2002 LAND ROVER DISCOVERY ABS

STEERING
DESCRIPTION AND OPERATION 57-5
Description
General
The major steering components comprise an impact absorbing telescopic steering column, a Power Assisted Steering
(PAS) box, a PAS pump, and fluid reservoir. Hydraulic fluid from the fluid reservoir is filtered and then supplied
through the suction line to the inlet on the PAS pump. The PAS pump supplies fluid to the steering box through a
pressure line routed above the front cross member. Fluid returns to the reservoir along the same route through a
return line. On LH drive vehicles the pipe route above the front cross member is still used, the length of pipe acting
as an oil cooler.
To minimise driver's injury in the event of an accident the steering system has a number of safety features including
a collapsible steering column. An additional safety feature is an air bag located in the steering wheel.

+ RESTRAINT SYSTEMS, DESCRIPTION AND OPERATION, Description - SRS.
Steering column assembly and intermediate shaft
The steering column central shaft comprises of two shafts, the upper shaft is splined to accept the steering wheel and
located in bearings in the column tube. A universal joint is located on the bottom of the upper shaft, the joint allows
for angular movement between the upper and lower shafts. The lower shaft is made in two parts, the top section of
the lower shaft is located outside of the lower section. The two sections of the lower shaft are connected by two nylon
injection moulded shear pins. The lower shaft goes through a lower bearing attached to the bulkhead, the lower shaft
is connected by a universal joint to the intermediate shaft in the engine compartment.
Steering column
An upper column tube provides for the location of the steering lock and ignition switch and also the steering switch
gear and a rotary coupler. The rotary coupler provides the electrical connection for the steering wheel mounted airbag,
switches and horn. The upper mounting bracket has two slots, a slotted metal bracket is held in each slot by four resin
shear pins.
The column is mounted on four captive studs which are located on a column mounting bracket. The captive studs
pass through the metal brackets, locknuts secure the steering column to the bulkhead. The two lower mountings are
fixed and cannot move when loads are applied to them. The upper mounting is designed to disengage or deform when
a load is applied, allowing the column to collapse in the event of an accident. The steering column must be replaced
as a complete assembly if necessary.
When an axial load is applied to the upper column tube, energy absorption is achieved by the following mechanism:
lthe mounting bracket deforms,
lthe resin shear pins holding the slotted metal brackets shear,
lthe top mounting bracket slides out of the slotted metal brackets.
The slotted metal brackets remain on the captive studs on the bulkhead. If the column mounting moves, injection
moulded shear pins retaining the two sections of the lower column shaft will shear. This allows the two sections of the
lower shaft to 'telescope' together.
In the event of a collision where the steering box itself moves, two universal joints in the column allow the intermediate
shaft to articulate, minimising movement of the column towards the driver. If movement continues energy absorption
is achieved by the following mechanism:
lthe decouple joint in the intermediate shaft will disengage,
lthe lower section of the steering column shaft will move through the lower bearing,
lthe injection moulded shear pins retaining the two sections of the lower column shaft will shear.
This allows the two sections of the lower shaft to 'telescope' together reducing further column intrusion. Protection to
the drivers face and upper torso is provided by an SRS airbag module located in the centre of the steering wheel.

+ RESTRAINT SYSTEMS, DESCRIPTION AND OPERATION, Description - SRS.

STEERING
57-14 DESCRIPTION AND OPERATION
The PAS pump is located on the auxiliary housing, two bolts go through the PAS pump, mounting bracket and into
the auxiliary housing. One bolt also attaches the mounting bracket to the PAS pump, two bolts secure the mounting
bracket to the auxiliary housing. An inlet adaptor pipe with a seal is secured to the bottom of the pump with two bolts.
A drive pulley is attached to the pump drive shaft with three bolts, and is belt driven at a ratio of 1.35 crankshaft
revolutions to 1 of the drive pulley. A coupling on the rear of the PAS pump rotates the water pump impeller located
in the auxiliary housing. Fluid is supplied to the PAS pump inlet from the reservoir through a flexible hose at low
(suction) pressure. Fluid at high pressure from the PAS pump outlet is supplied to the rotary control valve on the
steering box.
The PAS pump is a roller vane type and has an internal pressure regulator and flow control valve. The roller vanes
can move in slots in the pumps rotor and are moved outwards by centrifugal force as the pump rotates. The pump
rotor rotates in the pump housing, the internal shape of the housing forms a 'cam' shape. Due to the 'cam' shape the
volume of the housing decreases between the inlet and outlet ports.
As the pump rotor rotates towards the pump inlet the volume between the roller vanes and the pump housing
increases, this action causes a depression in the chamber between the pump roller vanes and the housing. As the
rotation continues the chamber is opened to the pump inlet, and the depression in the chamber causes fluid to be
drawn in. The roller vanes continue past the inlet port, closing off the inlet port and trapping the fluid in the chamber
between the rollers and the pump housing.
The internal 'cam' shape of the pump housing causes the rollers to move closer together as the pump rotor rotates
towards the outlet port. The reduced volume of the chamber between the roller vanes causes the fluid to become
pressurised. When the chamber is opened to the outlet port of the pump the fluid escapes at high pressure. The roller
vanes continue turning and go past the outlet port, closing off the chamber between the two roller vanes.
As rotation continues the inlet sequence begins again. The inlet and pressurisation/outlet sequences continue as the
pump rotates, and is repeated between each two roller vanes. The pump is a positive displacement type and the
potential pump output increases with engine (drive pulley) speed. The pressure relief and flow control valve regulates
flow/pressure by diverting fluid back to the pump inlet through internal recirculation passages in the pump body.
Steering damper
The steering damper is located behind and just below the first cross member of the chassis. The ends of the steering
damper have steel 'eyes' welded on, rubber bushes are installed in each 'eye'. The steering damper is attached
between brackets on the chassis rail and the drag link. Each end of the steering damper is secured by a bolt and
locknut. The hydraulic damper absorbs shocks in the steering, caused by road wheel deflections when operating on
rough terrain.

STEERING
57-22 ADJUSTMENTS
38.Fit new seal, connect PAS cooler pipe and
tighten union nut to 24 Nm (18 lbf ft).
39. LHD only: Fit turbocharger intercooler feed
pipe and vacuum connection. Fit new seal to air
cleaner. Connect air intake hose and secure
clips. Connect multiplug to MAF sensor.
40.Clean chassis and surrounding area.
41.Fit underbelly panel.

+ EXTERIOR FITTINGS, REPAIRS,
Panel - underbelly.
42.Remove adaptor and hose set from tool LRT-
57-041.
43.Check PAS fluid level.
44.Connect battery earth lead.
Power steering pressure check - V8 LHD
models
$% 57.90.10.01
Check
1.Disconnect battery earth lead.
2.Syphon PAS fluid from reservoir.
3.Raise front of vehicle and support on stands.
4.Turn steering on LH lock.
5.Remove 3 screws securing LH splash shield
and remove shield.
6.Release clip securing PAS pipes.
7.Position absorbent cloth to catch spillage.
8.Position container to collect PAS fluid spillage.

FRONT SUSPENSION
60-4 DESCRIPTION AND OPERATION
Description
General
The front suspension comprises two dampers and coil springs, two radius arms, a Panhard rod and an anti-roll bar.
The front axle provides the location points for the dampers, springs, radius arms and the Panhard rod.
The anti-roll bar assembly is an essential part of the front suspension. On vehicles without Active Cornering
Enhancement (ACE) a conventional 'passive' anti-roll bar is fitted. On vehicles fitted with the ACE system, a thicker
diameter anti-roll bar, known as a torsion bar, is used with an actuator at one end.

+ FRONT SUSPENSION, DESCRIPTION AND OPERATION, Description - ACE.
The hydraulic dampers and coil springs provide springing for each front wheel. The long travel dampers, springs and
radius arms provide maximum axle articulation and wheel travel for off-road driving. The front axle is controlled
longitudinally by two forged steel radius arms and transversely by a Panhard rod.
Radius arms
Each radius arm is manufactured from forged steel. Two bushes are pressed into the forward end of the radius arm.
The forward end of the radius arm is located in a fabricated bracket on the axle and secured through the bushes with
two bolts and nuts. A bush is pressed into the rear of the radius arm which is also located in a fabricated bracket on
each chassis longitudinal and secured through the bush with a bolt and nut.
The radius arms prevent longitudinal movement of the front axle and because of their length allow maximum axle
articulation. The stiffness of the bushes in each radius arm also contributes to the vehicle roll stiffness.
Each radius arm has a notch on its lower edge which provides location for the vehicle jack.
Dampers
Two conventional telescopic dampers are used to control body/axle movement. A turret is located on a bracket welded
to the chassis. The upper spring seat has four studs which pass through holes in the bracket and align with
corresponding holes in the turret. Four nuts are screwed onto the studs and secure the turret and upper spring seat
to the chassis.
A fabricated platform is welded to the axle. The platform has two captive nuts which provide for the attachment of the
damper. A lower spring seat is located on the platform. Each spring seat is handed and has a bracket which secures
the ABS sensor harness and the front brake hose.
Each damper is fitted with a bush at its upper end. The bush locates in the top of the turret and is secured with a cross
bolt. The lower attachment point for the damper is also fitted with a bush. This bush has a spindle through its centre
with a hole at each end. The spindle is seated on the lower spring seat and the axle platform and secured with two
bolts. The coil spring is fitted in a compressed state between the upper and lower spring seats and assists the damper
in controlling the body/axle movement. The upper and lower bushes are replaceable items.
Rubber bump stops are fitted to the chassis above each end of the axle. The bump stops are progressive in their
compression and prevent the axle from contacting the chassis in the event of maximum suspension travel being
reached. The bump stops revert to their original shape once the compression load has been removed from them.
The damper functions by restricting the flow of a hydraulic fluid through internal galleries within the damper body. A
chromium plated rod moves axially within the damper. As the rod moves, its movement is limited by the flow of fluid
through the galleries thus providing damping of undulations in the terrain. The damper rod is sealed at its exit point
from the body to maintain fluid within the unit and prevent the ingress of dirt and moisture. The seal also acts as a
wiper to keep the rod outer diameter clean. A plastic shroud protects the rod and slides over the body as the damper
moves. The coil spring aids the damper to extend after being compressed and also aids the damping process.

FRONT SUSPENSION
60-10 DESCRIPTION AND OPERATION
ACE system control diagram
1Upper accelerometer
2Lower accelerometer
3Pressure transducer
4Directional control valve
5Directional control valve
6Pressure control valve
7Instrument pack warning lamp
8Diagnostic socket9Reverse lamp switch
10SLABS ECU
11Engine Control Module (ECM)
12Ignition feed
13ACE relay
14Battery supply
15ACE ECU
M60 0589B
12
5
4
3
6
7
8
9
10
11
12
13
14
15

FRONT SUSPENSION
DESCRIPTION AND OPERATION 60-21
A road speed signal is transmitted to the ACE ECU as a pulsed digital signal from the Self-levelling/Anti-lock Braking
System (SLABS) ECU. The road speed signal is used by the ACE ECU for on and off-road roll compensation.
When reverse gear is selected, an input is received from the reverse lamp switch. When the ACE ECU detects that
reverse gear has been selected, the ACE system reverts to a 'locked bars' condition until reverse gear is disengaged.
The diagnostic connection allows diagnostic interrogation of the ACE ECU. The diagnostic socket allows diagnostic
equipment to be connected to interrogate the ACE ECU for fault codes.
When system faults are detected by the ECU, the ACE warning lamp in the instrument pack is illuminated by the ECU
continuously in amber for minor faults or flashing red with an audible warning for faults which require the driver to stop
the vehicle immediately.
The ACE ECU supplies a control current to the pressure control valve in the valve block. The current supplied by the
ECU is determined by a number of input signals from the upper and lower accelerometers, road speed etc.. The
pressure control valve controls the hydraulic pressure supplied to the actuators proportional to the current supplied
by the ECU.
Power is supplied to the two solenoid operated directional control valves (DCV's) in the valve block by the ECU.
Together, the DCV's control the direction of flow of hydraulic fluid to the actuators. When the ECU supplies power to
the solenoids the valves open allowing hydraulic fluid to flow to the actuators. When power is removed the valves
close.
The pressure transducer in the valve block receives a 5 V supply from the ECU. The pressure transducer measures
hydraulic pressures in the range of 0 to 180 bar (0 to 2610 lbf.in
2) and returns a linear output voltage to the ECU
dependent on hydraulic pressure.
The ECU supplies a 5 V current to each of the accelerometers. Each accelerometer is capable of measuring lateral
acceleration in the range of
± 1.10 g. An analogue input to the ECU of between 0.5 and 4.5 V relative to the lateral
acceleration sensed is returned by each accelerometer. The ECU processes the two signals received to produce a
'pure' lateral acceleration signal which is then used as the main control signal for the ACE system.
ACE ECU connector pin details
Pin No. Description Input/Output
1 Not used -
2 Not used -
3SpareInput
4 Not used -
5 Road speed Input
6 ARC relay Output
7 to 9 Not used -
10 K line (diagnostics) -
11 Ignition switch Input
12 Accelerometer - lower (supply) Output
13 Pressure transducer (supply) Output

FRONT SUSPENSION
60-30 REPAIRS
Ball joint - upper - steering knuckle
$% 60.15.02
CAUTION: Each ball joint can be replaced up to
three times before the axle yoke bore becomes
oversize. Before commencing work, thoroughly
clean surface of joint and check for yellow paint
marks approx. 12 mm (0.5 in) wide. If 3 marks are
found, the axle case must be renewed.
Remove
1.Remove steering knuckle.

+ FRONT SUSPENSION, REPAIRS,
Steering knuckle.
2.Support the chassis on stands.
3.Support the front axle on stands.
4.Remove 2 nuts securing anti-roll bar lower links
to front axle, use a 16 mm spanner to prevent
link joint from turning.
5.Remove 2 bolts securing each front damper to
axle.
6.Remove 8 bolts securing chassis crossmember
and remove crossmember.
7.Remove bolt securing brake hose and ABS
sensor harness bracket to axle.
8.Lower the front axle, release front spring from
damper and remove front spring.9.Fit tool LRT-54-008/22 to tool LRT-54-008.
10.Fit tool LRT-54-008/4 to tool LRT-54-008, and
secure with screw.
11.Fit tool LRT-54-008 with all attachments to
upper ball joint..
12.Fit tool LRT-54-008/5 to the top of the ball
joint.
13.Press upper ball joint from axle. When ram lead
screw reaches the end of its stroke, retract the
lead screw and screw the ram further into the
tool. Repeat the operation until the ball joint is
released from the axle.
14.Dismantle the tools.
Refit
1.Clean upper ball joint location and surrounding
area of axle yoke.
2.Apply a 12 mm (0.5 in) wide yellow paint stripe
on axle yoke, adjacent to upper ball joint
location.

FRONT SUSPENSION
60-34 REPAIRS
Road spring - front
$% 60.20.11
Remove
1.Raise front 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 front road wheels.
4.Support weight of front axle.
5.Remove 2 nuts securing anti-roll bar links to
front axle and disconnect links from axle.
6.Remove 2 bolts securing each damper to front
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.
7.Lower front axle.
CAUTION: Ensure brake hoses and ABS
sensor harnesses are not damaged when
lowering front axle.
8.Release and remove front spring from damper.Refit
1.Clean front spring seats.
2.Position front spring, with close coil uppermost,
over damper and locate in cut out in lower
spring seat.
3.Ensure both front springs are correctly located
in spring seats and raise front axle. Fit bolts
securing both dampers to front axle and tighten
to 45 Nm (33 lbf.ft).
4.Ensure washer is in place on lower ball joint of
each anti-roll bar link, then connect lower ball
joints to axle. Tighten nuts to 100 Nm (74 lbf.ft).
5.Fit front road wheels and tighten nuts to 140
Nm (103 lbf.ft).
6.Remove stands and lower vehicle.