diagram LAND ROVER DISCOVERY 1999 Owner's Manual

BRAKES
70-2 DESCRIPTION AND OPERATION
Brake system control diagram

BRAKES
70-20 DESCRIPTION AND OPERATION
Operation
Refer to illustration.

+ BRAKES, DESCRIPTION AND OPERATION, Brake system control diagram.
When the ignition is switched on, the SLABS ECU performs a check of the brake related warning lamps as part of the
power up procedure. The warning lamps are illuminated for approximately 3 seconds and then extinguished. If a fault
warning lamp remains illuminated after the lamp check, a fault has been detected and repair action is required.
ABS
The ABS function prevents the road wheels locking during brake application, thus maintaining vehicle stability even
under emergency conditions.
WARNING: ABS is an aid to retaining steering control and stability while braking:
lABS cannot defy the natural laws of physics acting on the vehicle.
lABS will not prevent accidents resulting from excessive cornering speeds, following another vehicle too
closely, aquaplaning, etc.
lThe additional control provided by ABS must never be exploited in a dangerous or reckless manner
which could jeopardise the safety of driver or other road users.
lThe fitting of ABS does not imply that the vehicle will always stop in a shorter distance.
NOTE: During normal braking the feel of the brake pedal on vehicles equipped with ABS will be the same as that on
non ABS vehicles. During anti-lock braking operation the driver will experience feedback in the form of a pulsating
brake pedal and solenoid/pump motor noise from the ABS modulator.
The anti-lock braking function is automatically enabled whenever the ABS modulator is in the normal braking mode.
While the anti-lock braking function is enabled, if the SLABS ECU detects a wheel decelerating faster than the
average and at the calibrated wheel slip limit for ABS operation, it operates the ABS modulator in the ABS braking
mode for the affected wheel.
EBD
The EBD function optimises the distribution of hydraulic pressure between the front and rear axles, under all vehicle
load configurations and road conditions, to maintain vehicle stability during braking. EBD operates in forward and
reverse and is automatically enabled whenever the ABS modulator is in the normal braking mode at vehicle
deceleration rates of 0.3 g and above (i.e. medium to high brake pedal loads). EBD operation is similar to that of ABS,
but is calibrated to intervene at lower wheel slip limits and operates the brakes in axle pairs instead of individually.
During braking, if the SLABS ECU detects the wheels of one axle going slower than those of the other axle, i.e. a
potential wheel slip situation, it signals the ABS modulator to close the inlet solenoid valve for the brakes of the slower
wheels. This prevents any further increase in hydraulic pressure to those brakes, while allowing the hydraulic pressure
to the brakes on the other axle to increase and so maximise the overall braking effort. If the wheel speeds of the axle
being subjected to EBD control return within the calibrated wheel slip limits, the SLABS ECU signals a stepped
opening of the inlet solenoid valves, which allows a progressive increase of hydraulic pressure to the related brakes.
Operation of EBD is detectable from a stiffening of brake pedal movement as the inlet solenoid valves close and a
slight pulsing of the brake pedal as the inlet solenoid valves open. EBD operation ceases immediately the brake pedal
is released.
The wheel slip limit for EBD operation varies with vehicle speed. During normal operation, the inlet solenoid valves
always operate in axle pairs, with only one axle pair closed at any one time. Since the most lightly loaded wheel during
a braking manoeuvre will usually be the first to reach the slip limit, under most vehicle load configurations and road
conditions EBD control occurs on the trailing axle. However, EBD control can occur on the leading axle or switch
between axles during the braking manoeuvre.

RESTRAINT SYSTEMS
75-2 DESCRIPTION AND OPERATION
SRS block diagram
1DCU
2SRS warning lamp
3Driver airbag module4Driver seat belt pretensioner
5Passenger airbag module
6Passenger seat belt pretensioner

SEATS
76-5-2 DESCRIPTION AND OPERATION
Electric seat block diagram

SEATS
76-5-10 DESCRIPTION AND OPERATION
Heated seat block diagram (electric
seats)
1Passenger compartment fuse box
2Left seat heater switch
3Left seat heater module
4Left seat cushion heater element
5Left seat squab heater element 6Right seat heater switch
7Right seat heater module
8Right seat cushion heater element
9Right seat squab heater element

SUNROOF
76-6-4 DESCRIPTION AND OPERATION
System block diagram
1Passenger compartment fuse box
2BCU
3Sunroof ECU
4Front sunroof switch
5Front sunroof motor and microswitch6Rear sunroof - front switch
7Rear sunroof isolation switch
8Rear sunroof - rear switch
9Rear sunroof motor and microswitch

PANEL REPAIRS
PROCEDURES 77-2-13
PROCEDURES
General welding precautions
General
For ease of reference, the diagrams on the following pages show only the type of weld used in repair where it varies
from that used in production.
The replacement welds in the welding diagrams are denoted by the following symbols:
a = Single/Multiple thickness plug welds
b = MIG seam weld
When NOT carrying out welding operations the following criteria must be observed:
lWhere resistance spot welds have been used in production, these must be reproduced with new spot welds in
replacement where possible. All such reproduction spot welds must be spaced 30 mm (1.181 in) apart;
lWhen spot welding, it is recommended that test coupons of the same metal gauges and materials are produced
to carry out peel tests to ensure that welding equipment being used can produce a satisfactory joint. Plug welds
must be used if a satisfactory spot weld cannot be produced;
lThe electrode arms on hand-held spot welding guns must not exceed 300 mm (11.811 in) in length;
lSingle-side spot welding is not acceptable;
lBrazing and gas welding are not acceptable EXCEPT where they have been specified in production;
lWhere 3 metal thicknesses or more are to be welded together it is imperative to use MIG plug welds to ensure
joint strength;
lMIG plug welds must be used in repair joints where there is no access for a resistance spot welder. To replace
each production spot weld a hole must be drilled and/or punched, and a MIG plug weld then made in its place.
The number of plug welds must match exactly the number of spot welds which have been removed;
lWhere holes are left in an existing panel after removal of the spot welds, a single MIG plug weld will be made in
each hole as appropriate.
Seat belt anchorages
Seat belt anchorages are safety critical. When making repairs in these areas, it is essential to follow design
specifications. Note that High Strength Low Alloy (HSLA) steel may be used for seat belt anchorages.
Where possible, the original production assembly should be used, complete with its seat belt anchorages, or the cut
line should be so arranged that the original seat belt anchorage is not disturbed.
All welds within 250 mm (9.842 in) of seat belt anchorages must be carefully checked for weld quality, including
spacing of spot welds.

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

ALARM SYSTEM AND HORN
86-4-4 DESCRIPTION AND OPERATION
Alarm system block diagram
1Body Control Unit (BCU)
2Remote handset
3Receiver
4Fuel cut off switch
5Ignition switch
6Central door locking switch
7Volumetric sensors
8Bonnet activated alarm switch
9Drivers door key lock/unlock switches
10Door latch switches 11Fuel flap release switch
12Intelligent Driver Module (IDM)
13Battery Backed Up Sounder (BBUS)
14Alarm sounder
15Vehicle horns
16Direction indicators
17Door lock actuators
18Engine Control Module (ECM)
19Starter motor

WINDOWS
DESCRIPTION AND OPERATION 86-5-1
WINDOWS DESCRIPTION AND OPERAT ION
Electric windows block diagram
1Passenger compartment fusebox
2BCU
3LH front window switch
4LH front window motor
5RH front window switch
6RH front window motor
7Rear window lift relay8Centre console LH rear window switch
9LH rear door window switch
10LH rear door window motor
11Centre console RH rear window switch
12RH rear door window switch
13RH rear door window motor
14Rear window isolation switch