LAND ROVER DISCOVERY 2002 Workshop Manual

AIR CONDITIONING
82-48REPAIRS

WIPERS AND WASHERS
DESCRIPTION AND OPERATION 84-1
WIPERS AND WASHERS DESCRIPTION AND OPERAT ION
Wipers and washers component layout
RHD shown, LHD similar
1Headlamp power wash relay
2Passenger compartment fuse box (rear wiper
relay, front wiper relay and IDM)
3Variable Delay Switch
4Front wash/ wipe switch
5Rear wiper motor
6Rear washer switch7Rear wiper switch
8Body Control Unit (BCU)
9Front washer pump
10Rear washer pump
11Front wiper motor assembly
12Headlamp power wash pump

WIPERS AND WASHERS
84-2 DESCRIPTION AND OPERATION
Front wiper components
1Linkage assembly
2Wiper motor
3Stud plate
4Gasket
5Wheel box 2 off
6Bolt 2 off
7Earth strap
8Cover plate9Bolt 3 off
10Lock washer
11Nut
12Flanged nut 5 off
13Wiper blade 2 off
14Cover
15Nut
16Wiper arm 2 off

WIPERS AND WASHERS
DESCRIPTION AND OPERATION 84-3
Rear wiper components
1Wiper blade
2Washer jet
3Washer
4Seal
5Washer 2 off
6Lock washer 2 off
7Bolt 2 off8Wiper motor
9Nut
10Nut
11Cover
12Wiper arm
13Washer tube

WIPERS AND WASHERS
84-4 DESCRIPTION AND OPERATION
Washer components
Reservoir with headlamp power wash shown

WIPERS AND WASHERS
DESCRIPTION AND OPERATION 84-5
1Windscreen washer jet 2 off
2Elbow 3 off
3In-line non-return valve
4Tube
5'T' connector
6Tube
7Connector
8Filler neck tube
9Filter
10Cap
11Bracket
12Level float
13Filler neck seal
14Bolt
15Reservoir
16Pump sealing grommet (if fitted)
17Powerwash pump (if fitted)18Clip
19Tube
20Screw 2 off
21Powerwash jet 2 off
22Clip 4 off
23Tube
24'T' connector
25Tube
26Nut 2 off
27Pump sealing grommet 2 off
28Rear washer pump
29Front windscreen washer pump
30Elbow 2 off
31Tube - front windscreen
32Tube - rear tail door window
33Non-return valve

WIPERS AND WASHERS
84-6 DESCRIPTION AND OPERATION
Wipers and washers block diagram

WIPERS AND WASHERS
DESCRIPTION AND OPERATION 84-7
1BCU
2IDM
3Front wiper relay
4Front wash / wipe switch
5Front wiper motor assembly
6Front washer pump motor
7Variable delay switch
8Rear wiper relay
9Rear wiper switch
10Rear washer switch
11Rear wiper motor
12Rear washer pump motor
13Headlamp power wash relay
14Headlamp power wash pump motor

WIPERS AND WASHERS
84-8 DESCRIPTION AND OPERATION
Description
General
All markets have a common wiper system with headlamp powerwash as an option.
The wipers system comprises two front wipers and one rear wiper which are powered by electric motors. A washer
reservoir is located in the front left hand wheel arch and is fitted with two electric pumps. Each pump supplies washer
fluid to either the front or rear screens. On certain models, a third pump can be fitted to operate a headlamp power
wash function. Operation of the front and rear wipers and washers is controlled by the driver using switches located
on a steering column stalk and push button switches on the fascia.
Control of the wipers and washers is achieved by the following components:
lBCU.
lIDM.
lFront wiper relay.
lFront wash/ wipe switch.
lVariable delay switch.
lFront wiper motor assembly.
lFront washer pump motor.
lRear wiper relay.
lRear wiper switch.
lRear washer switch.
lRear wiper motor.
lRear washer pump motor.
Both the Body Control Unit (BCU) and the Intelligent Driver Module (IDM) control the wiper system. The BCU controls
the time delay function of the wiper system and is located below and behind the passenger glovebox. During engine
cranking the BCU prevents wiper functions. Two relays are located in the passenger compartment fusebox. The
relays control the delay operation of the front and rear wipers. The relays are an integral part of the fusebox and
cannot be renewed separately.
Power for the wiper system is supplied by the IDM, which is integral with the passenger fusebox and cannot be
renewed as a component. A serial communication link allows communication between the IDM and the BCU.
The system has diagnostic capabilities through TestBook.
Front wipers
The two front windscreen wipers are operated by a linkage assembly and an electric motor located under the plenum
grill below the windscreen. The linkage and motor assembly is handed for left and right hand drive vehicles. The motor
is an integral part of the linkage and cannot be replaced separately.
The linkage comprises a pressed steel mounting plate which provides for the attachment of a wheel box at each end.
The mounting plate is secured to the bulkhead with flanged nuts which attach to a stud plate located behind the
bulkhead. A link arm is attached to each wheel box by a short link and secured with circlips. The link arm has an
attachment hole centrally located along its length for the electric motor drive link.
The electric motor is mounted in a recess in the bulkhead below a sealed cover plate. The drive spindle of the motor
protrudes through the cover plate and is fitted with a link. The link is attached to a tapered spline on the motor spindle
and is secured with a lock washer and nut. The opposite end of the link is attached to the central attachment point on
the link arm and secured with a circlip.
Each wheel box has a taper splined shaft which allows for the attachment of the wiper arm which is secured with a
washer and nut. The shaft of each wheel box is passed through a rubber sealed aperture in the plenum. The wiper
arm attachment to the splined shaft has a pivot to which the remainder of the arm is attached. The two parts of the
arm are connected by a spring which controls the pressure of the blade on the screen to a predetermined amount.

WIPERS AND WASHERS
DESCRIPTION AND OPERATION 84-9
The wiper blades are attached to the wiper arms with a clips that allow the blade to pivot. Each wiper blade comprises
a number of levers and yokes to which the rubber wiper is attached. The levers and yokes ensure that the pressure
applied by the arm spring is distributed evenly along the full length of the blade. The rubber wiper is held in the yokes
by a pair of stainless steel strips which also contribute to the even distribution of spring pressure along the blade. The
driver's side wiper blade is fitted with an aerofoil which presses the blade onto the screen at high speed. This prevents
the blade from lifting off the screen and maintains the wiping performance.
Front wash/ wipe switch
The front wash/ wipe switch is located on a stalk on the RH side of the steering column and allows the driver to control
the operation of the front wipers and the front washer pump.
Operating the washer switch provides battery voltage from fuse 19 in the passenger compartment fusebox to the
washer pump motor.
Operating the flick wipe function provides battery voltage from fuse 19 in the passenger compartment fuse box to the
high-speed brushes of the wiper motor.
Operating the intermittent function provides a battery voltage signal to the BCU. The BCU determines the wipe
interval from the variable delay switch and signals the IDM to activate the front wiper relay, which provides battery
voltage to the wiper motor.
Operating the low-speed function provides battery voltage from fuse 19 in the passenger compartment fuse box to
the low-speed brushes of the wiper motor.
Operating the high-speed function provides battery voltage from fuse 19 in the passenger compartment fuse box to
the high-speed brushes of the wiper motor