2002 LAND ROVER DISCOVERY tow

AUTOMATIC GEARBOX - ZF4HP22 - 24
44-18 DESCRIPTION AND OPERATION
With time, the components in a gearbox wear and the duration of the gear shifts tends to increase, which has an
adverse effect on the brake clutches. To counteract this, the EAT ECU applies a pressure adaptation to each shift.
To calculate the adaptations, the EAT ECU monitors the pressure modulation used, and time taken, for each shift. If
a subsequent shift of the same type, in terms of throttle position and engine speed, has a longer duration, the EAT
ECU stores an adaptation for that type of shift in a volatile memory. The adaptation is then included in future pressure
calculations for that type of shift, to restore shift duration to the nominal.
Kickdown
The EAT ECU monitors the input of the throttle position sensor to determine when kickdown is required. When it
detects a kickdown situation, the EAT ECU immediately initiates a down shift provided the target gear will not cause
the engine speed limit to be exceeded.
Torque converter lock-up
The EAT ECU energises the lock-up solenoid valve to engage the lock-up clutch. Lock-up clutch operation is
dependent on throttle position, engine speed, operating mode and the range selected on the transfer box.
High range
Unique lock-up maps, similar to the shift maps, are incorporated in the economy and sport modes for all forward gears.
Engagement and disengagement of the lock-up clutch is dependent on throttle position and engine speed.
Low range
To enhance off road control, particularly when manoeuvring at low speeds, torque converter lock-up does not occur
when there is any degree of throttle opening. When the throttle is closed above a preset engine speed, the lock-up
clutch engages to provide maximum engine braking.
Increased load/reduced torque compensation
To aid performance and driveability in the high range economy mode, the EAT ECU has three adaptive shift and lock-
up maps. These maps delay upshifts and torque converter lock-up similar to the sport mode if the inputs from the
engine indicate:
lA sustained high load on the engine, such as occurs when the vehicle is ascending a steep gradient or towing a
trailer.
lA lower than normal engine torque, such as occurs at altitude or high ambient temperatures.
The EAT ECU monitors the engine inputs and selects the most appropriate adaptive map for the prevailing conditions.
Diagnostics
While the ignition is on, the EAT ECU diagnoses the system for faults. The extent of the diagnostic capability at any
particular time depends on the prevailing operating conditions, e.g. it is not possible to check torque converter lock-
up while the vehicle is stationary, or to check for a short circuit to earth if the circuit concerned is already at a low
potential.
If a fault is detected, the EAT ECU immediately stores a fault code and the values of three operating parameters
associated with the fault. Depending on the fault, there are four possible effects:
lThe fault has little effect on gearbox operation or vehicle emissions. The driver will probably not notice any
change and the warning lamps remain extinguished.
lThe fault has little effect on gearbox operation but may effect vehicle emissions. On NAS vehicles, if the fault is
detected on a second consecutive drive cycle, the MIL illuminates.
lAll gears are available but kickdown does not function. The sport and manual warning lamps flash. The MIL
remains extinguished.
lLimp home mode is selected and vehicle performance is greatly reduced. The sport and manual warning lamps
flash. In all markets, if the fault is detected on a second consecutive drive cycle, the MIL illuminates.

AUTOMATIC GEARBOX - ZF4HP22 - 24
44-46 REPAIRS
7.Remove temperature sensor and discard
sealing washer.
Refit
1.Use new sealing washer and tighten
temperature sensor to 14 Nm (10 lbf.ft).
2.Fit cooler, engage with radiator and secure with
screw.
3.Connect temperature sensor multiplug.
4.Ensure connections are clean and fit hoses to
cooler.
5.Fit intercooler.

+ ENGINE MANAGEMENT SYSTEM -
Td5, REPAIRS, Intercooler.
6.Check and if necessary top up gearbox fluid.
Cooler - fluid - V8
$% 44.24.10
Remove
1. If fitted: Remove engine oil cooler.

+ ENGINE - V8, REPAIRS, Cooler -
engine oil.
2.Disconnect fluid temperature sensor multiplug.
3.Position absorbent cloth under each gearbox
cooler hose connection to collect spillage.
4.Push against coupling release ring and
disconnect both fluid hoses from cooler.
CAUTION: Always fit plugs to open
connections to prevent contamination.
5.Remove screw and release cooler from
radiator.
6.Carefully move radiator towards engine and
remove cooler.

AUTOMATIC GEARBOX - ZF4HP22 - 24
REPAIRS 44-51
Lock-up solenoid valve (MV 3)
$% 44.15.35
Remove
1.Remove valve body assembly.

+ AUTOMATIC GEARBOX - ZF4HP22
- 24, REPAIRS, Valve body assembly.
2.Disconnect multiplug from lock-up solenoid
valve and release harness from clip.
3.Remove Torx screw and retaining fork securing
solenoid valve to valve body.
4.Remove solenoid valve from valve body.
Refit
1.Clean lock-up solenoid valve with lint free cloth.
2.Position solenoid valve in valve body.
3.Position retaining fork, fit and tighten Torx
screw to 8 Nm (6 lbf.ft).
4.Connect multiplug to lock-up solenoid valve
and secure harness in clip.
5.Fit valve body assembly.

+ AUTOMATIC GEARBOX - ZF4HP22
- 24, REPAIRS, Valve body assembly.
Solenoids - shift control valves (MV 1 &
2)
$% 44.15.45
Remove
1.Remove valve body assembly.

+ AUTOMATIC GEARBOX - ZF4HP22
- 24, REPAIRS, Valve body assembly.
2.Remove 3 Torx screws securing lock-up
solenoid valve assembly to valve body and
move solenoid aside.
NOTE: This is to gain access to remove Torx
screw and MV2 shift control valve.
3.Note their fitted position and disconnect
multiplugs from shift control valves MV 1 and
MV 2.
4.Remove Torx screw and retaining fork securing
MV2 shift control solenoid valve to valve body.
Note that the tag on the retaining fork faces
towards the valve body.
5.Remove shift control valve from valve body.
M44 1354A
2
3
4
M44 13521
M44 1353A

REAR AXLE
51-14 OVERHAUL
47.Tighten bearing cap bolts to 90 Nm (66.5 lbf.ft).
48.Secure adjusting nuts with new roll pins.
49.Apply Prussian Blue to crown wheel teeth to
check tooth contact.
50.Rotate pinion several times to obtain full tooth
contact.51.A = Normal pattern, the drive pattern should be
centred on the gear teeth. The coast pattern
should be centred on the gear teeth but may be
towards the toe. There should be some
clearance between the pattern and the top of
the gear teeth.
52.B = Backlash correct, thinner pinion shim
required.
53.C = Backlash correct, thicker pinion shim
required.
54.D = Pinion shim correct, decrease backlash.
55.E = Pinion shim correct, increase backlash.
56.Note assembly Torque to Turn when checking
tooth contact. Total Torque to Turn should not
exceed 10.85 Nm (8 lbf.ft).
Reassembly
1.Fit differential assembly.

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
DESCRIPTION AND OPERATION 57-13
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.
PAS pump - diesel
1Drive pulley
2Mounting bracket
3Bolt 2 off
4Bolt
5PAS pump
6Coupling7Auxiliary housing
8Outlet
9Inlet adaptor pipe and seal
10Bolt 2 off
11Bolt 2 off
12Bolt 3 off

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.

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.