Wiper and Washer Systems: Description and Operation
WINDSHIELD WIPERSFeature Description
The Ram Van equipped with a CTM will utilize speed sensitive intermittent wipe and wipe after wash function. The driver selects the Wiper function via a Steering Column mounted Stalk Switch. The Wiper system is operational whenever the ignition switch is in the Run or Accessory positions only (not during engine crank).
The low and high speeds are controlled through the wiper stalk switch. The intermittent portion of the wiper control is handled by the CTM through the intermittent wiper relay. When the module detects a decrease in delay time as selected by the driver, and immediate wipe of the windshield takes place and the new delay interval is implemented.
An Intermittent Wipe cycle consists of operating the Wipers in the Low Speed mode for one cycle, then executing a delay time. The delay time available to the driver is adjustable from 1/2 second to 18 seconds.
Speed Sensitive Intermittent Wipe Operation
Speed Intermittent Wipe is operational whenever the Ignition Switch is in either the RUN or ACCESSORY positions, and the voltage on the intermittent wiper switch MUX input is greater than 4.5 VDC.
The resistance selected by the stalk switch is used to set the delay time between wipe cycles.
The Intermittent Wipe DelayTime is also adjusted based upon Vehicle Speed. When the Vehicle Speed is < 10 MPH then the driver selected Delay Time is doubled providing a range from 1 second to 36 seconds. When the vehicle speed is > 10 MPH then the driver selected Delay Time is not adjusted. An immediate Low Speed mode Wipe cycle will occur and a new Delay Time interval will start if the driver changes the current selected Delay Time to a shorter interval. The speed signal is provided to the CTM from the PCM over the CCD bus.
Wipe After Wash Operation
Wipe after Wash operation activates the Wiper system when the Wash button is pressed. Wiper after Wash operation is available while the wiper switch is OFF or in Intermittent mode, and operates the Wipers in a Low Speed continuous cycling mode while the Wash button is held on. After the Wash button is released, 2 additional complete cycles are performed at Low Speed. The Wiper system returns to the previous mode of operation following the completion of the additional Wipe cycles.
Self Calibration
A self calibration feature is used to eliminate performance variations due to tolerances in the resistances of the intermittent wiper switch. Following a power on reset, a default value is copied to a battery backed RAM memory location. If a valid resistance value greater than the current battery backed compensation value is measured during intermittent wiper operation, and it is present for 8 consecutive samples, the compensation value is replaced by the average of the compensation value and the new resistance value. This compensation value is used to calculate the intermittent wiper delay, using the following formula:
Delay in seconds = 0.5 + 17.5* (resistance value/compensation value)
Three EEPROM locations have been provided to allow for optional calibration of the intermittent wipers. One location specifies a constant which will override the battery backed compensation value. The other locations specify constants which will override the default offset and slope used in converting resistance to time delay.
Failed Wiper Park Switch
A failed Wiper Park Switch is determined by the CTM "C1" PIN #11 input remaining high for eight seconds when the wiper system is in intermittent mode. Once detected, a code flag will be set in the EEPROM fault record byte.
Once the Failed Wiper Park Switch fault is set, the intermittent wiper function will not operate until a low is seen on the CTM "C1" PIN #11 input with the ignition ON. The code flag may only be cleared manually using a DRB.
WIPERS / WASHERS
An electrically operated intermittent wiper and washer system is standard factory-installed safety equipment on this model.
The wiper and washer system includes the following major components, which are described in further detail elsewhere in this service information:
* Central Timer Module - A Central Timer Module (CTM) is used on this vehicle when it is equipped with the optional Vehicle Theft Security System (VTSS). The CTM is concealed under the instrument panel, where it is secured with three screws to the inboard side of the left center instrument panel support above the engine housing. 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 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 Chrysler Collision Detection (CCD) data bus network.
* Intermittent Wipe Module - An intermittent wipe module is used on vehicles that are not equipped with the optional Vehicle Theft Security System (VTSS). The intermittent wipe module is snap-fit onto a single blade-type mounting bracket located on the instrument panel cross body structural support above the glove box opening. Electronic circuitry within the intermittent wipe module is used to provide the intermittent wipe delay and the wipe-after-wash features of the intermittent wipe system based upon numerous hard wired inputs.
* 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 wiper and washer systems.
* 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 Nozzles - The dual fluidic washer nozzles are secured with integral snap features to dedicated openings in the cowl plenum cover/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.
* Washer Pump/Motor - The 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.
* 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.
* Wiper Arms - The two wiper arms are secured to the two wiper pivots, which extend through the cowl plenum cover/grille panel located near the base of the windshield.
* Wiper Blades - The two wiper blades are secured to the two wiper arms, and are parked on the glass near the bottom of the windshield when the wiper system is not in operation.
* Wiper Linkage - The wiper pivots are the only visible components of the wiper linkage. The remainder of the linkage is concealed within the cowl plenum beneath the cowl plenum cover/grille panel. The wiper linkage includes the wiper drive and connector links, and the two wiper pivots.
* Wiper Motor - The wiper motor is secured to the underside of the cowl plenum panel within the engine compartment. The wiper motor output shaft and crank arm extend through a clearance hole into the cowl plenum, where they are connected to and drive the wiper linkage.
* Wiper Relay - The wiper relay is used only on models equipped with the optional Vehicle Theft Security System (VTSS). The relay is located in a take out and connector that are taped to the instrument panel wire harness located on the instrument panel cross body structural support above the glove box opening.
Features of the 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 intermittent wipe module (without VTSS), or the CTM and the wiper relay (with VTSS) work in concert to provide an intermittent wipe mode with multiple delay interval selections. For models equipped with the optional VTSS, the CTM also automatically adjusts each manually selected delay interval to compensate for vehicle speed.
* Washer Mode - When the washer system is activated with the multi-function switch while the wiper system is operating, washer fluid will be dispensed onto the windshield glass through the washer nozzles for as long as the washer pump/motor is energized.
* Wipe-After-Wash Mode - The internal circuitry of the intermittent wipe module (without VTSS), or the CTM and wiper relay (with VTSS) provides a wipe-after-wash feature. If the wipers are turned Of{ this features will operate the washer pump/motor and the wipers for as long as the washer system is activated, then provide several additional wipe cycles after the washer system is deactivated before parking the wiper blades near the base of the windshield.
Hard wired circuitry connects the 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 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. Refer to the appropriate wiring information. The wiring information includes wiring diagrams, proper wire and connector repair procedures,further details on wire harness routing and retention, as well as pin-out and location views for the various wire harness connectors, splices and grounds.
The 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.
Two versions of the intermittent wipe system are used on this model; one version is used for vehicles not equipped with the optional Vehicle Theft Security System (VTSS) and has an intermittent wipe module that controls the intermittent wipe delay and wipe-after-wash features, while the other version is used only on vehicles equipped with the optional VTSS and has a Central Timer Module (CTM) that controls the intermittent wipe delay and wipe-after-wash features through a wiper relay With either system, the vehicle operator initiates all 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 wiper system operating mode. Each 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 washer pump/motor, which dispenses washer fluid onto the windshield glass through the washer nozzles.
When the ignition switch is in the Accessory or ON positions, battery current from a fuse in the fuse block is provided through a fused ignition switch output (run-acc) circuit to the wiper motor park switch, the intermittent wipe module (without VTSS) or the wiper relay (with VTSS), 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 wiper motor when the Lo or Hi switch setting is selected, which causes the wipers to cycle at the selected speed. In order to provide the intermittent wipe feature, the intermittent wipe module or the CTM monitors the wiper switch state and the wiper motor park switch state. In order to provide the wipe-after-wash feature, the intermittent wipe module or the CTM monitors both the washer switch state and the wiper motor park switch state. When a Delay position is selected with the multi-function switch control knob, the intermittent wipe module timer circuit or the CTM logic circuit responds by calculating the correct delay interval. The intermittent wipe module, or the CTM through the wiper relay, then directs battery current through the internal Delay position circuitry of the multi-function switch to the low speed brush of the wiper motor. The intermittent wipe module or the CTM monitors the wiper motor operation through the wiper park switch sense circuit, which allows them 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 Chrysler Collision Detection (CCD) data bus network, the CTM is able to adjust the delay intervals to compensate for vehicle speed. Above about sixteen kilometers-per-hour (ten miles-per-hour) the delay is driver adjustable from about one-half second to about eighteen seconds. Below about sixteen kilometers-per-hour (ten miles-per-hour) the delay times are doubled by the CTM, from about one second to about thirty-six seconds. The speed sensitive intermittent wipe feature is not available on models equipped with the intermittent wipe module.
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 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 wiper motor through the intermittent wipe module, or through the normally closed contact of the wiper relay, then through the internal OFF position circuitry of the multi-function switch. This causes the 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 washer pump motor, and to the intermittent wipe module or the CTM. When the washer switch is closed with the wiper system turned OFF, the intermittent wipe module, or the CTM through the wiper relay, operates the wiper motor in the same manner as it does to provide the Delay mode operation. After the state of the washer switch changes to open, the intermittent wipe module or the CTM monitors the wiper motor through the wiper park switch sense circuit, which allows them to monitor the number of wiper blade sweeps. After the appropriate number of wiper sweeps, the intermittent wipe module or the CTM de-energizes the wiper motor and the wipers return to their park position.
The hard wired inputs to and outputs from the wiper and washer system components can be diagnosed and tested using conventional diagnostic tools and methods. Proper testing of the CTM, the PCM, or the CCD 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 wiper and washer system.