LAND ROVER DISCOVERY 1999 Workshop Manual

BRAKES
70-48 REPAIRS
Sensor – ABS – front
$% 70.65.30
ABS sensor is supplied fitted to wheel hub and
must not be removed.
Remove
1.Remove wheel hub.

+ FRONT SUSPENSION, REPAIRS,
Wheel hub.
Refit
1.Fit wheel hub.

+ FRONT SUSPENSION, REPAIRS,
Wheel hub.
Sensor – ABS – rear
$% 70.65.31
ABS sensor is supplied fitted to wheel hub and
must not be removed.
Remove
1.Remove wheel hub.

+ REAR SUSPENSION, REPAIRS,
Wheel hub.
Refit
1.Fit wheel hub.

+ REAR SUSPENSION, REPAIRS,
Wheel hub.

BRAKES
REPAIRS 70-49
Modulator unit - ABS
$% 70.65.49
Remove
1.Position cloth under modulator to absorb fluid
spillage.
CAUTION: Brake fluid will damage paint
finished surfaces. If spilled, immediately
remove fluid and clean area with water.
2.Disconnect 3 multiplugs from ABS modulator.
3.Disconnect 2 inlet brake pipe unions from pump
side of modulator.
CAUTION: Always fit plugs to open
connections to prevent contamination.
4.Disconnect 4 outlet brake pipe unions from top
of modulator.
CAUTION: Always fit plugs to open
connections to prevent contamination.
5.Loosen 3 nuts securing modulator to mounting
bracket.
6.Release and remove modulator from mounting
bracket.
7.Remove 3 mounting rubbers from modulator. Refit
1.Position mounting rubbers to modulator.
2.Position modulator to mounting bracket,
tighten nuts to 9 Nm (7 lbf.ft).
3.Clean brake pipe unions.
4.Connect brake pipe unions to modulator
ensuring pipes are connected to their correct
ports.
5.Tighten 13 mm unions to 22 Nm (16 lbf.ft) and
11 mm unions to 14 Nm (10 lbf.ft).
6.Connect multiplugs to modulator.
7.Bleed brakes.

+ BRAKES, ADJUSTMENTS, Brake
system bleeding.
8.To ensure correct operation, the ABS system
MUST be tested using TestBook.

BRAKES
70-50 REPAIRS
Switch - Hill descent control
$% 70.70.11
Remove
1.Carefully remove switch.
2.Disconnect multiplug from switch.
3.Remove switch.
Refit
1.Connect multiplug switch.
2.Position switch and push to secure.
Switch - handbrake
$% 86.65.45
Remove
1.Remove centre console.

+ INTERIOR TRIM COMPONENTS,
REPAIRS, Console - centre - automatic
models.

+ INTERIOR TRIM COMPONENTS,
REPAIRS, Console - centre - manual
models.
2.Disconnect Lucar from handbrake warning
switch.
3.Remove clip and clevis pin securing cable to
handbrake lever.
4.Remove 2 bolts and remove handbrake lever.
5.Remove 2 screws securing switch to
handbrake lever and remove switch.
Refit
1.Fit switch to handbrake lever and tighten
screws.
2.Position handbrake lever to floor and tighten
bolts to 22 Nm (16 lbf.ft).
3.Align cable to handbrake lever and fit clevis pin
and clip.
4.Connect Lucar to handbrake switch.
5.Fit centre console.

+ INTERIOR TRIM COMPONENTS,
REPAIRS, Console - centre - automatic
models.

+ INTERIOR TRIM COMPONENTS,
REPAIRS, Console - centre - manual
models.

RESTRAINT SYSTEMS
DESCRIPTION AND OPERATION 75-1
RESTRAINT SYSTEMS DESCRIPTION AND OPERAT ION
SRS component layout
RHD shown, LHD similar
1DCU
2SRS warning lamp
3Driver airbag module4Driver seat belt pretensioner
5Passenger airbag module
6Passenger seat belt pretensioner

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

RESTRAINT SYSTEMS
DESCRIPTION AND OPERATION 75-3
Description - SRS
General
The purpose of the Supplementary Restraint System (SRS) is to reduce the impact of the driver and passenger
against the vehicle's interior in the event of a serious accident.
The SRS system is a stand-alone system. There are no remotely mounted crash sensors. The only external input to
the DCU is power. The system only becomes live when the ignition is switched on.
The SRS consists of the following components:
lDiagnostic and control unit (DCU).
lSRS warning lamp.
lRotary coupler.
lDriver airbag module.
lDriver seat belt pretensioner.
lPassenger airbag module.
lPassenger seat belt pretensioner.
The passenger airbag is optional in some markets. All other components are standard fit in all markets. The SRS
functions the same in all markets.

RESTRAINT SYSTEMS
75-4 DESCRIPTION AND OPERATION
Driver airbag module
The driver airbag module is located in the steering wheel and is controlled by the DCU. A bag within the module
inflates to protect the driver in the event of a collision severe enough to deploy the system.
The driver airbag module connects to the steering column wiring harness via a rotary coupler.
Within the driver airbag module is a squib which, when given the correct current by the DCU, inflates the airbag by
initiating a chemical reaction. In deployment, the airbag inflates within a fraction of a second and then deflates at a
controlled rate as the weight of the driver presses against the bag. Vents in the bag control airbag deflation.
The DCU regularly applies a test current to the driver airbag squib to confirm continuity of the ignition circuitry.
The DCU is capable of detecting a short to ground, a short to battery and an open circuit for the driver airbag module
squib. It will also identify if the configuration of the DCU differs from that actually fitted to the vehicle.
The DCU also stores the following additional information on each fault:
lA count indicating the number of times the fault has occurred.
lA start time and an end time for the fault to indicate duration of the fault.

RESTRAINT SYSTEMS
DESCRIPTION AND OPERATION 75-5
Passenger airbag module
The passenger airbag module is located in the instrument panel above the glove box and is controlled by the DCU.
A bag within the module inflates to protect the passenger in the event of a collision severe enough to deploy the
system.
Within the passenger airbag module is a squib which, when given the correct current by the DCU, inflates the airbag
by initiating a chemical reaction. In deployment, the airbag inflates within a fraction of a second and then deflates at
a controlled rate as the weight of the passenger presses against the bag. Vents in the bag control airbag deflation.
The DCU regularly applies a test current to the passenger airbag squib to confirm continuity of the ignition circuitry.
The DCU is capable of detecting a short to ground, a short to battery and an open circuit for the passenger airbag
module squib. It will also identify if the configuration of the DCU differs from that actually fitted to the vehicle.
The DCU also stores the following additional information on each fault:
lA count indicating the number of times the fault has occurred.
lA start time and an end time for the fault to indicate duration of the fault.

RESTRAINT SYSTEMS
75-6 DESCRIPTION AND OPERATION
Seat belt pretensioners
The seat belt pretensioners are located within the front seat belt anchors and are controlled by the DCU. They are
pyrotechnic devices that, when deployed, tighten the front seat belts. This works in conjunction with the airbag
module(s) to protect front seat occupants in the event of an accident.
The DCU regularly applies a test current to the seat belt pretensioner squibs to confirm continuity of the ignition
circuitry.
The DCU is capable of detecting a short to ground, a short to battery and an open circuit for the squibs. It will also
identify if the configuration of the DCU differs from that actually fitted to the vehicle.
The DCU also stores the following additional information on each fault:
lA count indicating the number of times the fault has occurred.
lA start time and an end time for the fault to indicate duration of the fault.

RESTRAINT SYSTEMS
DESCRIPTION AND OPERATION 75-7
SRS warning lamp
The SRS warning lamp located in the instrument cluster indicates the following:
lThe status of the system readiness check on start-up.
lA fault within the SRS system.
The input to the SRS warning lamp from the DCU is 12 volts during the readiness test, 0 volts if no fault present and
12 volts if a fault is detected.
The DCU is capable of detecting an open circuit or a short circuit for the SRS warning lamp.
The DCU also stores the following additional information on each fault:
lA count indicating the number of times the fault occurred.
lA start and end time for the fault to indicate the duration of the fault.