCM).
* Engine Control Module (ECM).
* Washer pump.
* Washer pump relay.
* Washer solvent container.
* Wiper arm and blade assemblies.
* Wiper motor.
* Wiper/washer switch.
* F15 30 A fuse.
* F21 15 A fuse.
* Wiper relay.
* Wiper high relay.
Windshield Wiper/Washer System Power and Ground
With the ignition in the ON position, accessory voltage is supplied through the F15 30A fuse to the wiper relay and the wiper high relay. Accessory voltage is supplied through the F21 15A fuse to the washer pump relay when the ignition is in the ON position. All of the above mentioned fuses and relays are located in the underhood fuse block.
G102 provides ground for the wiper motor and the wiper relay. G104 provides ground for the washer pump.
Modes Of Operation
* Manual low.
* Mist.
* Intermittent.
* Manual high.
* Wash.
Low Speed Operation
When the wiper switch is in the low speed position, ground is applied through a resistor internal to the switch and the wiper switch low signal circuit to the BCM. In response to this signal, the BCM energizes the wiper relay. Since the wiper high relay is de-energized and its switch contacts are normally closed to the low speed control circuit of the windshield wiper motor, the motor will operate at low speed.
Mist Operation
Windshield wiper/washer system mist operation is identical to wiper low speed operation, except that the mist switch is a press and release type switch. When the wiper switch is moved to the mist position and released, low speed wiper motor operation is started and will continue until 1 wipe cycle is complete. If the wiper switch is moved to the mist position and held, the wiper motor will operate in the low mode until the switch is released.
Intermittent Operation
Windshield wiper intermittent operation is a low speed wiper motor function with a variable delay interval between the wiper motor cycles. The delay interval is determined by a series of 6 resistors within the wiper/washer switch. The BCM monitors the wiper switch low signal circuit to determine the delay interval between the low speed wiper motor wipe cycles. The intermittent speed of the windshield wipers can also be effected by the vehicle speed. Refer to Vehicle Speed Sensitive Wipers for more information.
High Speed Operation
When the wiper switch is in the high speed position, ground is applied through the windshield wiper switch high signal circuit to the BCM indicating the wiper high speed request. In response to this signal, the BCM then energizes the wiper relay, by applying battery voltage through the wiper relay control circuit to the coil side of the relay. This allows battery positive voltage from the F21 15A fuse to flow through the switch input side of the wiper relay and out to the switch input side of the wiper high relay. At the same time, the BCM also energizes the wiper high relay by applying ground through the control circuit to the coil side of the wiper high relay. As the wiper high relay is energized and its switch contacts closed to the high speed control circuit of the wiper motor, the motor will operate at high speed.
Wash Operation
In the wash position windshield wiper/washer switch grounds the control circuit of the windshield washer pump to the BCM. The BCM monitors this voltage input to detect when a wash cycle is requested so it can enable the wipers. The BCM energises the wiper 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.