7 Windshield washer pump 8 Wiper/Washer switch - RH (right-hand) steering column multifunction switch 9 Instrument cluster 10 CJB (central junction box) 11 BJB (battery junction box)
WINDSHIELD WIPERS System Operation
Operation of the wipers and washers is controlled by the CJB in response to driver inputs from the wiper control switch and signals from the rain/light sensor. The instrument cluster monitors the condition of the wiper/washer control switch and
transmits driver requests to the CJB over the medium speed CAN bus.
The wiper control switch is connected via hardwired connections to the instrument cluster. The instrument cluster outputs on 4
wires a reference voltage to the wash/wipe switch, the auto wiper switch, the wiper switch and the flick wipe switch. All the
switches are connected to the instrument cluster on a common ground. Each switch function is connected to ground via a
resistor or series of resistors and the instrument cluster monitors the ground signal and determines which function has been
selected. The instrument cluster then outputs the appropriate message on the medium speed CAN bus to the CJB which responds to the requested wiper function. The CJB then activates the appropriate function either directly or via relays in the EJB for the wipers and headlamp powerwashers. Speed Dependent Mode
When the wipers are operating, a vehicle speed signal received by the CJB on the high speed CAN bus is used to operate a speed dependent mode. If the wipers are in fast wipe and the vehicle speed decreases to below 2 km/h (1.2 mph), the wipers
will reduce to the normal wipe speed. When the vehicle speed increases to above 8 km/h (5 mph) the fast wiper speed
selection is restored. If slow speed is selected and the vehicle speed drops below 2km/h (1.2 mph), the wipers will operate in
the intermittent mode. When the vehicle speed increases to above 8 km/h (5 mph) the slow wiper speed selection is restored
– this feature is configurable by the dealer using the approved Jaguar diagnostic system.
Wiper Motor
The wiper motor is controlled by the CJB. The CJB is connected to a wiper motor normal/fast relay in the EJB on 2 wires. The CJB is also connected to a wiper run/park relay, also located in the EJB.
Driver requests are received by the CJB which energizes the wiper motor normal/fast relay in the appropriate mode (normal or fast wipe) and also energizes the run/park relay in the run mode by providing a ground for the relay coils. When wiper
operation is deselected by the driver, the CJB monitors a park switch which is integral with the wiper motor. On receipt of a signal from the park switch, the CJB de-energises the run/park relay, removing the power supply through the normal/fast relay, stopping the wipers in the park position on the windshield.
The wiper motor is a DC (direct current) motor which drives a gear wheel via a worm drive attached to the motor spindle. The
motor has 3 sets of brushes with one brush connected to ground. When the normal/fast relay is energized in the normal
position, a power feed is supplied to the brush directly opposite the ground brush and operates the motor at slow speed.
When the relay is energized in the fast position, a power feed is connected to the second motor brush, which is offset from the
ground brush and operates the motor at the fast speed. With power supplied through the offset brush, the current flows
through fewer motor coil windings. This results in a lower resistance to current flow to the ground brush and produces a higher
motor rotational speed.
WINDSHIELD WASHERS
The windshield washers are controlled by the CJB. A driver request for washer operation, via the wiper control switch, is passed to the instrument cluster on the LIN bus. The instrument cluster passes the message to the CJB on the medium speed CAN bus.
The CJB energizes the windshield washer pump during the up stroke of the first 2 wash/wipe cycles. This ensures that wiper fluid is pushed to the sides of the windshield and eliminates the trail of fluid which can occur if the fluid is pushed to the
bottom of the windshield. The wipers will continue for 3 more cycles, followed after a delay of 4 seconds, by a single dry wipe.
NOTE: The dry wipe feature is configurable using an approved Jaguar diagnostic system.
The operation of the washer pump on the wiper up stroke only is configurable using an approved Jaguar diagnostic system.
The washer button can be pressed and held and the wipers will operate continuously for up to 10 seconds. After this period
when the button is released, the wipers will continue for 3 more cycles, followed after a delay, by a single dry wipe. After this
period washing will be inhibited, the wipers will continue for 3 more cycles, followed after a delay, by a single dry wipe.
Reactivating the switch will recommence the wash/wipe cycle.
RESERVOIR LEVEL SWITCH
The level switch is connected directly to the CJB. The switch is operated by a float which closes contacts within the switch when the fluid level falls to below the switch level. When the contacts are closed a ground path is completed from the CJB through the switch. This is sensed by the CJB which issues a message to the instrument cluster which displays a low fluid level warning.
HEADLAMP POWERWASHERS
The headlamp powerwash is activated when the driver requests windshield washer operation. The CJB receives the driver request via a CAN bus message from the instrument cluster. The CJB then checks for an exterior lights active signal and that a low washer fluid level signal is not present.
The CJB outputs a control voltage to a headlamp powerwash pump relay located in the EJB. The relay is energized by the CJB for a pre-determined period to allow the headlamp telescopic washers to operate.
The CJB monitors the driver washer requests and only operates the headlamp powerwash on every fourth request for windshield washer operation, provided that 10 minutes have elapsed since the last headlamp powerwash operation. The
powerwash sequence is reset when the headlamps or the ignition is switched off.
NOTE: If a low fluid reservoir level is present the CJB prohibits headlamp powerwash.
RAIN/LIGHT SENSOR
On receiving a request for automatic windshield wiper operation, the CJB interprets LIN bus messages received from the rain sensor. The rain sensor provides LIN bus messages with values ranging from 0 to 7.
A signal value of 0 is interpreted by the CJB as the windshield is dry. A signal value from 1 to 5 is interpreted by the CJB as a small amount of water hitting the windshield. In this instance, the CJB initiates a slow wipe. A signal value of 7 is interpreted by the CJB as a large amount of water hitting the windshield. In this instance, the CJB initiates a fast wipe. NOTES:
The CJB will only change a fast wipe routine to a slow wipe routine if the rain sensor value is lower than 7.
A = Clean and dry windshield; B = Wet and dirty windshield
Item Description 1 Windshield outer surface 2 Optical element 3 Transmitter diodes (100% light transmitted) 4 Rain sensor
