Wiper and Washer Systems: Description and Operation
INTRODUCTIONWARNING: VEHICLES ARE EQUIPPED WITH AN AIRBAG, REFER TO RESTRAINT SYSTEMS FOR STEERING WHEEL OR COLUMN SERVICE PROCEDURES.
The windshield wipers will only operated when the ignition switch is in the ACCESSORY or IGNITION run position. Fuses, located in the Junction Block and Power Distribution Center protects the circuitry of the wiper system and the vehicle.
The wiper motor has permanent magnet fields. The speeds are determined by current flow to the appropriate set of brushes.
The intermittent wiper system, in addition to low and high speed, has a delay mode. The delay mode has a range of 1/2 to 18 seconds. The wiper delay times will double to a range of 1 to 36 seconds when the vehicle speed is less than 10 mph. The delay is done by a variable resistor in the wiper switch and two relays. One relay turns the wipers ON/OFF and the other changes the speeds.
The wiper system completes the wipe cycle when the switch is turned OFF. The blades park in the lowest portion of the wipe pattern.
When using the scan tool (DRB), refer to the Body Chassis Diagnostic procedures.
The windshield wiper system is powered by a 10-amp fuse located in cavity 10 of the junction block. This fuse is HOT in the ACCESSORY and RUN positions only. Power for the fuse is supplied on the A31 circuit.
The A31 circuit originates at the ignition switch. Power for the A31 circuit is supplied by circuit A1 from the Power Distribution Center (PDC) and protected by a 20-amp fuse located in cavity A.
The F13 circuit supplies the power from the fuse in the junction block to the wiper switch, coil side of the intermittent wiper relay, and the coil side of the HI/LOW Wiper relay. Both of the relays used in the wiper system are located in the PDC.
The Body Control Module (BCM) controls all functions of the wiper system. This is accomplished through a multi-plexed input from the wiper switch to the BCM on circuit V52.
SYSTEM OPERATION
Windshield Washers
All models are equipped with electric operated windshield washer pumps.
The wash function can be accessed in the OFF position of the wiper control switch. Wash switch must be pressed for at least 0.5 second to get the wipe after wash. Holding the wash button depressed when the switch is in the OFF position will operate the wipers and washer motor pump continuously until the washer button is released. Releasing the button will stop the washer pump but the wipers will complete the current wipe cycle. Followed by an average of two more wipe cycles (± 1) before the wipers park and the module turns off.
The electric pump assembly is mounted with a grommet directly to the reservoir. Fluid is gravity fed from the reservoir to the motor. The fluid is forced by the pump through rubber hoses to the hood mounted nozzles which direct the fluid streams to the windshield. The hose assembly has two one way flow check valves located in each hood nozzle. The purpose of the check valves is to improve fluid flow response time and to prevent excessive washer fluid staining the surface of the hood. The hood mounted nozzles evenly distribute washer fluid across the surface of the windshield. The nozzles are adjustable, refer to the Washer Nozzle Adjusting Procedures. The pump and reservoir are serviced as separate assemblies.
Wiper Blades
When the wiper blade rubber element is exposed to the weather for a long period of time, it tends to lose wiping ability Periodic cleaning of the wiper blade element is suggested to remove the accumulation of salt and road film. The wiper blades, arms, and windshield should be cleaned with a sponge or cloth and a mild detergent or non abrasive cleaner. If the blades continue to streak or smear, they should be replaced. The right and left wipers are the same blade lengths. The blade lengths are 600 mm.
CIRCUIT OPERATION
Intermittent Wiper Operation
When the operator selects intermittent wiper operation a multi-plexed signal is sent to the Body Control Module (BCM) on the V52 circuit. The BCM then grounds circuit V14, which is the coil side of the intermittent wiper relay. This causes the relay to switch from its normally grounded position and connect circuit A5 to circuit V5. The A5 circuit is protected by a 30 amp fuse located in cavity E of the Power Distribution Center (PDC).
The V5 circuit is connected to the HI/LOW Wiper relay LOW speed side. Voltage is passed through the relay to circuit V3, then to the LOW speed side of the wiper motor. Ground for the wiper motor is provided on circuit Z1, and terminates at the left front frame rail.
When the wiper motor completes one cycle, the BCM turns OFF the motor by deactivating the wiper relays. The amount of delay between wipes is dependent on the voltage level being sent to the BCM from the wiper switch.
As the windshield wiper motor turns, the park switch internal to the motor moves from its grounded position to the open RUN position. The BCM uses input from the park switch, on circuit V55, for wiper position and system operation.
The delay times are also compensated for vehicle speed. If the vehicle is moving less than 10 mph, the delay time is doubled. Once the vehicle speed exceeds 10 mph, the normal delay times are used.
Wiper After Wash
When the wash button is pressed momentarily a signal is sent to the Body Control Module (BCM) on circuit V10. The BCM then turns the wipers ON low speed for three consecutive wipes after the button is released.
The BCM turns the wipers ON by providing a ground path for circuit V14. This causes the intermittent wipe relay to switch from its normally grounded position and connect circuit A5 to circuit V5. The A5 circuit is protected by a 30 amp fuse located in cavity E of the Power Distribution Center (PDC).
The V5 circuit is connected to the HI/LOW Wiper relay LOW speed side. Voltage is passed through the relay to circuit V3, then to the LOW speed side of the wiper motor. Ground for the wiper motor is provided on circuit Z1, and terminates at the left front frame rail.
Low Speed Operation
When the LOW speed switch is activated a multiplexed signal is sent to the Body Control Module (BCM) on circuit V52. The BCM then turns the wipers ON low speed by providing a ground path for circuit V14. This causes the intermittent wipe relay to switch from its normally grounded position and connect circuit A5 to circuit V5. The A5 circuit is protected by a 30 amp fuse located in cavity E of the Power Distribution Center (PDC).
The V5 circuit is connected to the HI/LOW Wiper relay low speed side. Voltage is passed through the relay to circuit V3, then to the LOW speed side of the wiper motor. Ground for the wiper motor is provided on circuit Z1, and terminates at the left front frame rail.
As the windshield wiper motor turns, the park switch internal to the motor moves from its grounded position to the open RUN position. The BCM uses input from the park switch, on circuit V55, for wiper position and system operation.
High Speed Operation
When HIGH speed operation is selected, a multiplexed signal is sent to the Body Control Module (BCM) on circuit V52. The BCM then turns the wipers ON by grounding the V14 and V16 circuits.
By grounding the V14 circuit the intermittent wiper relay is switched from its normally grounded position to connect circuits A5 and V5. The A5 circuit, which originates in the Power Distribution Center (PDC) and is protected by a 30 amp fuse located in cavity E, then supplies power to the HI/LOW wiper relay through circuit V5.
When the V16 circuit is grounded the HI/LOW relay switches, from its normal position of LOW speed, to the HIGH speed contact. Power for the coil side of the relay is supplied by the F13 circuit. This circuit also is the feed for the wiper switch and the intermittent wiper relay.
Power for the windshield wiper motor is supplied from the HI/LOW wiper relay to the motor on circuit V4. Ground for the wiper motor is provided on circuit Z1, and terminates at the left front frame rail.
As the windshield wiper motor turns, the park switch internal to the motor moves from its grounded position to the open RUN position. The BCM uses input from the park switch, on circuit V55, for wiper position and system operation.
Washer Operation
When the operator presses the WASH switch, power is supplied on the F13 circuit, through the CLOSED switch contacts, to circuit V10. The V10 circuit is spliced and connects to the Body Control Module (BCM) and the windshield washer pump motor. The pump motor, which is located in the washer fluid reservoir, is grounded at the left front frame rail.