2002 LAND ROVER DISCOVERY service

FRONT SUSPENSION
DESCRIPTION AND OPERATION 60-13
Lateral acceleration of the body is sensed by two accelerometers and signals are transmitted to the ECU. The engine
driven hydraulic pump supplies a constant hydraulic flow to the valve block. Two directional control valves are
solenoid operated by the ECU and these supply fluid to the applicable side of each actuator to apply an equal and
opposite force to the torsion bar. In operation the ACE system maintains the attitude of the vehicle body when
cornering.
The ACE system uses a semi-synthetic hydraulic fluid which is the same as the fluid used for the PAS system. The
total capacity of the ACE system is 1.62 litres (0.42 US Gallons).
CAUTION: The ACE hydraulic system is extremely sensitive to the ingress of dirt or debris. The smallest
amount could render the system unserviceable. It is imperative that the following precautions are taken.
lACE components are thoroughly cleaned externally before work commences;
lall opened pipe and module ports are capped immediately;
lall fluid is stored in and administered through clean containers.
In the event of an ECU or hydraulic failure the system will fail safe to a 'locked bars' condition. The 'locked bars'
condition will allow the torsion bars to operate in a similar manner as conventional 'passive' anti-roll bars. Prolonged
cornering forces will allow a progressive increase in roll angle due to hydraulic leakage through the actuators and
valve block. Failures will be relayed to the driver by the illumination of the ACE warning lamp in the instrument pack.
Faults are recorded by the ECU and can be retrieved using TestBook.
When the ignition switch is moved to position II, the warning lamp will illuminate for two seconds to check functionality.
The warning lamp functionality can also be checked using TestBook.
TestBook must also be used to perform a bleeding procedure after maintenance operations have been performed to
ensure that complete system bleeding is performed. Trapped air in the system can seriously reduce the system
performance.
Fluid reservoir
The moulded plastic fluid reservoir is mounted on the left hand side of the engine compartment on a bracket which is
attached to the inner wing. The reservoir is dual purpose, being divided into two separate chambers; one for the ACE
system and one for the PAS system. Each chamber has its own filler neck and cap and is identified by moulded
lettering on the reservoir adjacent to each filler.
A non-serviceable filter assembly is fitted in the base of each chamber. The filter is made from fine stainless steel
mesh which is moulded into the body of the reservoir. The filter removes particulate matter from the fluid before it is
drawn into the hydraulic pump.
Upper and lower fluid level marks are moulded onto the reservoir body. The capacity of the ACE reservoir chamber
to the upper level mark is 0.5 litre (0.13 US Gallon).

FRONT SUSPENSION
DESCRIPTION AND OPERATION 60-15
As the cam lobe moves away from the piston, a spring pushes the piston down the bore creating a vacuum above the
piston. As the piston moves down the bore, ports in the piston are exposed and connect with the fluid inlet. The
vacuum draws fluid into the piston filling the piston and the chamber above it. As the piston is again pushed upwards,
the ports are closed off by the bore and the fluid opens the discharge valve and flows to the outlet port.
The above sequence is applied to each of the six pistons for every revolution of the central shaft and cam. When the
engine is running the sequence occurs rapidly creating a constant flow of fluid. The fluid flow varies with the engine
speed and the rotational speed of the central shaft. The pressure felt at the actuator, created by the flow from the
pump, is controlled by the pressure control valve in the valve block.
The pump has a displacement of 8.5 cm
3/rev and an operational pressure of 135 bar (1958 lbf.in2). The pump output
flow ranges from 7.0 l/min (1.85 US Gallons/min) at 775 rev/min to 9.25 l/min (2.44 US Gallons/min) at 7625 rev/min.
System pipes
Fluid is moved through the ACE system via a series of pipes and hoses. The pipes are mounted on brackets at
strategic points to assure quiet operation of the system.
The pipes from the pump to the valve block and from the valve block to the reservoir are one piece items which are
fitted at the factory before the body is attached to the chassis. If these pipes require replacement in service, the pipes
must be cut to facilitate their removal. 'In service' replacement pipes are available in two parts with a connector to seal
the joint.
The flexible hose which supplies pressure from the pump to the supply pipe attached to the front cross member is
fitted with an attenuator. The attenuator comprises a bullet shaped valve which is located between two spiral wound
springs held at each end of the flexible hose. This valve operates as a restrictor to damp pressure waves of hydraulic
fluid from the pump, reducing noise and strain on components downstream. The attenuator is integral with the supply
hose and pipe and cannot be serviced separately.

FRONT SUSPENSION
DESCRIPTION AND OPERATION 60-17
The valve block directs hydraulic pressure to the actuators via solenoid operated directional control valves. A solenoid
operated pressure control valve regulates the required pressure to the actuators. The three valve solenoids are
controlled by signals received from the ACE ECU. A pressure transducer monitors the pressure delivered by the
pump. A replacable high pressure filter is installed into the lower face of the valve block and filters fluid before it
reaches the valves.
The valve block is located on the outside of the right hand chassis longitudinal. The valve block is secured to the
chassis with three bolts and rubber bushes. The rubber bushes isolate the valve block from the chassis, preventing
hydraulic noise from the valve block transmitting through the chassis and body.
The two solenoid operated directional control valves (DCV's) are fitted to ports in the top face of the valve block. The
DCV's are screwed into the valve block and sealed with O ring seals. Each DCV has a solenoid for electrical operation
of the valve. The solenoid is sealed to the DCV with two O ring and secured with a cap. The cap, coil and O rings are
serviceable items. The DCV's are non-serviceable and failure of a DCV requires the replacement of the valve block
assembly.
The pressure control valve is fitted to a port in the rear face of the valve block. The pressure control valve is screwed
into the valve block and sealed with O rings. The pressure control valve has a coil for electrical operation. The coil is
sealed to the pressure control valve with two O rings and secured with a cap. The cap, coil and O rings are serviceable
items. The pressure control valve is non-serviceable and failure requires replacement of the valve block assembly.
The pressure transducer is fitted to a port in the forward face of the valve block. The pressure transducer is screwed
into the valve block and sealed with an O ring seal. The pressure transducer is a serviceable item.
The high pressure filter locates in a port on the lower face of the valve block. The gauze and fibre filter is sealed in
the port with O ring seals. A threaded cap secures the filter in the valve block and is also sealed with an O ring seal.
A threaded hole on the lower face of the filter allows a bolt to be fitted to remove the filter from the port. If a system
component is replaced, the filter must be changed.
Four ports are located on the forward face of the valve block and two ports on the rear. Each port is fitted with a seal
pack which contains two O ring seals and backing rings. The ACE pipes locate and seal in the seal packs and are
secured to the valve block with the studs and nuts located on the forward and rear faces.
Actuators
Two actuators are used for the ACE system and are attached to the front and rear torsion bars. The actuators apply
hydraulically generated force to the torsion bar to oppose lateral forces caused by the vehicle cornering.
Each actuator is a conventional double-acting cylinder. A piston is attached to a rod and moves within the cylinder
when hydraulic pressure is applied. The rod is sealed at the point where it exits the cylinder. The outer end of the rod
is threaded and locates in a bush in the ACE long arm and secured with a nut. A rubber gaiter covers the rod and
prevents dirt and moisture from damaging the rod surface and cylinder seals. The cylinder has a forked attachment
which locates on the short arm bush and secured with a bolt and nut.
Two banjo connections provide for the attachment of the hydraulic hoses from the ACE valve block. The connections
provide hydraulic flow to each side of the piston to extend or retract the rod.

FRONT SUSPENSION
DESCRIPTION AND OPERATION 60-19
The right hand end of the torsion bar has a machined spigot which provides for the attachment of the forged steel
short and long arms. The spigot for the short arm is splined and mates with splines in the short arm. The short arm is
located in a specific position on the splines and clamped to the spigot with a Torx bolt and locknut. The short arm is
not a serviceable item other than the actuator attachment bush. The smaller spigot diameter locates the long arm.
The long arm is fitted with a slipper bush which is located on the spigot and secured with a large washer and a special
bolt. The slipper bush comprises two inner and two outer bushes which are installed from each side of the long arm.
The outer bushes have three lugs which locate in the long arm to prevent the bush from rotating. The long arm also
provides the attachment point for the actuator piston rod and the anti-roll bar link.
The actuator has a forked end which locates on the bush in the short arm and is secured with a bolt and nut. The
piston rod of the actuator locates through a hole in a cast boss on the long arm which is fitted with a special bush. A
shoulder on the piston rod seats in a hole in the bush and a locknut on the end of the piston rod secures the rod to
the long arm and bush.
The front torsion bar is attached to the front chassis cross member. Two rubber bushes are fitted to the torsion bar
and are located in clamp plates. The clamp plates are located in slots in the cross member and secured with bolts.
The rear torsion bar is attached to the tubular cross member at the rear section of the chassis. Two rubber bushes
are fitted to the torsion bar and are located in clamp plates. The clamp plates are located in fabricated brackets
attached to the tubular cross-member and secured with bolts.
Two anti-roll bar links are mounted on brackets on the front and rear axles. Each anti-roll bar link is fitted with a
spherical bearing at each end. One bearing is attached to the link at a 90
° angle. The threaded shank of the bearing
is located through a hole in a bracket on the axle and secured with a locknut; a washer is installed on the threaded
shank between the bearing and the bracket. The second spherical bearing is attached in-line with the link and locates
in the torsion bar on the left hand side and the long arm on the right hand side. The front anti-roll bar links are longer
than the rear links and are not interchangeable.
Accelerometers
Two accelerometers are used for the ACE system. The upper accelerometer is mounted on a bracket, behind the
headlining adjacent to the rear view mirror and the sunroof ECU. The lower accelerometer is located on a bracket on
the inner sill panel under the RH front floor.
The lower accelerometer is the primary sensor used to measure lateral acceleration of the vehicle for roll control. The
upper accelerometer is used by the ECU for roll correction and fault detection in conjunction with the lower
accelerometer.
Each accelerometer is a solid state capacitive acceleration sensor and operates on a 5 V supply from the ECU. The
upper and lower sensors can measure acceleration in the range of
± 1.10 g and return an output to the ECU of
between 0.5 and 4.5 V.
Failures of an accelerometer are recorded by the ECU and can be retrieved using TestBook. A special tool is required
to remove and replace a sensor in the bracket.

FRONT SUSPENSION
ADJUSTMENTS 60-27
ADJUST ME NTS
ACE hydraulic system bleeding
$% 60.60.13
Introduction
CAUTION: The ACE hydraulic system is
extremely sensitive to the ingress of dirt or
debris. The smallest amount could render the
system unserviceable. It is imperative that the
following precautions are taken.
lACE components are thoroughly cleaned
externally before work commences;
lall opened pipe and module ports are
capped immediately;
lall fluid is stored in and administered
through clean containers.
Check
1.Check the ACE system fluid level.

+ FRONT SUSPENSION,
ADJUSTMENTS, Fluid level check - ACE
system.
Bleed
1.With vehicle on ramp, connect TestBook and
follow bleed procedure as described.
Fluid level check - ACE system
$% 60.60.14
Introduction
CAUTION: The ACE hydraulic system is
extremely sensitive to the ingress of dirt or
debris. The smallest amount could render the
system unserviceable. It is imperative that the
following precautions are taken.
lACE components are thoroughly cleaned
externally before work commences;
lall opened pipe and module ports are
capped immediately;
lall fluid is stored in and administered
through clean containers.
Check
1.Clean reservoir around fluid level marks.
2.Visually check fluid level through side of
reservoir. Fluid level must be between upper
and lower fluid level marks.
Top-up
1.Clean reservoir around filler cap.
2.Remove filler cap from reservoir and fill to
upper fluid level mark with recommended fluid.

+ CAPACITIES, FLUIDS AND
LUBRICANTS, Fluids.
3.Fit filler cap to reservoir
4.Start and run engine for 2 minutes to circulate
fluid.
5.If necessary, top-up reservoir to upper fluid
level mark.

FRONT SUSPENSION
REPAIRS 60-41
6.Remove 3 nuts securing ACE ECU and remove
ACE ECU.
Refit
1.Fit ACE ECU to bracket and secure with nuts.
2.Fit ECU's and bracket assembly to body and
secure with nuts.
3.Connect multiplugs to ACE ECU and SLABS
ECU.
4.Fit BCU.

+ BODY CONTROL UNIT, REPAIRS,
Body control unit (BCU).
5.If a replacement ACE ECU has been fitted, use
TestBook to calibrate ACE system.
Accelerometer - ACE - upper
$% 60.60.02
CAUTION: The accelerometer is an extremely
delicate component and can easily be rendered
unserviceable. Never use an accelerometer
which has been dropped or subjected to
mistreatment of any type.
Remove
1.Remove front stowage pocket.

+ INTERIOR TRIM COMPONENTS,
REPAIRS, Stowage pocket - front.
2.Disconnect multiplug from accelerometer.
3.Use LRT-60-014A to release clip and remove
accelerometer.
Refit
1.Using LRT-60-014A, fit accelerometer fully into
clip.
2.Connect accelerometer multiplug.
3.Fit front stowage pocket.

+ INTERIOR TRIM COMPONENTS,
REPAIRS, Stowage pocket - front.
4.If a replacement accelerometer has been fitted,
use TestBook to calibrate ACE system.

FRONT SUSPENSION
60-42 REPAIRS
Accelerometer - ACE - lower
$% 60.60.03
CAUTION: The accelerometer is an extremely
delicate component and can easily be rendered
unserviceable. Never use an accelerometer
which has been dropped or subjected to
mistreatment of any type.
Remove
1.Raise vehicle on a ramp.
2.Disconnect multiplug from accelerometer.
3.Use LRT-60-014A to release clip and remove
accelerometer.
Refit
1.Use LRT-60-014A, fit accelerometer fully into
clip.
2.Connect accelerometer multiplug.
3.Lower vehicle.
4.If a replacement accelerometer has been fitted,
use TestBook to calibrate ACE system.
Pump - ACE - V8
$% 60.60.10
CAUTION: The ACE hydraulic system is
extremely sensitive to the ingress of dirt or
debris. The smallest amount could render the
system unserviceable. It is imperative that the
following precautions are taken.
lACE components are thoroughly cleaned
externally before work commences;
lall opened pipe and module ports are
capped immediately;
lall fluid is stored in and administered
through clean containers.
Remove
1.Remove auxiliary drive belt.

+ CHARGING AND STARTING,
REPAIRS, Belt - auxiliary drive.
2.Loosen 3 clips securing air intake hose.
Release air intake hose and position aside.
Note: Pre 03 MY air intake hose illustrated.

FRONT SUSPENSION
60-44 REPAIRS
Pump - ACE - diesel
$% 60.60.10
CAUTION: The ACE hydraulic system is
extremely sensitive to the ingress of dirt or
debris. The smallest amount could render the
system unserviceable. It is imperative that the
following precautions are taken.
lACE components are thoroughly cleaned
externally before work commences;
lall opened pipe and module ports are
capped immediately;
lall fluid is stored in and administered
through clean containers.
Remove
1.Remove auxiliary drive belt.

+ CHARGING AND STARTING,
REPAIRS, Belt - auxiliary drive.
2.Disconnect multiplugs from mass air flow
sensor and ambient air pressure sensor.
3.Release clips and disconnect mass air flow
sensor from air cleaner.
4.Loosen hose clip, disconnect inlet air hose
from turbo charger and move hose aside. 5.Release ACE/PAS reservoir from bracket and
move aside.
6.Loosen clip and disconnect inlet hose from
intercooler.
7.Position container to catch spillage.