Wiper and Washer Systems: Description and Operation

Wipers and Washers

COMPONENT LOCATION









INTRODUCTION
The wipers have 2 speed controls, normal and fast, and an intermittent wipe mode. The wipers will park automatically irrespective of their position, when the ignition is in the 'Off' mode or the control switch is selected.
A timed washer jet function eliminates the trail of washer fluid left on the windshield after a wiping action and reduces fluid consumption by only operating the washer jets on the up stoke of the wiper arms.
Within the wiper and washer system the following features can be attained:
- Adjustable interval intermittent wiping
- Speed dependant wiping
- Programmable wash and wipe sequencing
- Automatic moisture sensitive wiping (rain sensor).
Moisture sensitive wiping will be initiated when the vehicle is running and not in the PARK or NEUTRAL gear position. The wiper switch must be in the AUTO position.
The Central Junction Box (CJB) controls the system and features.

CENTRAL JUNCTION BOX (CJB)
The CJB is an integrated unit located behind the instrument panel on the passenger side of the bulkhead. The CJB contains fuses, relays and a number of microprocessors, which control the power supply and functionality of the wash/wipe system and other vehicle systems.

Inputs and Outputs
The CJB receives and sends the following wiper and washer system inputs and outputs:

Inputs
- Intermittent wipe switch
- Rain sensor, if fitted
- Normal (slow) speed continuous switch
- Fast speed continuous switch
- Flick wipe switch
- Wash switch
- Stop/start switch
- Lighting switch
- Low level reservoir status, via Medium Speed (MS) CAN bus
- Vehicle speed, via MS CAN bus
- Wiper motor park switch
- Ambient temperature, via MS CAN bus

Outputs
- Wiper motor (normal)
- Wiper motor (fast)
- Windshield washer pump
- Heated washer jets (if fitted)
- Headlamp power wash pump

WIPER ASSEMBLY
The wiper assembly comprises:
- Wiper motor and linkage assembly
- Wiper arms and blades (washer jets located on wiper arms)

Wiper Linkage









The wiper linkage and motor assembly are available as separate components. The wiper linkage and motor differs between LH and RH drive models.
The assembly is located below the leafscreen in the engine compartment and is secured with bushes, sleeves and bolts. The rubber bushes isolate the assembly from the body mountings.
The linkage assembly comprises a main tube, with a spindle housing at each end. The motor is attached directly to the passenger side spindle housing. A motor crank is positively attached to the motor output shaft. One link rod links the motor crank to the passenger spindle crank. The other link rod links the driver spindle crank to the passenger spindle crank. Drive is supplied from the motor to the driver spindle crank and then to the passenger spindle crank.
The motor crank converts rotary motion from the motor output shaft into linear movement of the link rods. The cranks, connected between the each link rod and spindle housing, convert the linear motion to reciprocating motion at the spindle housing. This reciprocating motion is passed to the wiper arms and blades causing the blades to wipe an arc across the windshield.

Wiper Motor
The motor assembly comprises a dc motor, which drives a gear wheel via a worm drive attached to the motor spindle. The gear wheel has a central spigot, which provides the attachment point for the motor crank.
A 5 pin connector (only 4 are used for this application) connects the motor electrically. The connector supplies 2 battery voltage feeds to the motor (when switched). The motor has 3 sets of brushes with one brush connected to ground. One feed is direct to the motor brush opposite the ground brush and operates the motor at normal (slow) speed. The second feed is connected to a motor brush, which is offset from the ground brush and operates the motor at fast speed. With the power supplied through this brush, the current flows through fewer coil windings. This results in a lower resistance to the current flow to the ground brush and gives a higher motor rotational speed.
Output control of the wiper motor is through a double contact relay. The relay is located in the Battery Junction Box (BJB).
The motor has an internal track switch, which signals the CJB when the wipers have reached the park position. The park signal is closed circuit when the wipers are in the park position. When the wipers are switched off and the CJB receives the park position signal from the motor, the CJB shorts the motor via a relay bridge circuit. This short circuit has the effect of applying a brake to the motor, giving precise positioning of the wiper blades in the park position.

Wiper Arms
The wiper arms are positively located on tapered splines on the wiper linkage spindles.
The wiper arm has a spindle point, midway between the spindle attachment and the blade. A tension spring is connected to the wiper arm on each side of the spindle point and applies pressure to maintain the wiper blade in contact with the windshield.
The wiper blades are attached to the wiper arms with clips that allow the blade to pivot. The wiper blades comprise a sprung steel curved backbone which applies pressure evenly to the windshield, to which is applied the wiping lip to the bottom surface. An aerofoil section presses the blades onto the windshield at high vehicle speeds.

WASHER RESERVOIR AND PUMPS









The plastic, moulded reservoir is located in the RH wheel arch, behind the liner and has a capacity of 13.3 pints (6.3 liters). It is secured to the body and front panel with bolts. A boss on the reservoir locates into a bracket mounted off the A-pillar casting and provides additional support.
The reservoir has 2 recessed holes on its front face, which provide location for the windshield and headlamp washer pumps. The pumps are push fitted into grommets, which seal the pumps in their locations. A hole in the top of the reservoir allows for the fitment of the filler neck. The windshield washer fluid hose is integrated into the harness and so follow it's routing. The headlamp washer hose, from the reservoir, is routed over the wheel and across the body between the headlamps.
A hole with a grommet in the side of the reservoir provides the location for the fluid level sensor.
The low level sensor has a float, with integral magnet. The sensor has a contact, which is normally open when the reservoir is full. When the fluid level reduces to approximately 1 litre, the magnetic float pivots down, which causes the switch contact to close. This closed circuit is sensed by the instrument cluster, which displays the low fluid level message and transmits the switch status on the medium speed CAN bus.
The instrument cluster monitors the fluid level sensor continuously. The instrument cluster checks the fluid level sensor when the ignition is switched on to give the driver an early warning of the low fluid level. The instrument cluster then monitors the sensor value over a 25 second period when the ignition is on to prevent invalid messages due to fluid 'sloshing' in the reservoir.
When a low fluid level signal is transmitted to the instrument cluster, a 'WASHER FLUID LOW' message is displayed in the instrument cluster's message centre. The first display of this message, or illumination of the indicator, is accompanied by a 'chime' sound to alert the driver to the low fluid level.

Windshield Washer Jets
A windshield washer jet is located on each wiper arm. The washer fluid feed hose from the windshield pump is connected to a 3-way valve connector located between the 2 jets. The 3-way valve acts to prevent washer fluid draining back to the reservoir and also to limit the amount of washer fluid, which can be forced by gravity from the jet during cornering.
Each washer jet has a fan jet, which directs the washer fluid long the length of the wiper blade and a pencil jet, which sprays washer fluid to the heal on the wiper blade to ensure good distribution of fluid. For additional information, refer to Control Components Control Components

HEADLAMP WASHERS









The headlamp washer assembly is located below each headlamp.
The headlamp washer operation is controlled by the CJB via a headlamp washer relay. The relay is located in the BJB.

RAIN SENSOR









The rain sensor is located at the upper edge of the windshield, behind the interior rear view mirror. The sensor is mounted with a clip onto a collar, which is bonded to the inner surface of the windshield during manufacture. If damage occurs to the collar or the windshield, then a new windshield will be required and installation can only be performed by an authorized Jaguar dealer.
The rain sensor is secured to the collar and windshield with a metal clip, which latches onto formed tags on the collar.
The sensor provides information to the CJB for the optimum wiper operation for the prevailing conditions to maintain the shield in a clear condition at all times. The rain sensor is an optical unit, which operates on an infrared waveband. The sensor uses the principle of the laws of reflection on interfacing surfaces between materials with differing refraction properties.

Automatic Headlamp
A separate light sensor is incorporated in a instrument panel-mounted housing to control the operation of the automatic headlamps.
The automatic headlamps will function when the lighting control switch is in the 'AUTO' position and the CJB receives a 'lights on' signal from the sensor (information distributed to the CJB via medium speed CAN bus messages). For additional information, refer to Exterior Lighting

WIPER CONTROL COLUMN SWITCH









The wiper control column switch is located on the right hand side of the steering column and controls all wiper functions. The wipers only operate with the ignition in the 'On' mode.
The switch comprises 5 switch positions and the intermittent rotary control. The switch positions each complete a combination of ground paths to connections on the CJB. The CJB interprets the selected combination of switches and operates the respective function accordingly.
The rotary potentiometer on the stalk selects 1 of the delay periods for the intermittent wipe function. The delay period is also influenced by vehicle speed (should speed control intermittent wipe mode be configured), using a signal value derived from the ABS module. The selected delay period decreases with an increase in road speed. When a rain sensor is incorporated into the system, the intermittent position also initiates wiper operation controlled by the rain sensor.
For more information on wiper and washer operation refer to the owners handbook.

CONTROL DIAGRAM

NOTE:
A = Hardwired: N = Medium Speed CAN bus









PRINCIPLES OF OPERATION

Headlamp Washers
The headlamp washers are only active when the headlamps and ignition are switched on. If the washer reservoir fluid level becomes low, the instrument cluster sends a message, via the medium speed CAN bus, to the CJB, which suspends headlamp wash operation to preserve washer fluid in the reservoir.
With the ignition and lights on, headlamp wash is activated on the first operation of the wiper column control switch in the wash/wipe position.
The CJB monitors the operation of the wash/wipe switch and maintains a counter to restrict headlamp washer operation to every fourth operation of the wash/wipe switch in conjunction with a 10-minute timer. The timer prevents a second operation of the headlamp washers within a 10-minute period. Should the washer switch be activated for more than 4 programmed wipe requests during the 10-minute period, the headlamp washer will remain disabled. Only the next consecutive programmed wipe request, after the 10-minute timer has expired, will the headlamp washers be enabled. The counter and timer are reset when the ignition is set in the 'Off' mode or the light switch is turned from OFF back to ON within the same ignition cycle.
When headlamp wash is active, the CJB energizes the washer pump twice per cycle. The headlamp washer pump is powered for 2 x 800 ms periods.

Rain Sensor









The rain sensor contains transmitter and receiver diodes, which transmit and receive infrared light. This is directed onto the windshield via an optical element. The light is directed at an angle so that light is reflected 100% on the outside surface of the shield and is transmitted back into the optical unit. To receive a 100% reflection, the outer shield surface must be clean and dry.
The rain sensor is active when the wiper column control switch is in the intermittent position. The rain sensor suspends wiper operation when the area of the windshield for the rain sensor is dry and operates the wipers continuously when the windshield is subject to heavy rainfall.

Automatic Headlamp
A separate light sensor is incorporated in a instrument panel-mounted housing to control the operation of the automatic headlamps.
The automatic headlamps will function when the lighting control switch is in the 'AUTO' position and the CJB receives a 'lights on' signal from the sensor (information distributed to the CJB via medium speed CAN bus messages). For additional information, refer to Exterior Lighting

Wiper Motor Blocking Protection
The wiper park signal is also used by the CJB for blocking protection of the front wiper motor. This feature protects the motor in the event of the wiper operation being obstructed.
If the CJB does not receive a wiper park signal status change for a period of 6 seconds, when the wiper motor is active, the CJB removes the power supply to the motor. The motor will remain disabled until either an alternative motor mode has been selected, or the ignition has been moved to the 'Off' mode and back to the 'Accessory' mode. Should a stall condition be achieved 3 times during a single ignition position I status, then the wiper relay will remain disabled, regardless of wiper switch positions, for 180 seconds. The CJB will not automatically switch the motor on, to prevent the risk of injury. The wiper switch must be moved off and then on to reactivate the wiper motor. The blocking protection is active in all wiper switch positions and will automatically be reset when the ignition enters the 'Off' mode.

Diagnostics
The diagnostic socket allows the transfer of information between the CJB and the Integrated Diagnostic System (IDS). The diagnostic socket is located in the lower instrument panel, on the driver's side, below the steering column.
The rain sensor performs an internal self-test from the ignition being switched to position I and can store fault codes, which can be used to diagnose, faults or non-function of the rain sensor. The faults are stored in a non-volatile memory, which retains the logged fault codes even when the power supply is disconnected. If a rain sensor fault prevents the sensor from operating, the CJB will control wiper operation as if a rain sensor is not installed in the system.
The CJB monitors all inputs and outputs relative to the wiper system and other CJB controlled functions on the Local Interconnect Network (LIN) bus. If a fault is detected, a code applicable to that fault is stored.