Wiper System

WINDSHIELD WIPER & WASHER
Front Wiper
System Description
The front wiper 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 is in the run/ACC position.

The BCM controls the front wiper system with one low-going output to a relay. With this output the BCM determines the motor wipe rate. This rate is a function of the intermittent wiper switch position and vehicle speed. The BCM times the delay after the wipers have parked. If the driver goes from a longer to a shorter delay interval a wipe is done immediately. The speed sensitive delay is set based on the current speed of the vehicle. If the vehicle crosses above the speed threshold while the intermittent wiper delay is occurring a smaller delay can be used. If the vehicle crosses below the speed threshold a longer delay should not be used until the current delay is completed.

In the LO-HI and mist state the BCM constantly outputs an active control signal for a delay of zero. The multifunction switch controls the wiper high/low relay wiper motor in the hi state. This is done with an additional output from the multifunction switch to a relay which selects the motor winding to be energized. The BCM does not distinguish between lo-hi-or mist positions. The mist position is a momentary input to the BCM which causes the wipers to operate at low speed as long as the mist input is present.

The BCM also monitors the front washer motor to perform wipe after wash. The BCM will perform a number of wipes after the wash input is released.

Since the front wiper system is an important safety feature the BCM will support wiper operation in the event of a failed park input.

If BCM does not detect a change of state on the park input for 8 seconds with the wiper relay energized a Diagnostic Trouble Code will set in the BCM.

Once a failed park switch is detected intermittent operation is disabled and the BCM will default to the low speed wiper state when the wiper switch is in the intermittent position. The wiper relay will be de-energized when the wiper mode switch is in the OFF position. For open and short states on the wiper mode switch the wipers should default to OFF.

System Features
Speed Sensitive Intermittent Wipe Mode
There are 5 individual delay times with a minimum delay of 1/2 second to a maximum of 18 seconds. When the vehicle speed is under 10 MPH the delay time is doubled providing a range of 1 second to 36 seconds.

Pulse Wipe
The wiper is in the OFF position and the driver presses the wash button for more than 62 milliseconds but less than 1/2 second 2 wipe cycle 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 1/2 second and then releases it the wiper will continue to run for 2 additional wipe cycles.

The wiper system utilizes the BCM to control the ON/OFF and high/low relays for low wiper functions intermittent wiper delay as the switch position changes pulse wipe wipe after wash mode and wiper motor park functions. The BCM uses the vehicle speed input to double the usual delay time below 10 MPH. There are three diagnostic trouble codes associated with the wiper system.

Front/Rear Wiper and Washer Switches (Right Multi-Function switch Stalk)
The front windshield and rear liftglass wiper/washer Switches are located on the wiper multi-function switch stalk which is secured to the right side of the multi-function switch mounting housing on the steering column.

A knob on the end of the wiper multifunction switch stalk is rotated to select the desired front wiper speed (HIGH or LOW) or one of the five intermittent front wiper positions. The wiper stalk is pulled toward the driver to activate the windshield washer system. Both the front wiper and front washer motors will operate continuously for as icing as the stalk is held in the momentary FRONT WASH position.

Another rotary switch on the wiper multifunction switch stalk is rotated to select the desired rear wiper speed (ON or DELAY). The wiper stalk is pushed toward the instrument panel to activate the rear liftglass washer system. Both the rear wiper and rear washer motors will operate continuously for as long as the stalk is held in the momentary REAR WASH position.

If any part of the right multi-function switch stalk is faulty or damaged the entire wiper multifunction switch assembly must be replaced.

Rear Wiper System
Five circuits feed the rear wiper module. It has two high current circuits battery (B+) and ground that run the motor. The remaining three circuits are low current control circuits.

TWO of these circuits come from the rear wiper switch on the right multi-function switch stalk. These circuits are referred to as the rear wiper motor control circuit and the rear wiper motor intermittent control circuit. When the rear wiper switch is in the Off position both of these circuits are open and the wiper module parks or remains parked. When the rear wiper switch is in the Intermittent position the intermittent control circuit is Switched to ignition voltage the motor control circuit is open and the wiper is in the intermittent modes. When the rear wiper switch is in the On position the intermittent control circuit is open and the motor control circuit is Switched to ignition voltage and the wiper is in continuous wipe mode.

The third control circuit is the AJAR circuit. This circuit is fed by the one flip-up glass and the two liftgate ajar Switches. When the liftgate is closed the ajar Switches are open and the rear wiper module functions normally When either the liftgate and/or flip-up glass are open those particular ajar Switches close and the circuit provides ground to the module. This ground signal indicates to the rear wiper module that it should park if operating or not allow operation if parked.