Wiper and Washer Systems: Description and Operation
GENERAL INFORMATIONMulti-Function Switch
WARNING: VEHICLES ARE EQUIPPED WITH AN AIRBAG, REFER TO AIR BAGS AND SEAT BELTS/AIR BAGS FOR STEERING WHEEL OR COLUMN SERVICE PROCEDURES.
Multi-Function Switch:
The multi-function switch contains:
- Turn signals
- Hazard warning
- Headlamps
- Headlamp beam select
- Parking lamps
- Panel dimmer
- Fog Lamp
- Headlamp optical horn
- Windshield wiper
- Pulse wipe
- Mist wipe
- Windshield washer switches.
The multi-function switch is mounted center of the steering column. There are two levers, one on each side of the steering column. The left side controls the signaling and lighting. The right side controls the windshield wiper and washer system. To use the washers pull lever toward the driver. The mist is a single wipe operation by pushing lever down and releasing the lever. Intermittent wiper operation is controlled by the Body Control Module (BCM). The lever has a selection of delay intervals and by turning lever the wiper will cycle every half second to 36 seconds depending ON the vehicle's speed. The wiper has two cycle two speeds.
The windshield wipers will only operate when the ignition switch is in the ACCESSORY or IGNITION position. Fuse 15, located in the Junction Block, fuses 8 and 14 in the Power Distribution Center block, protects the wiper/washer system circuitry. The wiper motor also has an internal non-serviceable circuit breaker to provide protection against motor stall conditions.
The wiper and washer motors have magnetic fields created by internal permanent magnet. Electric power applied to the motor armature, located in the magnetic field, causes the motor to turn.
The wiper system internal operation uses the low speed motor circuit in combination with intermittent wipe relay. The washer pump motor has one internal circuit and therefore operates at one speed.
The wiper and washer system switch located on the steering column selects the mode of operation of the motors. The switch provides input to the BCM, which in turn operates the two relays. The intermittent wipe relay turns the wiper ON and OFF. The other changes the HIGH/LOW speeds. The switch also provides power to the washer pump motor.
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 when the vehicle speed is over 10 m.p.h. The wiper delay times will automatically double to a range of 1 to 36 seconds when the vehicle speed is less than 10 m.p.h. The delay is controlled by a van able resistor in the wiper switch and BCM.
The wiper motor and washer motor are designed to reduce radio frequency interference and provide electro-magnetic compatibility (RFI/EMC) in the vehicle environment. This is done with suppression circuits designed into the motors.
The wiper system completes the wipe cycle when the switch is turned OFF. The blades park iii the lowest portion of the wipe pattern.
When using a scan tool (DRB), refer to the Body Diagnostic for the procedures.
Windshield Washers
All models are equipped with electric operated windshield washer pumps. The wash function can be accessed in the OFF or ON position of the multi-function wiper control switch.
SYSTEM OPERATION
Windshield Washers
Pulling the lever towards the driver when the wiper switch is in the OFF position will operate the wipers and washer motor pump continuously until the lever is released. Releasing the lever 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 just before 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 not adjustable. The pump and reservoir are serviced as separate assemblies.
Wiper Blade - Typical:
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 driver and the passenger blade elements are 550 mm in length. Only the driver's side wiper blade has a air foil on it.
CIRCUIT OPERATION
Windshield Wipers
The windshield wiper system is powered by a 10 amp fuse located in cavity 15 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 8.
The F13 circuit supplies the power from the fuse in the junction block to the wiper switch, coil side if the intermittent wiper relay, and the coil side of the HI/LOW Wiper relay. This circuit is spliced and also supplies power to the Rear Window Defogger relay, and the Turn Signal Combo F1asher. 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.
Intermittent Wiper
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 40 amp fuse located in cavity 14 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.
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 40 amp fuse located in cavity 14 of the 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.
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 VSS, for wiper position and system operation.
Mist Function
When the MIST switch is activated, and the wiper switch is in the OFF position, a multi-plexed signal is sent to the Body Control Module (BCM) on circuit V52. The BCM then turns the wipers on LOW speed for as long as the switch is held.
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 40 amp fuse located in cavity 14 of the 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.
If after the MIST switch is released and the wiper control switch is no longer in the OFF position, the wipers will enter the mode indicated by the wiper control 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.
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 40 amp fuse located in cavity 14 of the 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.
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.
HI 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 PDC and is protected by a 40 amp fuse located in cavity 14, 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.
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 right frame rail.