belt LAND ROVER DISCOVERY 2002 Repair Manual

BRAKES
70-10 DESCRIPTION AND OPERATION
Vacuum pump (diesel models only)
1Alternator
2Vacuum pump
3Brake servo assembly vacuum connection
4Oil feed pipe
5Oil drain pipe
As the diesel engine air inlet system does not produce sufficient depression to operate the brake servo assembly, an
engine driven vacuum pump is installed.
The vacuum pump is integrated with the engine alternator and driven by the auxiliary drive belt. The pump is a rotary
vane type, lubricated and cooled by engine oil supplied through a pipe connected to the engine block and returned
through a pipe connected to the engine oil sump. Air extracted from the brake servo assembly is vented into the oil
sump with returning lubricating oil.

BRAKES
70-42 REPAIRS
Vacuum pump - servo
$% 70.50.19
Remove
1.Remove auxiliary drive belt.

+ CHARGING AND STARTING,
REPAIRS, Belt - auxiliary drive.
2.Release cover and remove nut securing lead
to alternator.
3.Disconnect alternator multiplug.
4.Remove bolt (LH thread) and remove auxiliary
drive belt tensioner. 5.Remove bolt securing support stay to
alternator.
6.Release clip and disconnect oil drain hose from
vacuum pump.
7.Disconnect vacuum pump oil supply pipe from
cylinder head and discard 'O' ring.
8.Remove bolt securing alternator and release
from mounting bracket.
9.Disconnect vacuum hose from vacuum pump.
10.Remove alternator. Take care not to damage
radiator cooling fins.
11.Remove 4 bolts, and remove vacuum pump
from alternator.
CAUTION: Always fit plugs to open
connections to prevent contamination.

BRAKES
REPAIRS 70-43
Refit
1.Clean mating faces of alternator and vacuum
pump.
2.Fit vacuum pump to alternator and tighten
bolts to 8 Nm (6 lbf.ft).
3.Position alternator to engine and connect
multiplug.
4.Connect vacuum hose and oil drain hose to
vacuum pump and secure clips.
5.With assistance align alternator to mounting
bracket and fit but do not tighten bolt.
6.Fit bolt securing support stay to alternator and
tighten to 25 Nm (18 lbf.ft) .
7.Tighten bolt securing alternator to mounting
bracket to 45 Nm (33 lbf.ft).
8.Using new 'O' ring, connect oil supply pipe to
cylinder head and tighten to 10 Nm (7 lbf.ft).
9.Connect lead to alternator and tighten nut to 6
Nm (4.4 lbf.ft).
10.Fit auxiliary drive belt tensioner and tighten bolt
to 50 Nm (37 lbf.ft).
11.Fit auxiliary drive belt.

+ CHARGING AND STARTING,
REPAIRS, Belt - auxiliary drive.
Housing - caliper - front
$% 70.55.24
Remove
1.Raise front of vehicle, one side.
WARNING: Do not work on or under a
vehicle supported only by a jack. Always
support the vehicle on safety stands.
2.Remove road wheel(s).
3.Clamp brake hose to prevent fluid loss.
4.Remove brake hose banjo bolt and discard
sealing washers.
CAUTION: Always fit plugs to open
connections to prevent contamination.
5.Remove 2 guide pin bolts and remove caliper
housing from carrier.
6.Remove 2 brake pads from caliper carrier.

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 module
4Driver 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 module
4Driver 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
75-6 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
75-8 DESCRIPTION AND OPERATION
Diagnostic and Control Unit (DCU)
The SRS DCU is an electronic single point crash sensor. It is capable of sensing if a crash has taken place. If all the
relevant parameters are met, then the DCU deploys the airbag(s) and seat belt pretensioners.
The DCU is bolted to the transmission tunnel beneath the centre console in the area of the handbrake.
The DCU performs the following functions:
lInternal self test, system monitoring and fault detection.
lSRS warning lamp operation.
lSystem deployment.
Self test, system monitoring and fault detection
The DCU performs a self-test during start-up and then continually during operation of the system. The following
components are tested:
lThe decelerometer.
lThe electromechanical safing sensor.
lThe microprocessor.
lThe continuity of squib ignition circuits.
lThe SRS warning lamp.
If the DCU detects a fault, it stores the fault code in memory. Diagnose the DCU with TestBook. The DCU cannot
be serviced. It must be replaced if it is faulty.
SRS warning lamp operation
The DCU controls the SRS warning lamp contained in the instrument cluster.
System deployment
The DCU determines when the system deploys based on inputs from both the decelerometer and the
electromechanical safing sensor. Both are located within the DCU. Neither are serviceable.
The electromechanical safing sensor uses a magnet and ball bearing system to provide a mechanical confirmation of
vehicle deceleration. The ball bearing is held in place by the magnet. The strength of the magnet is calibrated such
that the force required for the ball bearing to move away from the magnet will only occur if the vehicle decelerates
suddenly, as in an accident.
The SRS deploys only if both the decelerometer reading and the safing sensor operation occur at the same time.

RESTRAINT SYSTEMS
DESCRIPTION AND OPERATION 75-9
Operation - SRS
The diagnostic and control unit (DCU) controls the SRS system. The DCU is located beneath the centre console close
to the handbrake area. The DCU contains both an electronic deceleration sensor as well as an electromechanical
safing sensor. When the electronic deceleration sensor within the DCU detects rapid deceleration of the vehicle, it
compares the deceleration rate with stored values in its' memory. If the deceleration rate exceeds the stored value
and the electromechanical safing sensor triggers, the DCU deploys the airbag and the seat belt pretensioners. The
DCU will not deploy the airbags and seat belt pretensioners unless both sensors trigger.
The SRS has diagnostic capabilities through TestBook. In the event that a fault is detected, the DCU alerts the driver
by illuminating a warning lamp in the instrument cluster.
The DCU controls the following:
lSRS warning lamp.
lDrivers airbag module.
lPassenger airbag module (where fitted).
lDriver seat belt pretensioner.
lPassenger seat belt pretensioner.
WARNING: The integrity of the SRS system are critical for safety reasons. Ensure the following precautions
are always adhered to:
lNever install used SRS components from another vehicle or attempt to repair an SRS component.
lWhen repairing an SRS system only use genuine new parts.
lNever apply electrical power to an SRS component unless instructed to do so as part of an approved test
procedure.
lSpecial Torx bolts are necessary for installing the airbag module - do not use other bolts. Ensure bolts
are tightened to the correct torque.
lAlways use new fixings when replacing an SRS component.
lEnsure the SRS Diagnostic Control Unit (DCU) is always installed correctly. There must not be any gap
between the DCU and the bracket to which it is mounted. An incorrectly mounted DCU could cause the
system to malfunction.
System deployment
The airbag and seat belt pretensioners deploy to protect the front seat occupants when the DCU senses a rapid
vehicle deceleration. The system deploys when the following conditions are met:
lThe ignition switch is on.
lThe vehicle decelerates beyond a threshold defined within the DCU.
lThe electromechanical safing sensor within the DCU triggers.
When all of the above conditions are met, the DCU deploys the airbag(s) and seat belt pretensioners. If the above
conditions are not met, the DCU will not deploy the system.
Component replacement policy
After an impact which deploys the airbags and pretensioners, the following components must be renewed:
lDCU.
lDriver and passenger airbag modules.
lDriver and passenger buckle pretensioners.
lRotary coupler.
lFlyleads (where applicable) connecting airbags and pre-tensioners to SRS harness

RESTRAINT SYSTEMS
DESCRIPTION AND OPERATION 75-11
DESCRIPTION AND OPERAT ION
Description - seat belts
An inertia reel, three point seat belt is installed at each seat position. The inertia reels incorporate a liftshaft locking
system with webbing sensor and car sensor activating mechanisms. The webbing sensor activates the locking system
if the webbing is subjected to a sharp pull. The car sensor activates the locking system if the vehicle is subjected to
sudden deceleration or a severe tilt angle.
Front seat belts
The inertia reel of each front seat belt is attached to the related B/C post, behind the finishers. The webbing runs from
the inertia reel, through a height adjuster, to an anchor point at the base of the B/C post. The buckle assembly for
each belt is attached to the inboard side of the seat and contains the SRS pretensioner.
Rear seat belts
The inertia reels for the outboard rear seats are attached to the body behind the loadspace side trim casings. The
webbing runs from each inertia reel through an upper mounting, suspended from the cantrail, to an anchor point on
the rear wheel arch.
The inertia reel of the centre rear seat is mounted in the back of the seat. The webbing runs through a guide on the
top of the seat and is anchored to one of the seat hinge points. The buckles for the rear seat belts are also attached
to the seat hinge points.
Third row seat belts
The inertia reel of each third row rear seat belt is attached to the related E post, behind the loadspace side trim
casing.The webbing runs from the inertia reel, through an upper mounting on the E post to an anchor point on the
loadspace floor. The buckle is mounted on the inboard side of the seat.