Part 2
Wipers and Washers
RAIN/LIGHT SENSOR
The rain/light sensor is located at the upper edge of the windscreen, behind the interior rear view mirror. The sensor is mounted on an optical unit, which is heat bonded to the inner surface of the windscreen during manufacture. If damage occurs to the optical unit or the windscreen, then a new windscreen will be required and installation can only be performed by an authorized Land Rover dealer.
The rain sensor must be re-initialized to a new windscreen, if fitted, or if transferred to another vehicle, the new rain sensor assembly will automatically re-initialize when powered-up for the first time. In order for this to occur successfully it must be fitted and connected to the optical filaments (bonded to the screen assembly).
The rain/light sensor unit attaches to the optical unit via two clips, which latch onto formed tags on the optical unit. Positive retention is achieved by two retaining clips, which force the clips onto the tags. The retaining clips must be withdrawn to facilitate sensor removal.
The sensor provides information to the CJB for the optimum wiper operation for the prevailing conditions to maintain the screen in a clear condition at all times. The rain/light 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.
Rain Sensor Functionality
The rain/light sensor contains transmitter and receiver diodes, which transmit and receive infrared light, which is directed onto the windscreen via an optical unit. The light is directed at an angle so that the light is reflected 100% on the outside surface of the screen and is transmitted back into the optical unit. To receive a 100% reflection, the outer screen surface must be clean and dry.
The rain/light sensor is active when the wiper column control switch is in the intermittent position. The rain/light sensor suspends wiper operation when the area of the windscreen for the rain/light sensor is dry and operates the wipers continuously when the windscreen is subject to heavy rainfall.
The sensitivity of the rain/light sensor can be adjusted by the driver using the intermittent rotary switch on the wiper stalk. Six sensitivity levels of the sensor can be selected, which has the effect of increasing or decreasing the wiper delay period, allow driver adjustment for the prevailing conditions. When several continuous wipe cycles have taken place, the sensor will maintain the continuous operation to avoid switching back to intermittent from a continuous wipe and back again.
The rain/light sensor receives vehicle speed information from the Anti-lock Braking System (ABS) module on the Local Interconnect Network (LIN) bus via the CJB. The sensor increases the sensitivity as the speed increases to optimize wiper operation. When the vehicle speed is reduced to less than 5 mph (8 km/h), the sensitivity is automatically reduced. Below this speed the wipers will only operate continuously in very heavy rain.
Automatic Headlamp Operation
A light sensor is incorporated in the housing of the rain/light sensor 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 rain/light sensor. 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 front and rear wiper functions.
The switch comprises 8 switch positions and the intermittent rotary control. The switch positions each complete a combination of earth paths to connections on the CJB. The CJB interprets the selected combination of switches and operates the respective function accordingly.
Flick Wipe
Moving the switch down selects the front wiper flick wipe function. The front wipers will operate at fast speed for as long as the flick wipe switch position is operated. Once the switch is released the front wiper motor will revert to a normal (slow) speed operation until a park position has been detected.
Intermittent
Moving the switch up one position from 'OFF', selects intermittent front wiper operation. The rotary potentiometer on the stalk selects one of six delay periods. 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 control module. The selected delay period decreases with an increase in road speed. When a rain/light sensor is incorporated into the system, the intermittent position also initiates wiper operation controlled by the rain/light sensor. The sensitivity of the rain/light sensor is also adjusted by rotating the rotary switch to one of the six positions.
The rotary switch selects differing output values for each position. The switch is wired to three data input terminals of the CJB.
The time delay periods for the vehicle stationary and when moving at different speeds are shown in seconds (by speed CLASS) in the following tables:
Key:
- < = Less than
- > = Greater than.
The rotary switch positions also influence the operation of the rain/light sensor (when fitted) by adjusting its sensitivity. Refer to the Rain/Light Sensor section for details.
Normal (Slow) Speed
The normal (slow) speed continuous wiper operation is selected by moving the switch vertically to the second detente position from 'OFF'. The wipers will operate continuously when the vehicle is moving. When the vehicle is stationary, or less than 5 mph (8 km/h), the CJB operates the wipers in the intermittent mode (if speed dependant wipe mode is configured), using a 3 second intermittent delay period.
Fast Speed
The fast speed continuous wiper operation is selected by moving the switch vertically to the third detente position. The wipers will operate continuously at fast speed when the vehicle is moving. When the vehicle is stationary, or less than 5 mph (8 km/h), the CJB operates the wipers in normal (slow) speed mode (if speed dependant wipe mode is configured).
Wash/Wipe
When the non-latching wiper stalk button is pushed the front screen washer is operated. If the wipers are off and the button is pressed for less than 0.5 seconds, only the washer will operate. If the button is pressed for more than 0.5 seconds, the wipers will come on and perform two wipes. When headlamp washers are fitted, the headlamp washers will operate if the front windscreen washer is operated and the headlamps are on - refer to headlamp wash section for detail of operation. The CJB monitors the wash/wipe switch operation and after the switch is released, if a programmed wipe is enabled, the CJB allows two further wipe cycles to be completed.
Rear Wash/wipe
Moving the switch rearwards, towards the driver, selects the intermittent rear wash/wipe function. The intermittent delay period will vary according to the sensitivity settings and vehicle speed.
When the switch is moved rearwards to the second position and held, the washer pump will operate. If the switch is operated for more than 10 seconds, the pump will be disabled. When the switch is released, the rear wiper will complete a further two full wipe cycles and then operate on an intermittent function until selected off.
HEATED WINDSCREEN WASHER JETS
Two windscreen washer jets are located in the rear trim panel on the bonnet outer surface. The washer fluid feed hose from the front screen pump is connected to a 'Y' piece connector located between the two jets. Two short lengths of hose connect the jets to the 'Y' piece. Each jet contains a NRV 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 two ball nozzles, which can rotate in their housing's to obtain the optimum fluid application onto the windscreen. Each washer jet contains a heater element, which prevents the fluid freezing in the nozzles in very cold conditions and a Positive Temperature Coefficient (PTC) sensor, which regulates the temperature. The jet heater elements are controlled by the Automatic Temperature Control Module (ATCM) and a heated washer jet relay in the BJB. For additional information, refer to Control Components
REVERSE GEAR INPUT
The intermittent delay period (below) depends on speed dependant wipe mode being enabled or disabled.
The rear wiper also operates if reverse gear is selected and the front wipers are on. If the front wipers are operating continuously when reverse is selected, the rear wiper will also operate continuously as long as reverse gear is engaged. If the front wipers are operating intermittently when reverse is engaged, the rear wiper will complete one wipe cycle then wipe intermittently.
On vehicles fitted with rain/light sensor, when reverse gear is selected while the front wipers are in intermittent mode but the rain/light sensor indicates that the front wipers are off, the rear wiper will not operate. If the rain/light sensor subsequently calls for a single wipe, the rear wiper will operate a single wipe cycle. If the rain/light sensor calls for a slow or fast wipe, the rear wiper will operate continuously.
The CJB will operate the rear wiper (providing the front wipers are on) upon receipt of a reverse gear signal from the Electronic Automatic Transmission (EAT) module on the CAN bus, via the instrument cluster. On vehicles with manual transmission, the gear position signal is transmitted directly from the transfer box control module and picked by the CJB as an CAN bus message, via the instrument cluster.
'TAIL GATE OPEN' DISABLE
If the rear wiper is switched on or is already running and the tail gate is opened, the rear wiper should not start to run, or should immediately become disabled during a wipe cycle. If the tail gate is subsequently closed, the wiper will resume its normal operation after a delay of three seconds. Should the vehicle speed input be more than 4 mph (6km/h), then the tail gate switch will be deemed as closed.
The CJB receives the 'tail gate open' signal directly from the upper tail gate central locking motor.
FRONT AND REAR 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 position 0 and back to position I. 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 can only be reset by turning the ignition off.
The rear wiper algorithm contains the same logic as mentioned above.
DIAGNOSTICS
The diagnostic socket allows the transfer of information between the CJB, the rain/light sensor and T4. The diagnostic socket is located in the lower fascia closing panel, on the driver's side, below the steering column.
The rain/light sensor performs an internal self-test in the first 50ms 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/light 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/light sensor fault prevents the sensor from operating, the CJB will control wiper operation as if a rain/light 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 LIN bus. If a fault is detected, a code applicable to that fault is stored in a fault log. Two fault logs are provided within the CJB for internal and external faults.
CONTROL DIAGRAM
