lock LAND ROVER DISCOVERY 2002 Workshop Manual

REAR SUSPENSION
64-8 DESCRIPTION AND OPERATION
The pivot housing is located in a fabricated bracket centrally located on the rear of the axle. The central bush of the
pivot housing is secured in the bracket with a bolt and locknut. Fabricated brackets on each chassis longitudinal
provide for the attachment of each transverse link. Each link is secured through its bush with a bolt and locknut. The
forked end of each link locates over the bushes at each end of the pivot housing and is secured with a bolt and locknut.
The attachment bolts for each link are coated with a clear, dry wax which reduces friction on the bolt and allows the
correct torque to be applied to the clamping of the bushes. The bolts can be re-used, but if bolt replacement is
necessary the correct bolt with the wax coating must be used.
Anti-roll bar
The anti-roll bars fitted differ between ACE and non-ACE vehicles. On non-ACE vehicles a conventional 'passive' anti-
roll bar is used. On ACE vehicles an 'active' torsion bar is used. Both types are attached to the tubular cross-member
at the rear of the chassis with mounting rubbers and clamp plates. The clamp plates locate in fabricated brackets
attached to the tubular cross-member and secured with bolts.
Each end of the anti-roll bar is attached to an anti-roll bar link. Each link has a spherical bearing attached at each end.
One end is attached to a bracket on the axle and secured with a locknut. The opposite end attaches through a hole
in the anti-roll bar and is also secured with a locknut. On 'active' torsion bars, the RH anti-roll bar link is attached to a
long arm which in turn is attached to the anti-roll bar.
Passive anti-roll bar
The passive anti-roll bar is a conventional anti-roll bar which opposes axle movement, reducing the effects of lateral
forces on the vehicle body.
With the conventional passive anti-roll bar, axle movement is opposed by the anti-roll bar through links attached to
the axle casing and each end of the anti-roll bar.
On vehicles with coil springs (no SLS fitted) the anti-roll bar is manufactured from 19 mm (0.74 in.) diameter spring
steel bar.
On vehicles with air springs (SLS fitted) the anti-roll bar is manufactured from 29 mm (1.14 in.) diameter spring steel
bar.
Active torsion bar

+ FRONT SUSPENSION, DESCRIPTION AND OPERATION, Description - ACE.The 'active' torsion bar is
used in conjunction with the ACE system to control body roll and directional stability giving a reduction of the effects
of lateral forces on the vehicle body over a conventional 'passive' anti-roll bar.
The torsion bar opposes axle movement by the application of a hydraulic force to oppose the lateral forces through
links attached to the axle casing and each end of the bar. The torsion bar is made from 35 mm (1.4 in.) diameter spring
steel. One end is fitted with an arm which is operated by a hydraulic actuator to oppose corning forces.

REAR SUSPENSION
64-12 DESCRIPTION AND OPERATION
Description - SLS
General
The Self Levelling Suspension (SLS) system is an optional fitment and comprises an Electronic Control Unit (ECU),
air supply unit, two air springs and two height sensors. The SLS system only operates on the rear suspension and is
designed to keep the vehicle level to compensate for uneven loads or when towing. The system controls the gap
between the chassis and the rear axle to a tolerance of
± 0.5 mm (0.02 in). The ride height of the rear of the vehicle
can be controlled in three modes of operation; normal ride height, Off-Road Mode (ORM) and extended mode. A
transportation mode, initiated using TestBook, is also available for moving the vehicle on a trailer.
The system is controlled electronically by an ECU which is shared with the ABS system and known as the Self
Levelling and Anti-Lock Braking System (SLABS) ECU. The system operates by using an air supply unit to inflate or
deflate the air springs to maintain a constant ride height.
An accessory remote handset is available to remotely operate the SLS system to allow easier connection and
disconnection of trailers.
Two SLS system warning lamps are located in the instrument pack. The warning lamp in the bottom left corner of the
instrument pack is the SLS warning lamp. If a fault is detected in the system, the warning lamp will illuminate
continuously in an amber colour. The warning lamp also flashes in an amber colour when the remote handset is being
used. The second warning lamp, located in the top right of the instrument pack is the ORM warning lamp. When ORM
is selected the warning lamp is continuously illuminated in an amber colour. When the SLS is between standard ride
height and ORM or in extended mode, the warning lamp will flash. Standard ride height, measured between the tip of
the axle bump stop rubber and the axle, is 61.5 mm (2.42 in). ORM ride height, measured between the tip of axle
bump stop and the axle, is 100 mm (3.93 in).
A switch is located in the group of six switches on the fascia and is used to select the ORM. The switch is non-latching
and must be depressed for a minimum of 0.5 seconds to signal the ECU that ORM has been requested.

REAR SUSPENSION
DESCRIPTION AND OPERATION 64-15
Height sensors
1Spacer
2Link end
3Link
4Link end
5Arm
6Sensor body
Two height sensors are located on the outside of each chassis longitudinal forward of the rear axle. Each sensor body
is attached to a fabricated bracket and secured with two screws. The sensor is attached to the top of each radius arm
by an arm, a link and two link ends. The link ends allow articulation of the arm to allow for suspension travel. The lower
link arm is attached to a lug of the top of the radius arm and is secured with a bolt and locknut.
The sensor body and arm are manufactured from moulded nylon. The two link ends are made from natural rubber
and the link is made from mild steel. The rubber link ends allow flexibility of the arm and resistance to damage.
Each sensor is connected to the main chassis harness by a multiplug. The three pin multiplug provides an earth, a 5
V supply voltage and an output signal voltage to the SLABS ECU.
Each sensor operates on the Hall effect principle. A magnet is attached to the shaft and rotates with movement of the
arm. The magnetic flux generated acts on a Hall effect sensor and depending on its position varies the current across
the sensor. This current is measured and amplified and passed to the SLABS ECU as a linear output voltage signal,
which varies depending on the angular position of the sensor. The signal information is processed and the ECU can
determine the vehicle height.
When the sensors are replaced or removed for any reason, a calibration procedure is required to recalibrate the
sensors and the SLABS ECU. The calibration procedure requires the use of TestBook and calibration blocks to set
the axle to chassis height to a known value.
If faults occur with the height sensors, fault codes are stored in the SLABS ECU. The current and past fault codes can
be retrieved with TestBook.

REAR SUSPENSION
64-18 DESCRIPTION AND OPERATION
The ECU supplies a 5 V current to each of the height sensors. Each height sensor uses the current to supply an
analogue input to the ECU. The ECU can calculate from the input received from each height sensor the height of the
vehicle and can then power the air supply unit as necessary to raise or lower one or both air springs to level the
vehicle.
When SLS compressor operation is required, the ECU provides a battery supply to energise the SLS relay located in
the engine compartment fusebox. When the relay contacts close, a 12 V supply passes through fusible link 9 in the
engine compartment fusebox, through the relay contacts and operates the air supply unit compressor. The ECU will
then supply power to operate one or both air control valve solenoids and/or the exhaust valve solenoid to inflate or
deflate the air springs as required. The compressor does not need to be powered to deflate the air springs.
The ECU also controls the operation of the SLS audible warning, the SLS warning lamp and the ORM warning lamp.
When the ignition is switched to position II, the ECU performs a three second bulb check and illuminates the SLS and
ORM warning lamps in the instrument pack to check for operation. When the system is operating or a fault is sensed
by the ECU, the ECU will operate the appropriate warning lamp and audible warning as required. The audible warning
is operated by the Body Control Unit (BCU) when it receives a signal from the SLABS ECU. The audible warning is
emitted from a speaker at the rear of the instrument pack.
Depressing the ORM switch for a minimum of 0.5 seconds, completes an earth which the ECU uses as a signal to
initiate the ORM if conditions allow. When the ECU starts ORM, the same earth that was completed by the ORM
switch is pulled to earth by the ECU to activate the ORM warning lamp. The ECU checks for a further operation of the
ORM switch by continuously and very quickly removing the earth for the ORM warning lamp. If the ORM switch is
operated for more than 0.5 seconds, the ECU will detect this and de-activate the ORM.
The SLS part of the SLABS ECU also uses the road speed data generated within the SLABS ECU by the ABS system.
Operation of ORM and extended mode are road speed sensitive and use the ABS signal to monitor the vehicle speed.
When the accessory remote handset is used for the SLS lower and raise functions, the handset transmits RF signals
which are received by the same RF receiver used for the alarm/remote door locking system. The RF receiver passes
this data as a 25 Hz PWM signal to the BCU. The BCU then transmits this data to the SLABS ECU as raise or lower
data. TestBook is required to program the BCU for remote handset operation.
SLABS ECU connector pin details
Connector/Pin No. Description Input/Output
C0504
1 Battery supply Input
2 Ignition supply Input
5 K line (diagnostics) Input/Output
12 EarthInput
C0654
1 Left height sensor supply Output
2 Left height sensor earth Input
3 Left height sensor signal Input
4 Right height sensor supply Output

REAR SUSPENSION
DESCRIPTION AND OPERATION 64-21
Normal ride height
When the vehicle is stationary, a door is open and the ignition is off, the SLS system will allow the rear of the vehicle
to lower to within 20 mm of the normal ride height as load is removed from the vehicle. The SLS system will only
operate the compressor to raise the rear of the vehicle when the engine is running, unless requested using the remote
handset.
Off-road mode (ORM)
ORM is used to raise the rear of the vehicle from normal ride height to the ORM ride height of 100 mm between the
tip of the bump stop and the axle.
ORM is activated by depressing the ORM switch located on the fascia for not less than 0.5 seconds. With the engine
running, all doors closed and the vehicle speed below 18 mph (30 km/h), the audible warning will sound once and the
ORM warning lamp in the instrument pack will start to flash when the switch is released. The compressor will be
started and the air control valves will be energised by the ECU to inflate the air springs and raise the rear of the vehicle.
When the full ORM height is reached, the ECU will terminate compressor operation and close the air valves. The ORM
warning lamp will stop flashing and remain continuously illuminated to inform the driver that the SLS system is in ORM.
When ORM is no longer required, depressing the ORM switch for not less than 0.5 seconds with all doors closed will
lower the SLS to normal ride height. The audible warning will sound once and the ORM warning lamp will flash as the
suspension lowers. The ECU energises the air control valves and the exhaust valve to release air pressure from the
air springs. When standard ride height is reached the ORM warning lamp will extinguish and the ECU will de-energise
the air control valves and the exhaust valve solenoids.
If the SLS is in ORM and the vehicle speed exceeds 18 mph (30 km/h), the ECU will lower the SLS to standard ride
height. The driver will be informed of this by an audible warning and the ORM warning lamp flashing as the suspension
lowers. When normal ride height is achieved, the ORM warning lamp will extinguish.
At sea level, the time to change the SLS from normal ride height to ORM or visa versa will take between 15 and 20
seconds.
If the ECU determines that conditions are not correct for SLS operation, i.e.; axle articulation or system fault, the
audible warning will sound three times to inform the driver that the ORM request has not been granted.
Extended mode
The extended mode is automatically operated by the ECU and requires no input from the driver. Extended mode
operates when the chassis is grounded causing the rear wheels to spin. This information is generated by the ABS
function of the SLABS ECU.
When the ECU senses that the chassis is grounded and the vehicle speed is less than 6 mph (10 km/h), the ECU will
operate the compressor and energise the air control valves for 25 seconds to raise the rear of the vehicle. This
operates irrespective of the mode that the SLS system is in at that time. To inform the driver, the ORM warning lamp
will flash continuously at all times that the system is in extended mode.
The driver can exit the extended mode by depressing the ORM switch for not less than 0.5 seconds or by exceeding
8 mph (13 km/h).
Remote handset SLS control
The remote handset is an accessory item which allows the SLS to be operated between normal ride height and bump
stop height to allow easier connection and disconnection of trailers. The remote handset is similar in appearance to
that of the remote door locking handset but does not have an integral key. A circular button with an arrow is used to
raise the SLS and an oval button with the 'Land Rover' logo is used to lower the SLS.
The remote handset control requires all doors to be closed and the ignition to be in position II, but the engine does
not need to be running.

REAR SUSPENSION
ADJUSTMENTS 64-23
ADJUST ME NTS
SLS calibration blocks
$% 64.50.38
Fit
1.Connect TestBook to vehicle.
2.Ensure contact faces of calibration blocks LRT-
64-003/1 and LRT-64-003/2 are clean.
3.Using Testbook, operate the SLS system to
raise the body, position the calibration blocks
LRT-64-003/1 and LRT-64-003/2 between the
rear axle and the body, then lower the body
onto the calibration blocks. The calibration
blocks are handed and only fit one way.
Remove
1.Using Testbook, operate the SLS system to
raise the body, remove the calibration blocks
LRT-64-003/1 and LRT-64-003/2 from
between the rear axle and the body.
2.Disconnect TestBook from the vehicle.

REAR SUSPENSION
64-28 REPAIRS
Air spring - SLS
$% 64.21.01
Remove
1.Using TestBook, depressurise SLS air system.
After depressurisation, approximately 1 bar
(15 lbf.in
2) air pressure remains in the
system.
2.Raise rear of vehicle and support under
chassis.
WARNING: Do not work on or under a
vehicle supported only by a jack. Always
support the vehicle on safety stands.
3.Remove road wheel.
4.Remove 2 clips securing air spring to chassis.
5.Collapse air spring and disconnect pipe from
top of air spring.
CAUTION: Always fit plugs to open
connections to prevent contamination.
6.Rotate air spring, to unlock from axle and
remove from vehicle.
7.Remove connector from pipe.Refit
1.Clean mating faces of air spring, axle and
chassis.
2.Fit pipe connector to air spring.
3.Locate air spring on axle and rotate 90
° to fully
engage bayonet fitting.
4.Connect pipe to top of air spring.
5.Engage top locating pins of air spring in chassis
and secure with clips.
6.Fit road wheel and tighten nuts to 140 Nm (103
lbf.ft).
7.Remove stand(s) and lower vehicle.

REAR SUSPENSION
64-32 REPAIRS
Sensor - height - SLS
$% 64.36.01
WARNING: Ensure the air suspension system is
made safe before commencing work. Otherwise
the chassis may lower onto the bump stops
during repair.
Remove
1.Raise rear of vehicle.
WARNING: Do not work on or under a
vehicle supported only by a jack. Always
support the vehicle on safety stands.
2.Disconnect height sensor multiplug.
3.Remove bolt securing height sensor link to
radius arm.
4.Remove 2 bolts securing height sensor to
chassis and remove height sensor.
Refit
1.Position height sensor to chassis and tighten
bolts to 6 Nm (4.4 lbf.ft).
2.Position height sensor link to radius arm and
tighten bolt to 25 Nm (18 lbf.ft).
3.Connect height sensor multiplug.
4.Remove stand(s) and lower vehicle.
5.Use TestBook to calibrate height sensor.
Compressor unit - air - SLS
$% 64.50.10
WARNING: Ensure the air suspension system is
made safe before commencing work. Otherwise
the chassis may lower onto the bump stops
during repair.
Remove
1.Using TestBook, depressurise SLS air system.
After depressurisation, approximately 1 bar
(15 lbf.in
2) air pressure remains in the
system.
2.Release 2 fasteners and remove air
compressor unit cover.
3.Remove 2 bolts securing air compressor unit to
chassis. Release unit and lower onto blocks to
support the weight.
4.Noting their fitted position, disconnect pipes
from air valves.
CAUTION: Always fit plugs to open
connections to prevent contamination.

REAR SUSPENSION
REPAIRS 64-33
5.Disconnect inlet and exhaust pipes.
CAUTION: Always fit plugs to open
connections to prevent contamination.
6.Disconnect multiplugs from air valves, exhaust
valve and compressor.
7.Release and disconnect compressor multiplug
from casing.
8.Remove air compressor unit from vehicle.
9.Release supply/exhaust pipe.
CAUTION: Always fit plugs to open
connections to prevent contamination.
10.Remove 3 bolts securing compressor to
casing. Remove compressor and collect
mounting washers. Refit
1.Locate mounting washers and position
compressor in casing.
2.Apply Loctite 270 to compressor securing bolts.
Fit bolts and tighten to 7 Nm (5.2 lbf.ft).
3.Connect compressor multiplug to casing.
4.Connect supply/exhaust pipe.
5.Position air compressor unit on support block,
connect inlet and exhaust pipes.
6.Connect multiplugs to air valves, exhaust valve
and compressor.
7.Connect pipes to air valves.
8.Position air compressor unit to chassis and
engage casing in retaining lugs. Fit air
compressor unit securing bolts and tighten to
25 Nm (18 lbf.ft).
9.Ensure pipes are located in cut outs in casing.
10.Position air compressor unit cover and lock
fasteners.

REAR SUSPENSION
REPAIRS 64-35
Air valve - SLS
$% 64.50.47
WARNING: Ensure the air suspension system is
made safe before commencing work. Otherwise
the chassis may lower onto the bump stops
during repair.
Remove
1.Using TestBook, depressurise SLS air system.
After depressurisation, approximately 1 bar
(15 lbf.in
2) air pressure remains in the
system.
2.Release 2 fasteners and remove air
compressor unit cover.
3.Noting their fitted position, disconnect pipes
from air valves and discard 'O' rings.
4.Disconnect air valve multiplugs.
5.Remove 2 bolts securing air valves and
remove air valves. Refit
1.Position air valves and fit and tighten bolts.
2.Connect air valve multiplugs.
3.Connect air valve pipes.
4.Ensure pipes are located in cut outs in casing.
5.Position air compressor unit cover and lock
fasteners.