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FRONT WIPER AND WASHERAn electrically operated intermittent front wiper and washer system is standard factory-installed safety equipment on this model. The front wiper and washer system includes the following major components, which are described in further detail elsewhere in this service information:
- Central Timer Module - The Central Timer Module (CTM) is located on the left cowl side inner panel under the driver side outboard end of the instrument panel. The CTM contains a microprocessor and software that allow it to provide the many electronic functions and features not available with most conventional hard wired wiper and washer systems. The CTM provides the proper front wiper and washer system features based upon the monitored inputs. The CTM circuitry monitors hard wired switch inputs, as well as message inputs received from other vehicle electronic modules on the Programmable Communications Interface (PCI) data bus network. (Refer to ELECTRONIC CONTROL MODULES/BODY CONTROL/CENTRAL TIMER MODULE - DESCRIPTION).
- Front Washer Nozzles - The dual fluidic washer nozzles are secured with integral snap features to dedicated openings in the cowl plenum coven grille panel located near the base of the windshield. The washer plumbing fittings for the washer nozzles are concealed beneath the cowl plenum cover/grille panel.
- Front Washer Pump/Motor - The front washer pump/motor unit is located in a dedicated hole near the bottom of the windshield washer reservoir on the right end of the upper radiator shroud. The front washer pump is located below the rear washer pump.
- Front Wiper Arms - The two front wiper arms are secured to the two front wiper pivots, which extend through the cowl plenum cover/grille panel located near the base of the windshield.
- Front Wiper Blades - The two front wiper blades are secured to the two front wiper arms, and are parked on the glass near the bottom of the windshield when the wiper system is not in operation.
- Front Wiper Module - The front wiper pivots are the only visible components of the front wiper module. The remainder of the module is concealed within the cowl plenum beneath the cowl plenum cover/grille panel. The front wiper module includes the module bracket, the single front wiper motor, the front wiper linkage, and the two front wiper pivots.
- Front Wiper Relay - The front wiper relay is located in the Power Distribution Center (PDC) in the engine compartment near the battery.
- Multi-Function Switch - The multi-function switch is secured to the left side of the steering column, just below the steering wheel. Only the control stalk for the multi-function switch is visible, the remainder of the switch is concealed beneath the steering column shrouds. The multi-function switch contains all of the switches for both the front wiper and washer systems. (Refer to LAMPS/LIGHTING - EXTERIOR/MULTI-FUNCTION SWITCH - DESCRIPTION)
- Washer Fluid Level Switch - The washer fluid level switch is located in a dedicated hole near the front of the windshield washer reservoir on the right outboard end of the upper radiator shroud.
- Washer Reservoir - The washer reservoir is integral to and located on the right end of the upper radiator shroud. The washer reservoir filler is accessed from the right front corner of the engine compartment.
Features of the front wiper and washer system include the following:
- Continuous Wipe Modes - The two-speed wiper motor and the internal circuitry of the multi- function switch work in concert to provide two continuous wipe cycles, low speed or high speed.
- Intermittent Wipe Mode - The internal circuitry of the multi-function switch, the CTM, and the front wiper relay work in concert to provide an intermittent wipe mode with multiple delay interval selections. The CTM also automatically adjusts each manually selected delay interval to compensate for vehicle speed.
- Washer Mode - When the front washer system is activated with the multi-function switch while the front wiper system is operating, washer fluid will be dispensed onto the windshield glass through the front washer nozzles for as long as the front washer pump/motor is energized.
- Wipe-After-Wash Mode - The internal circuitry of the CTM provides a wipe-after-wash feature which, if the front wipers are turned OFF, will operate the front washer pump/motor and the front wipers for as long as the front washer system is activated, then provide several additional wipe cycles after the front washer system is deactivated before parking the front wiper blades near the base of the windshield.
Hard wired circuitry connects the front wiper and washer system components to the electrical system of the vehicle. These hard wired circuits are integral to several wire harnesses, which are routed throughout the vehicle and retained by many different methods. These circuits may be connected to each other, to the vehicle electrical system and to the front wiper and washer system components through the use of a combination of soldered splices, splice block connectors, and many different types of wire harness terminal connectors and insulators.
The front wiper and washer system is intended to provide the vehicle operator with a convenient, safe, and reliable means of maintaining visibility through the windshield glass. The various components of this system are designed to convert electrical energy produced by the vehicle electrical system into the mechanical action of the wiper blades to wipe the outside surface of the glass, as well as into the hydraulic action of the washer system to apply washer fluid stored in an on-board reservoir to the area of the glass to be wiped. When combined, these components provide the means to effectively maintain clear visibility for the vehicle operator by removing excess accumulations of rain, snow, bugs, mud, or other minor debris that might be encountered while driving the vehicle under numerous types of inclement operating conditions from the outside windshield glass surface. The vehicle operator initiates all front wiper and washer system functions with the multi- function switch control stalk that extends from the left side of the steering column, just below the steering wheel. Rotating the knob on the end of the multi- function switch control stalk selects the desired front wiper system operating mode. The front wiper system allows the vehicle operator to select from two continuous wiper speeds, Hi or Lo, or one of several intermittent wipe Delay mode intervals. Pushing the knob on the end of the control stalk towards the steering column activates the front washer pump/motor, which dispenses washer fluid onto the windshield glass through the front washer nozzles.
When the ignition switch is in the Accessory or ON positions, battery current from a fuse in the Junction Block (JB) is provided through a fused ignition switch output (run-acc) circuit to the front wiper motor park switch, the front wiper relay, and the multi-function switch. The internal circuitry of the multi-function switch provides a direct hard wired battery current output to the low speed or high speed brushes of the front wiper motor when the Lo or Hi switch setting is selected, which causes the front wipers to cycle at the selected speed. The intermittent wipe, and wipe-after-wash features of the front wiper and washer system are provided by the electronic intermittent wipe logic circuit within the Central Timer Module (CTM). In order to provide the intermittent wipe feature, the CTM monitors the front wiper switch state and the front wiper motor park switch state. In order to provide the wipe-after-wash feature, the CTM monitors both the front washer switch state and the front wiper motor park switch state. When a Delay position is selected with the multi-function switch control knob, the CTM logic circuit responds by calculating the correct delay interval. The CTM then energizes the front wiper relay by pulling the relay control coil to ground. The energized front wiper relay directs battery current through the normally open contact of the relay back through the internal Delay position circuitry of the multi-function switch to the low speed brush of the front wiper motor. The CTM monitors the front wiper motor operation through the wiper park switch sense circuit, which allows the CTM to determine the proper timing to begin the next wiper blade sweep. The normal delay intervals are driver adjustable from about one-half second to about eighteen seconds.
The CTM also provides a speed sensitive intermittent wipe feature. By monitoring vehicle speed messages received from the Powertrain Control Module (PCM) over the Programmable Communications Interface (PCI) data bus network, the CTM is able to adjust the delay intervals to compensate for vehicle speed. Above about 16 km/h (10 mph) the delay is driver adjustable from about 1/2 second to about 18 seconds. Below about 16 km/h (10 mph) the delay times are doubled by the CTM, from about one second to about 36 seconds.
When the OFF position of the multi-function switch wiper control knob is selected, one of two events is possible. The event that will occur depends upon the position of the wiper blades on the windshield at the moment that the OFF position is selected. If the wiper blades are in the down position on the windshield when the OFF position is selected, the park switch that is integral to the front wiper motor is closed to ground and the wiper motor ceases to operate. If the wiper blades are not in the down position on the windshield at the moment the OFF position is selected, the park switch is closed to battery current through a fused ignition switch output (RUN/ACC) circuit. The park switch sense circuit directs this battery current to the low speed brush of the front wiper motor through the normally closed contact of the front wiper relay and the internal OFF position circuitry of the multi-function switch. This causes the front wiper motor to continue running until the wiper blades are in the down position on the windshield and the park switch is again closed to ground.
When the Wash position of the multi-function switch is selected, the Wash position circuitry within the switch directs a battery current signal input to the CTM. The CTM monitors the front washer switch state through this input to control a battery current output to the front washer pump/motor unit. When the front washer switch is closed with the front wiper system turned OFF, the CTM operates the front wiper motor through the front wiper relay in the same manner as it does to provide the Delay mode operation. After the state of the front washer switch changes to open, the CTM monitors the front wiper motor through the wiper park switch sense circuit, which allows the CTM to monitor the number of wiper blade sweeps. After the appropriate number of wiper sweeps, the CTM de-energizes the front wiper relay and the wipers return to their park position.
Proper testing of the CTM, the PCM, or the PCI data bus vehicle speed messages requires a DRB III scan tool. Refer to the appropriate diagnostic information. Refer to the owner's manual in the vehicle glove box for more information on the features and operation of the front wiper and washer system.
FRONT CHECK VALVE
A front washer system check valve is standard equipment on this model. The check valve is integral to the front washer nozzle plumbing eye fitting located in the cowl plenum beneath the cowl plenum cover/grille panel near the base of the windshield. The front check valve consists of a molded plastic body with a round center. Three barbed hose nipples are formed in a eye configuration on the outside circumference of the center of the valve body. Within the check valve body, a small check valve operated by a small coiled spring restricts flow through the unit until the valve is unseated by a predetermined inlet fluid pressure. The front check valve cannot be adjusted or repaired and, if faulty or damaged, it must be replaced.
The front check valve provides more than one function in this application. It serves as a eye connector fitting between the cowl grille panel and washer nozzle sections of the front washer supply hose. It also prevents washer fluid from draining out of the washer supply hoses back to the washer reservoir. This drain-back would result in a lengthy delay from when the washer switch is actuated until washer fluid was dispensed through the front washer nozzles, because the front washer pump would have to refill the front washer plumbing from the reservoir to the nozzles. Finally, the front check valve prevents washer fluid from siphoning through the front washer nozzles after the washer system is turned OFF. When the front washer pump pressurizes and pumps washer fluid from the reservoir through the front washer plumbing, the fluid pressure overrides the spring pressure applied to the check valve and unseats the valve, allowing washer fluid to flow toward the front washer nozzles. When the front washer pump stops operating, spring pressure seats the check valve and fluid flow in either direction within the front washer plumbing is prevented.