Wiper and Washer Systems: Description and Operation
WIPERS / WASHERSFRONT WIPER / WASHER SYSTEM
The windshield wipers can be operated with the windshield wiper switch when the ignition switch is in the RUN or ACCESSORY positions. The windshield wiper system is protected by a 30 amp fuse (9) located in the Power Distribution Center (PDC) part of the Integrated Power Module (IPM) in the engine compartment. The wiper/washer switch is integral to the multi-function switch. It is a resistive MUX switch that sends inputs to the BCM to operate the wiper/washer system.
The windshield washer circuit is protected by a 15 amp Cartridge Fuse located in the IPM. The wiper motor has permanent magnetic fields. The speeds are determined by current flow to the appropriate set of brushes inside the motor. The current flow is controlled by the multi-function switch. The high speed/low speed relays are located in the IPM. The speed sensitive intermittent wiper is controlled by the Body Control Module (BCM). The intermittent mode, with the vehicle traveling greater than 10.4 mph, has a range of 0.5 - 18 seconds. With the vehicle traveling less than 10.4 mph, the time delay doubles to a range of 1 - 36 seconds. The wiper arms will park at the base of the windshield just above the cowl cover after the wiper switch is turned OFF.
The windshield wiper motor and linkage is located in an integral wiper unit at the rear of the engine compartment. The wiper unit must be removed to gain access to the wiper motor.
The front wiper/washer system consists of the following features: lo-hi-speed, mist wipers, intermittent wipers and wipe after wash. The front wiper system is only active when the ignition switch is in the RUN/ACC position. The vehicle operator selects the front wiper function using the front wiper switch (a resistive multiplexed stalk switch) which is integral to the Multi-Function Switch. The front wiper switch is hardwired to the Body Control Module (BCM). Upon receiving a wiper switch signal, the BCM sends a PCI Bus message to the Front Control Module (FCM). The FCM controls the ON/OFF relay, the HIGH/LOW relay and the front and rear washer pump motors.
The Wiper system utilizes the BCM to control the on/off and hi/low relays for the low and hi speed wiper functions, intermittent wiper delay as the switch position changes, pulse wipe, wipe after wash mode and wiper motor functions. The BCM uses the vehicle speed input to double the usual delay time below 10 mph (6 km/h).
Speed Sensitive Intermittent Wipe Mode
There are 5 individual delay time settings with a minimum delay of 1.7 seconds to a maximum of 18.4 seconds. When the vehicle speed is under 10 mph (6 km/h), the delay time is doubled, providing a delay range of 3.4 - 36.8 seconds.
Pulse Wipe
When the wiper is in the OFF position and the driver presses the wash button for more than 0.062 seconds, but less than 0.5 seconds, 2 wipe cycles in low speed mode will be provided.
Park After Ignition Off
Because the wiper relays are powered from the battery, the BCM can run the wipers to park after the ignition is turned OFF,
Wipe After Wash
When the driver presses the wash button for over 0.5 seconds and releases it, the wiper will continue to run for 2 additional wipe cycles.
REAR WIPER / WASHER SYSTEM
The rear windshield wiper and washers can be operated when the ignition switch is in the RUN or ACCESSORY positions.
When continuous rear wiper operation is required, the BCM will provide ignition ON voltage to the rear wiper motor. When the wiper switch is turned OFF, the BCM provides circuit ground to operate the motor until the wipe cycle is complete and the wiper arm returns to the base of the rear window.
When intermittent rear wiper mode is selected, the wiper motor will cycle every 7 seconds. The intermittent delay time is also adjusted based upon vehicle speed. With the vehicle traveling greater than 50 mph, the cycle changes to every 5 seconds.
The rear wiper/washer system consists of the following features: mist wipers, intermittent wipers and wipe after wash. The rear wiper system is only active when the ignition switch is in the RUN/ACC position. The vehicle operator selects the rear wiper function using one of the three buttons on the dash mounted rear wiper switch. The rear wiper switch is hardwired to the Body Control Module (BCM). Upon receiving a wiper switch signal, the BCM provides 12 volts to the rear wiper motor. Rear washer occurs when the BCM receives a rear washer switch ON input. The BCM sends a PCI Bus message to the FCM requesting rear washer on.
The FCM activates the rear washer by providing a ground for the rear washer motor.
Speed Sensitive Intermittent Wipe Mode
The delay setting of the rear wiper system is based solely on the vehicle speed. The delay time is defined as the amount of time from the start of a wipe to the beginning of the next wipe. The rear wiper system delay time is based on the following: 7.75 - (mph x .05) = Seconds delay
Examples:
At zero (0) mph the delay is 7.75 seconds.
At 100 mph the delay is 2.75 seconds.
Wipe After Wash
When the driver presses the wash button for over 1.5 seconds and releases it, the wiper will continue to run for 2 additional wipe cycles.
Fig.5 HVAC Control Panel:
REAR WIPER / WASHER SWITCH
The rear window wiper/washer switches are located on the center bezel with the hazard and heated seat switches. They are not serviceable separately from the hazard and heated seat switches. If defective, the entire switch assembly must be replaced.
Refer to the vehicle Owner's Manual for operating instructions for the rear window wiper and washer.
REAR WINDOW DEFOGGER / HEATED MIRROR / FRONT WIPER DE-ICE
The defroster button located on the HVAC control controls the rear window defogger, heated side view mirrors and front wiper de-icer grid. In addition the front wiper de-ice function is turned on when front defog/defrost mode is selected.
When the defroster button is pushed, the HVAC control sends a bus message over the PCI bus to the Front Control Module (FCM) which controls the Rear Window Defogger relay. The defroster LED will illuminate when the defroster function is on. The defroster will function for 10 minutes or can be cycled off sooner by pressing the defroster button again. The front wiper de-icer grid receives its 12 volts from the accessory relay through fuse 11 and the HVAC control module supplies the grid ground.