1995 LAND ROVER DISCOVERY anti lock

BRAKES
3
DESCRIPTION AND OPERATION Description of components
1. ABS Modulator unit
To provide the ABS function a Modulator is positioned
within the system between the master cylinder and the
calipers. On both LHD and RHD vehicles it is sited on
the left inner wing [fender]. The Modulator has 8
solenoid valves, 2 for each wheel, 2 expanders and a
recirculation pump. It is non serviceable.
2. Servo/master cylinder
Actuation of the system is provided by a combined
master cylinder and servo assembly attached to the
pedal box, this provides pressure to opposed piston
calipers at each brake pad Twin piston at the front
axle, single piston at the rear.
3. Pressure reducing valve
To maintain the braking balance, pressure to the rear
axle is regulated by a Pressure Reducing Valve (PRV)
This PRV is of the failure bypass type, allowing full
system pressure to the rear axle in the event of a front
circuit failure. It is sited on the left inner wing [fender].
4. Electronic control unit - ECU
ABS control is provided by an electronic control unit
which is positioned on the passenger side of the
vehicle behind the dash panel/glove box.
The ECU, which is non-serviceable, is connected to
the ABS harness by a 35 way connector. non
serviceable.
The ECU continually monitors the brake system,
providing diagnostics in the event of a system
malfunction. Details of how to access the ECU
diagnostics are provided in the Electrical
Troubleshooting Manual.
5.& 6. Front and rear sensors/exciter rings - 4 off
A sensor is sited at each wheel, sensing a 60 tooth
exciter ring. When vehicle is in motion inductive
sensors send signals to ECU. Front exciter ring is
fitted to outside diameter of constant velocity joint
inside each front hub assembly. The rear exciter ring
is bolted to the rear of each brake disc bell.7. Diagnostic plug connection
A diagnostic plug is located behind the dash. To the
left of the steering column on LHD vehicles. To the
right of the steering column on RHD vehicles. It is a 5
way blue connector.
The location and identification of ABS electrical relays
are given in the Electrical Troubleshooting Manual.
For location and identification of ABS electrical fuses.
See ELECTRICAL, Repair, Fuse Box - Interioror.
See ELECTRICAL, Repair, Fuse Box - Engine
Compartment
ANTI-LOCK BRAKE SYSTEM - ABS
Manufactured by WABCO
Introduction
The purpose of ABS is to prevent vehicle wheels
locking during brake application, thus maintaining
vehicle steerability and stability. This allows vehicle to
be steered whilst brakes are applied, even under
emergency conditions, and to avoid obstacles where
there is sufficient space to redirect the vehicle.
WARNING: ABS is an aid to retaining
steering control and stability while
braking.
·ABS cannot defy the natural laws of physics
acting on the vehicle.
·ABS will not prevent accidents resulting from
excessive cornering speeds, following
another vehicle too closely or aquaplaning,
i.e. where a layer of water prevents adequate
contact between tyre and road surface.
·The 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.
·The fitting of ABS does not imply that the
vehicle will always stop in a shorter stopping
distance.

70BRAKES
4
REPAIR MASTER CYLINDER NON ABS
Service repair no - 70.30.08 - Remove
Service repair no - 70.30.09 - Repair
- Lucas Girling - Type 25.4mm AS/AS
WARNING: This master cylinder is not
suitable to be fitted on vehicles with
antilock brake systems.
Before starting repair refer to general brake service
practice.
See General Brake Service Practice
Remove
1.Disconnect battery negative lead.
2.Place a suitable container under master cylinder
to catch brake fluid from cylinder when brake
pipes are disconnected.
3.Thoroughly clean immediate area around all
outlet ports. Remove each brake pipe, sealing
each pipe and outlet port with suitable plugs to
prevent ingress of foreign matter.
4.Disconnect electrical plug from low fluid switch
on reservoir cap.
5.Remove two nuts securing master cylinder to
servo unit remove also spring and plain washers.
6.Detach master cylinder from servo, remove
reservoir cap and drain brake fluid into a suitable
container.Repair
7.Thoroughly clean master cylinder and inspect
outer surfaces for damage and condition, renew
complete assembly if necessary.
8.Using two soft jaws, clamp master cylinder
flange in a suitable vice. Remove water ingress
'O' ring seal from master cylinder to servo flange
and discard.
9.Grip outside of transfer housing with a suitable
pair of pliers, carefully pull, working pliers in a
backwards and forwards rocking motion to ease
housing off master cylinder. Discard housing and
vacuum seal.

SUPPLEMENTARY RESTRAINT SYSTEM
7
REPAIR ROTARY COUPLER CENTRALISE
Fitting a rotary coupler which has not been centralised
could result in tape breakage. If the tape is broken, a
new rotary coupler must be fitted.
Providing the removal procedure has been correctly
followed this operation should not be necessary. If
however there is evidence of tampering, it is
imperative that the coupler is centralised.
CAUTION: Ensure wheels are positioned
straight ahead before fitting the rotary
coupler.
1.Correctly fit rotary coupler to column switch
assembly but do not fit steering wheel or make
any electrical connections.
See rotary coupler.
2.Depress rotary coupler locking peg and without
using undue force, rotate coupler anti-clockwise
as far as inner tape will allow. Releasing peg will
lock coupler in its current position.
NOTE: Do not apply excessive force when
limit is reached as this may result in tape
breakage. If no limit can be found, tape
has already broken and rotary coupler must be
replaced.
3.Having turned rotary coupler fully anti-clockwise
to limit position, proceed to turn coupler 2.5 turns
clockwise to obtain central position. (Coupler will
normally rotate a full five turns from
anti-clockwise limit to clockwise limit).
4.Make necessary electrical connections and refit
steering wheel.
See steering wheel.
5.Refit driver's airbag module.See driver's
airbag module.
COLUMN SWITCH ASSEMBLY
Service repair no - Indicator/lighting - 86.65.55
Service repair no - Wash/wipe - 84.15.34
Remove
1.Remove steering wheel.
See steering wheel.
2.Release 2 turnbuckles and remove lower dash
panel.

HEATING AND VENTILATION
3
REPAIR Air direction
3.Set control fully clockwise
4.Release outer cable from 2 clips on unit.
5.Release cable from stud on flap lever.
6.Remove control cable from control lever.
Temperature
7.Set RH control fully clockwise, LH control fully
anti-clockwise
8.Release outer cable from 2 clips on unit.
9.Release cable from stud on flap lever.
10.Remove control cable from control lever.
Refit
11.Reverse removal procedure. Check the
satisfactory function of the controls before fitting
louvre vent panel.RESISTOR UNIT
Service repair no - 80.20.17
Remove
1.Open glove box, manoeuvre side springs
through cut-outs and lower lid.
2.Remove 2 screws securing resistor unit to
trunking.
3.Disconnect multiplug and remove resistor unit.
Refit
4.Reverse removal procedure.

86ELECTRICAL
2
DESCRIPTION AND OPERATION ANTI-THEFT SYSTEM FUNCTION
Perimetric protection
Using the key in the correct sequence will turn on and
off perimetric protection only. When fully perimetrically
armed, all doors, and bonnet [hood] are protected
against unauthorised access. If the door key is used in
the normal manner the driver will be unaware of the
door key sequence. The time taken to lock or unlock
with the key must be less than 5 seconds. To prevent
unauthorised tampering, the alarm will sound if the
key is held in the unlocked position for longer than 5
seconds when armed. Cranking is disabled when
perimetric protection is armed.
NOTE: When key is turned left or right the
keyswitch input will be activated, in
conjunction with the sill button switch
when links are operated.
Volumetric protection
Using the handset transmitter will turn on and off
volumetric protection. In volumetric mode the vehicle
interior is protected using the ultrasonic sensor. Using
the handset also arms and disarms the vehicle
perimetrically. Cranking is disabled when volumetric
and perimetric protection is armed.
NOTE: If armed volumetrically the vehicle
CANNOT be disarmed using the key.
Alarm horn
When an intrusion is detected the alarm horn will
sound intermittently (Switzerland and Denmark
continuous horn sound) and the hazard lights flash
(where territorial regulations allow) for 30 seconds.
The alarm must be retriggered before alarm horn will
sound again.Vehicle status indication
Vehicle status is indicated by up to three devices: (a)
alarm horn, (b) hazard lights, (c) dash board LED.
When the vehicle arms in either mode the hazard
lights will flash three times and the LED will flash
rapidly for 10 seconds. LED will then flash at a slower
rate while vehicle is armed. When the vehicle disarms,
hazard lights will flash once and LED will extinguish. If
LED remains lit, it indicates that the alarm has been
triggered. Turning on ignition or arming the alarm will
extinguish LED. The LED will give a long pulse flash
to indicate the ultrasonic unit being activated.
Central locking
Central locking is controlled by the alarm ECU and
may be operated by the key, sill button(s) or handset.
The system works on both front doors on four door
vehicles or driver's door on two door vehicles.
NOTE: The central door locking system
will shut down for a short period after
more than 15 consecutive operations.
Inertia switch
An inertia switch is incorporated in the alarm system
ECU. If ignition is on and the vehicle receives an
impact sufficient to activate the inertia switch, the ECU
will signal to unlock central locking actuators and flash
hazard lights. Central locking will remain disabled for
30 seconds. To reset turn ignition off and then on after
the 30 second period has elapsed.
Ultrasonic unit
The unit operates by emitting an air pressure carrier
wave and receiving the wave back. Any disturbance
within the vehicle which disturbs the wave will be
detected, triggering the alarm.
When the volumetric sensor is activated it monitors
movement within the vehicle for 15 seconds before
detecting and responding to intrusions. If the sensor
detects movement within the vehicle it delays arming
until a 15 seconds quiet period has elapsed. If
continuous movement is detected the alarm will not
arm volumetrically.

ELECTRICAL
5
DESCRIPTION AND OPERATION ANTI THEFT ALARM SYSTEM
The main function of the system is to offer easy to use
remote locking and unlocking of the vehicle without
having to actively select the alarm function.
ALARM COMPONENTS
COMPONENT LOCATION
1. Electronic control unit (ECU) and relays Passenger footwell.................
2. Bonnet switch RH engine bay..........................................................
3. Door switches
4. Alarm sounder RH engine bay.........................................................
5. Light emitting diode (LED) Dash panel.......................................
6. Ultrasonic unit Roof map pocket.........................................................
7. Lock barrel, sill buttons
8. Handset transmitter
9. Aerial 'A' post, passenger side........................................................................

86ELECTRICAL
6
DESCRIPTION AND OPERATION ALARM COMPONENT LOCATIONS (96 MODELS)
COMPONENT LOCATION
1. Electronic control unit (ECU) and relays Under dash (passenger side).................
2. Anti-theft alarm indicator light Instrument panel..................................
3. Engine immobilisation warning light (EIWL) * Instrument panel..........
4. Passive coil Over starter switch barrel.............................................................
5. Bonnet switch RH engine compartment..........................................................
6. Door switches
7. Ultrasonic sensor Interior light switch panel....................................................
8. Lock barrel, sill buttons
9. Handset and key
10. Battery backed-up sounder or horn * RH engine compartment......................
11. Immobilisation unit (spider) * Above heater...................................
12. Aerial Part of fascia harness.......................................................................
* where applicable

ELECTRICAL
7
DESCRIPTION AND OPERATION ANTI-THEFT ALARM DESCRIPTION (96 MODELS)
NOTE: The alarm system provides security
protection under wide ranging
circumstances and is fully programmable
to meet market requirements; consequently some
of the features listed will vary dependent on
vehicle model or territory.
The handset is intended to be the primary source of
control for the alarm system. The key should only be
used in the event of handset failure or if perimetric
arming only is required.
Immobilisation
After a time period the vehicle is automatically
immobilised regardless of whether or not the alarm is
armed.
Mobilisation
The handset provides the normal means of
mobilisation. In the event of handset failure, the key
may be used to enter the emergency key access
code.
Perimetric arming
Provides protection whilst the vehicle is still occupied.
Volumetric arming
If movement within the vehicle is detected the alarm
will be triggered.
NOTE: Perimetric arming always
accompanies volumetric arming.
Built-in test
The alarm system has a built-in test procedure, but if
possible any fault finding should normally be
undertaken using TestBook.
Emergency key access (EKA)
In the event of handset failure the alarm can be
disarmed by entry of the EKA code which is unique to
each vehicle.CONTROL SYSTEM
Electronic control unit (ECU) and relays
The ECU is the alarm system 'brain' and controls all
alarm functions. It responds to inputs received, by
supplying suitable outputs to indicate the status of the
alarm system or activating the relevant warning
devices.
Handset
The handset is the primary source of control for the
alarm system i.e. it locks and unlocks the vehicle,
arms and disarms the alarm.
Door key
The vehicle may be locked using the key (perimetric
arming only).
NOTE: The vehicle MUST be unlocked
using the handset. The key may be used to
unlock the vehicle if the handset fails to
operate, see operation, Emergency key access.
Passive coil
The passive coil is located around the starter switch
and triggers the handset (usually located on the
keyring) if it is within close proximity.
Aerial
The aerial is a floating connection which supplies the
alarm ECU with the signal received from the handset.
Immobilisation unit (spider)
Dependent on model or territory, the system may be
fitted with an immobilisation unit which is discreetly
located and provides an interface between the ECU
and immobilised areas of the vehicle.