Description And Operation - Front

DESCRIPTION 

Courtesy of CHRYSLER GROUP, LLC

The front wiper system consists of the following components:

1.	Refer to FRONT WIPER ARMS AND BLADES .
2.	Refer to LIGHT RAIN SENSOR MODULE (LRSM) .
3.	Refer to STEERING COLUMN CONTROL MODULE (SCCM)  - Activation controls.
4.	Refer to BODY CONTROL MODULE (BCM) .
5.	Refer to WASHER FLUID HOSES AND TUBES .
6.	Refer to WASHER FLUID LEVEL SENSOR .
7.	Refer to TWO-WAY WASHER PUMP  - for the front and rear washer circuit.
8.	Refer to WASHER FLUID RESERVOIR .
9.	Refer to WIPER MOTOR AND LINKAGE .
10.	Refer to WASHER FLUID NOZZLES  - with integral check valves.

Front and rear wipers and washers are standard equipment on this vehicle. Both wiper and washer systems are controlled by the right stalk of the SCCM which sends MUX signal inputs to the BCM to determine what function or functions of the system are activated or deactivated. The BCM controls the wiper and washer system by providing Low Side Driver (LSD) inputs to the relays in the BCM which activate the electric motors that drive the wiper or washer when selected by the driver. The Fused B+ output to the wiper and washer pump motors are protected by a 20 amp fuse in the BCM. The relays are not serviceable separately as they are soldered to the printed circuit board of the BCM.

The vehicle may be equipped with a rain detection sensor on the windshield. When rain/water is detected on the windshield, the system will automatically operate the wipers. The system uses an infrared sensor fitted behind the windshield in front of the interior rear view mirror. The sensor continuously sends infrared rays against the windshield to detect the presence of water on the glass; if detected, the sensor will send a signal on the Local Interface Network (LIN) data bus to the BCM, which will activate the wiper at the appropriate speed.

The rain sensor is built into an electronic LRSM which, in addition to detecting moisture on the windshield, enables the dusk function by measuring ambient light levels. According to this information and the sensitivity level set by the user, it controls both windshield cleaning and running lights.

OPERATION 

Operating front wiper/washer conditions.

Ignition switch status	Function that can be activated
OFF	Servicing position
ON	Front wiper Windshield washer circuit
START	Windshield wiper - cut-off Windshield washer circuit - cut-off Note:  If the rain sensor is present, automatic mode is selected by default during starting.

Courtesy of CHRYSLER GROUP, LLC

Wiper activation controls on the right stalk of the SCCM.

The windshield wiper functions can be activated via the controls on the right stalk of the SCCM.

Courtesy of CHRYSLER GROUP, LLC

The control on the right stalk of the SCCM is electrically connected to the BCM. The BCM receives MUX signals (different levels of resistance according to the position of the lever) from the right stalk of the SCCM.

The BCM controls the windshield wiper motor directly.

The BCM activates the electric motor of the washer pump circuit in accordance with the command from the right stalk of the SCCM.

Refer to COMPONENT INDEX .

Front Wiper/Washer Inputs:

• Front wiper request
• Washer request
• External temperature
• Remote start activity
• Front wiper cam info
• Washer fluid level
• Power mode status
• Ignition status
• Vehicle speed
• Auto start info
• Rain sensor level setting
• Rain sensor status

Front Wiper/Washer Outputs:

• Wiper status
• Rain sensor selections
• Wiper motor command
• Washer pump command
• Front wiper movement status
• Front wiper motor status
• SCCM status
• Washer fluid level low

Refer to COMPONENT INDEX .

The front wiper blades are moved back and forth across the glass by the front wiper arms when the wipers are being operated. The wiper blade flexor is the flexible member secured the length of the wiper blade element that evenly distributes the force of the spring-loaded wiper arm along the length of the element. The combination of the wiper arm force and the flexibility of the flexor makes the element conform to and maintain proper contact with the glass, even as the blade is moved over the varied curvature that may be encountered across the glass surface.

The rubber element is designed to be stiff enough to maintain an even cleaning edge as it is drawn across the glass, yet resilient enough to conform to the glass surface and flip from one cleaning edge to the other each time the wiper blade changes directions.

The front wiper arms are designed to mechanically transmit the motion from the wiper pivots to the front wiper blades. The front wiper arm must be properly indexed to the wiper pivot in order to maintain the proper wiper blade travel on the glass. The tapered mounting hole in the wiper arm pivot end interlocks with the serrations on the tapered outer circumference of the wiper pivot shaft, allowing positive engagement and finite adjustment of this connection.

The mounting nut locks the front wiper arm to the threaded stud of the wiper pivot shaft. The spring-loaded wiper arm hinge controls the down-force applied through the tip of the wiper arm to the front wiper blade on the glass. The receptacle on the tip of the wiper arm provides a cradle for securing and latching the wiper blade pivot block to the wiper arm.

Refer to COMPONENT INDEX .

The LRSM senses moisture and ambient light levels on the outside of the windshield glass and sends electronic messages to the BCM over the LIN data bus. The BCM relays messages back and forth between the LRSM and other electronic modules in the vehicle.

For the rain sensor function, InfraRed (IR) diodes within the LRSM generate infrared light beams that are aimed by the optics of the sensor through the windshield glass, while an IR photo diode monitors the infrared light reflected back from the windshield glass. When sufficient moisture accumulates within the wipe pattern on the windshield glass, less of the infrared light is reflected back and the sensor detects a change in the monitored infrared light intensity. For the light sensor function, an IR photo diode within the sensor monitors the intensity of the ambient infrared light received through the windshield glass and the sensor optics.

The internal programming of the LRSM sends the appropriate electronic wipe command  messages to the BCM over the LIN data bus. The BCM then responds by activating or deactivating the wiper system. Similarly, the LRSM provides electronic ambient light level  messages to the BCM, and the BCM relays these messages to other electronic modules in the vehicle.

The BCM microcontroller sends electronic wiper switch status  and automatic wipe sensitivity level  messages over the LIN data bus to the LRSM based upon the driver-selected settings of the control knob on the control stalk of the right (wiper) multifunction switch. The higher the selected wipe sensitivity setting the more sensitive the LRSM is to the accumulated moisture on the windshield glass, and the more frequently the LRSM will send wipe commands  to the BCM to operate the wiper system.

The LRSM operates on battery current received through a fused ignition output (RUN/Accessory) circuit. The LRSM has a path to ground at all times through a take out of the body wire harness with an eyelet terminal that is secured to the body sheet metal. Therefore, the LRSM is operational only when the ignition status is ON or Accessory.

If the BCM receives an electronic status message from the LRSM indicating a sensor failure condition, a Rain Sensor Failure  message should be displayed by the Instrument Panel Cluster (IPC). It is important to note that the default operation of the automatic wiper system is continuous wipe ON. Therefore, if no command message is received by the BCM from the LRSM for more than about five seconds when the Automatic wipe mode is selected, the wipers will default to Low Speed or High Speed continuous wipe operation. The BCM must be properly configured for the automatic wipers in order for this system to function.

Refer to COMPONENT INDEX .

The wiper (right) multifunction switch of the SCCM uses resistor multiplexing to control the many functions and features it provides using a minimal number of hard wired circuits. The switch receives clean grounds from the BCM, then provides resistor multiplexed return outputs to the BCM to indicate the selected switch positions. The BCM then sends hard wired control outputs as well as electronic switch status  messages over the CAN-C data bus to other electronic modules in the vehicle.

Refer to COMPONENT INDEX .

The washer pump features a reversible electric motor. The direction of the motor is controlled by hard wired outputs from the BCM. When battery current and ground are applied to the two pump motor terminals, the motor rotates in one direction. When the polarity of these connections is reversed, the motor rotates in the opposite direction. When the pump motor is energized, the rotor-type pump pressurizes the washer fluid and forces it through the appropriate pump outlet nipple and into the front or rear washer plumbing. The BCM controls the hard wired outputs to the pump motor based upon hard wired resistor multiplexed inputs received from the front and rear washer switch circuitry contained within the right (wiper) multifunction switch.

Washer fluid is drawn through the pump inlet nipple from the washer reservoir to the inlet port of the washer pump housing. An integral valve body is located in a housing on the outlet port side of the pump housing. A diaphragm in this valve body controls which washer system plumbing receives the washer fluid being pressurized by the pump. When the pump impeller rotates in a counterclockwise direction, the biased diaphragm is sealing off the rear washer system outlet and nipple so the pressurized washer fluid is pushed out through the pump front outlet port and the front washer outlet nipple. When the pump impeller rotates in a clockwise direction, pressurized washer fluid is pushed out through the pump rear outlet port and moves the diaphragm to open the rear washer outlet nipple and seal off the front washer outlet nipple, then the pressurized washer fluid is pushed out through the rear washer outlet nipple.

Refer to COMPONENT INDEX .

Washer fluid in the washer reservoir is pressurized and fed by the washer pump/motor unit through the front washer system plumbing and fittings to the two front washer nozzles. Whenever routing the washer plumbing or a wire harness containing washer plumbing, it must be routed away from hot, sharp, or moving parts; and, sharp bends that might pinch the plumbing must be avoided.

Refer to COMPONENT INDEX .

The washer fluid level sensor uses a float to monitor the level of the washer fluid in the washer reservoir. The float contains a small magnet. When the float moves, the proximity of this magnet to a stationary reed switch within the beam formation of the sensor changes. When the fluid level in the washer reservoir is at or above the float level, the float rises and the influence of the float magnetic field is applied to the reed switch causing the normally open reed switch contacts to close. When the fluid level in the washer reservoir falls below the level of the float, the float falls and the influence of the float magnetic field is removed from the reed switch, causing the contacts of the reed switch to open.

The washer fluid level sensor is connected to the vehicle electrical system through a dedicated take out and connector of the Front End Module (FEM) wire harness. The sensor is connected in series between the washer fluid switch sense and return circuits of the BCM. When the reed switch opens, the BCM senses the input on the washer fluid sensor return circuit. The BCM is programmed to respond to this input by sending an electronic message to the IPC over the CAN-C data bus requesting illumination of the low washer fluid indicator and the sounding of an audible chime tone warning.

Refer to COMPONENT INDEX .

The two front washer nozzles are designed to dispense washer fluid into the wiper pattern area on the outside of the windshield glass. Pressurized washer fluid is fed to each nozzle from the washer reservoir by the washer pump/motor unit through a single hose, which is attached to a barbed nipple on each washer nozzle below the hood panel. A fluidic matrix within the washer nozzle causes the pressurized washer fluid to be emitted from the nozzle orifice as an oscillating stream to more effectively cover a larger area of the glass to be cleaned.

The integral check valve in each nozzle 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 after the washer switch is actuated until washer fluid was dispensed through the nozzles, because the washer pump would have to refill the washer plumbing from the reservoir to the nozzles. Such a drain-back condition could also result in water, dirt, or other outside contaminants being siphoned into the washer system through the washer nozzle orifice. This water could subsequently freeze and plug the nozzle, while other contaminants could interfere with proper nozzle operation and cause improper nozzle spray patterns. In addition, the check valve prevents washer fluid from siphoning through the washer nozzles after the washer system is turned OFF.

When the washer pump pressurizes and pumps washer fluid from the reservoir through the washer plumbing, the fluid pressure unseats a diaphragm from over a sump well within the nozzle by overriding the spring pressure applied to it by a piston. With the diaphragm unseated, washer fluid is allowed to flow toward the nozzle orifice. When the washer pump stops operating, the spring pressure on the piston seats the diaphragm over the sump well in the nozzle and fluid flow in either direction within the washer plumbing is prevented.

Refer to COMPONENT INDEX .

The washer fluid reservoir provides a secure, on-vehicle storage location for a large reserve of washer fluid for operation of the front and the rear washer systems. The integral washer reservoir filler neck provides a clearly marked and readily accessible point from which to add washer fluid to the reservoir.

The reversible front and rear washer pump is located in a sump area near the bottom on the outboard side of the reservoir to be certain that washer fluid will be available to the pump as the fluid level in the reservoir becomes depleted.

Refer to COMPONENT INDEX .

The front wiper linkage module operation is controlled by the battery current inputs received by the wiper motor through the BCM. The wiper motor speed is controlled by current flow to either the low speed or the high speed set of brushes. An automatic resetting circuit breaker protects the motor from overloads.

The park switch is a single pole, single throw, momentary switch within the wiper motor that is mechanically actuated by the wiper motor transmission components. The park switch alternately closes the wiper park switch sense circuit to ground or to battery current, depending upon the position of the wipers on the glass. This feature allows the motor to complete its current wipe cycle after the wiper system has been turned OFF, and to park the wiper blades in the lowest portion of the wipe pattern.

The wiper motor crank arm, the two wiper linkage members and the two wiper pivots mechanically convert the rotary output of the wiper motor to the back and forth wiping motion of the wiper arms and blades on the glass.

The hard wired inputs and outputs of the front wiper system may be diagnosed using conventional diagnostic tools and procedures. Refer to the appropriate wiring information. However, conventional diagnostic methods will not prove conclusive in the diagnosis of the electronic controls and communication between other modules and devices that provide some features of the front wiper and washer system. The most reliable, efficient and accurate means to diagnose the front wiper system or the electronic controls and communication related to front wiper system operation requires the use of a diagnostic scan tool. Refer to the appropriate diagnostic information.