ECU LAND ROVER DISCOVERY 1999 Workshop Manual

REAR SUSPENSION
64-22 DESCRIPTION AND OPERATION
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.
Pressing the lower button will signal the SLABS ECU, via the RF receiver and the BCU, to energise the exhaust valve
and air control valves. The SLS will lower up to 60 mm (2.36 in) below normal ride height if the button is held. If the
button is released the SLS will stop at that point.
Pressing the raise button will signal the SLABS ECU, via the RF receiver and the BCU, to start the compressor and
energise the exhaust valve and air control valves. The SLS will raise to normal ride height if the button is held. If the
button is released the SLS will stop at that point.
When raising or lowering the SLS using the remote handset, the SLS warning lamp will flash and the audible warning
will sound when the system is operating. When the SLS is fully lowered the warning lamp will stay illuminated. The
SLS will reset to normal ride height if the vehicle speed exceeds 3 mph (5 km/h) for 10 seconds when the SLS is
lowered.

REAR SUSPENSION
DESCRIPTION AND OPERATION 64-23
Transportation mode
Transportation mode must be used when the vehicle is transported on a trailer and secured by the chassis. The
transportation mode can only be enabled and disabled with TestBook.
The transportation mode lowers the rear suspension onto the bump stops with the engine not running. When the
suspension is in transportation mode, the SLS warning lamp is continuously illuminated when the ignition is in position
II.
When the engine is started in transportation mode, the SLS system will raise the rear suspension until a gap of 25
mm (1 in.) exists between the bump stop and the axle. The SLS warning lamp will flash continuously while the SLS
system is raising the suspension. When the gap between the bump stop and the axle is achieved, the warning lamp
will illuminate continuously.
When TestBook is used to disable the transportation mode, the rear suspension will raise to normal ride height when
the engine is running.

REAR SUSPENSION
REPAIRS 64-27
REPAIRS
Wheel hub
$% 64.15.01
Models with SLS:
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.Remove road wheel.
3.Release stake in drive shaft nut.
4.With an assistant depressing the brake pedal,
remove and discard drive shaft nut.
5.Remove rear brake disc.

+ BRAKES, REPAIRS, Brake disc -
rear.6.Disconnect ABS sensor multiplug.
7.Release harness from brake hose and hose
bracket.
8.Remove 4 bolts securing wheel hub to axle.
9.Release and remove wheel hub and drive shaft
assembly from axle. Remove and discard 'O'
ring from wheel hub.

REAR SUSPENSION
64-28 REPAIRS
10.Position the wheel hub and drive shaft on a
press, place supports beneath the wheel studs
and press the drive shaft from the wheel hub.
Refit
1.Clean drive shaft splines, wheel hub and axle
mating faces, ABS sensor and sensor recess.
2.Fit drive shaft to axle casing.
3.Lubricate new bearing hub 'O' ring with clean
differential oil.

+ CAPACITIES, FLUIDS,
LUBRICANTS AND SEALANTS,
Lubrication.
4.Fit 'O' ring to wheel hub.
5.Apply a 3 mm (0.125 in) wide bead of sealant,
Part No. STC 50554 around drive shaft
circumference as illustrated.
6.Fit wheel hub to drive shaft and align to axle.
The sealant will smear along the length of the
splines as the wheel hub is fitted to the drive
shaft.
7.Fit bolts securing wheel hub to axle and tighten
to 100 Nm (74 lbf.ft).
8.Fit new drive shaft nut and lightly tighten.
9.Fit rear brake disc.

+ BRAKES, REPAIRS, Brake disc -
rear.
10.With an assistant depressing the brake pedal,
tighten drive shaft nut to 490 Nm (360 lbf.ft).
Stake drive shaft nut. The drive shaft nut
must be tightened before the sealant has
cured.
11.Connect ABS sensor multiplug and secure
harness to harness bracket and brake hose.
12.Fit road wheel and tighten nuts to 140 Nm (103
lbf.ft).
13.Remove stand(s) and lower vehicle.
M51 0057
M51 0058

REAR SUSPENSION
REPAIRS 64-29
Road spring - rear
$% 64.20.01
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.Support vehicle under chassis.
3.Remove road wheel.
4.Support weight of axle on a jack.
5.Remove bolt securing damper to axle.
WARNING: Make sure the axle cannot move
when the damper is disconnected. The
damper limits the downward movement of
the axle. If the axle is not restrained,
disconnecting the damper will allow
unrestricted movement which may cause
personal injury or damage to equipment.
6.Remove clip securing brake pipe to bracket.
7.Release ABS sensor lead from bracket.
8.Lower axle on jack and remove spring.Refit
1.Ensure spring seats are clean.
2.Fit spring with close coil uppermost.
3.Ensure spring is correctly located on spring
seats and raise axle. Fit and tighten bolt
securing damper to axle to 124 Nm (91 lbf.ft).
4.Fit clip to secure brake pipe to bracket.
5.Fit ABS sensor lead to bracket.
6.Fit road wheel and tighten nuts to 140 Nm (103
lbf.ft).
7.Remove stand(s) and lower vehicle.

REAR SUSPENSION
64-30 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.
CAUTION: Check air bag for signs of
damage. If air bag is damaged, air spring
must be replaced.
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.Repressurise SLS air system using TestBook.
WARNING: Eye protection must be worn
during the repressurisation procedure.
7.Fit road wheel and tighten nuts to 140 Nm (103
lbf.ft).
8.Remove stand(s) and lower vehicle.

REAR SUSPENSION
REPAIRS 64-31
Damper - rear
$% 64.30.02
Remove
1.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.
2.Remove road wheel.
3.Support weight of axle on a jack.
4.Remove 2 bolts securing damper to axle and
chassis.
WARNING: Make sure the axle cannot move
when the damper is disconnected. The
damper limits the downward movement of
the axle. If the axle is not restrained,
disconnecting the damper will allow
unrestricted movement which may cause
personal injury or damage to equipment.
5.Compress damper and remove from vehicle.
Refit
1.Locate damper in axle and fit lower bolt, extend
damper to chassis and fit top bolt.
2.Tighten damper bolts to 125 Nm (92 lbf.ft).
3.Lower axle and remove jack.
4.Fit road wheel and tighten nuts to 140 Nm (103
lbf.ft).
5.Remove stand(s) and lower vehicle.
Bushes - radius arm
$% 64.35.29
Models with SLS:
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.Remove road wheel(s).
3. Models with SLS: Remove nut and bolt
securing height sensor link to radius arm.
4.Remove nut and bolt securing radius arm to
chassis.
5.Remove 2 nuts securing radius arm to axle.
6.Remove rear bolt and lower radius arm.

REAR SUSPENSION
REPAIRS 64-33
4.Position LRT-60-034/2 over radius arm and
locate bush to aperture.
5.With assistance, press bush into aperture.
6.Repeat above operation for remaining bush.
7.Position radius arm to vehicle and fit securing
nuts and bolts, do not tighten at this stage.
CAUTION: Nuts and bolts must be tightened
with the weight of the vehicle on the
suspension.
8. Models with SLS: Position height sensor link
to radius arm and tighten nut and bolt to 25 Nm
(18 lbf.ft).
9.Fit road wheel and tighten nuts to 140 Nm (103
lbf.ft).
10.Remove stands and lower vehicle.
11.Tighten radius arm nuts and bolts to 230 Nm
(170 lbf.ft).

REAR SUSPENSION
64-34 REPAIRS
Bushes - Watts linkage
$% 64.35.35
Models with SLS:
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.Remove 3 nuts and bolts securing Watts
linkage to axle and chassis and remove Watts
linkage.
3.Remove 2 nuts and bolts securing transverse
links to pivot housing and remove links from
pivot housing. 4.Use LRT-60-010/1 and LRT-60-010/3 to press
bushes from transverse links and pivot
housing.
Refit
1.Clean bush locations in transverse links and
pivot housing.
2.Using LRT-60-010/1 and LRT-60-010/2press
new bushes into transverse links and pivot
housing.
3.Position transverse links to pivot housing and
tighten bolts to 155 Nm (114 lbf.ft).
4.Position Watts linkage to axle and chassis. Fit
bolts but do not tighten at this stage.
5.Remove stand(s) and lower vehicle.
6.Tighten bolts securing pivot housing to axle to
230 Nm (170 lbf.ft). Tighten bolts securing
transverse links to chassis to 140 Nm (103
lbf.ft).
CAUTION: Nuts and bolts must be tightened
with weight of vehicle on suspension.

REAR SUSPENSION
REPAIRS 64-35
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.