1999 LAND ROVER DISCOVERY transmission fluid

CONTENTS
12 CONTENTS
AUTOMATIC GEARBOX - ZF4HP22 - 24 ................................................ 44-1
DESCRIPTION AND OPERATION
Automatic gearbox component layout ............................................................................................ 44-1
Control schematic ........................................................................................................................... 44-2
Description ...................................................................................................................................... 44-4
Operation ........................................................................................................................................ 44-17
ADJUSTMENTS
Cable - selector ............................................................................................................................. 44-21
Stall test .......................................................................................................................................... 44-21
REPAIRS
Cable and lever assembly - selector .............................................................................................. 44-23
Selector indicator .......................................................................................................................... 44-24
Switch - starter inhibitor ................................................................................................................. 44-25
Seal - selector shaft ........................................................................................................................ 44-26
Gearbox - convertor and transfer gearbox - Diesel ....................................................................... 44-27
Gearbox - convertor and transfer gearbox - V8 ............................................................................ 44-32
Torque converter and oil seal ......................................................................................................... 44-37
Housing - torque converter ............................................................................................................ 44-38
Gasket - intermediate plate ............................................................................................................ 44-39
Intermediate plate .......................................................................................................................... 44-41
Pump - fluid .................................................................................................................................... 44-43
Seal - rear extension housing ......................................................................................................... 44-44
Gasket - rear extension housing. .................................................................................................. 44-45
Parking pawl assembly. ................................................................................................................ 44-46
Gasket - oil sump ........................................................................................................................... 44-47
Filter - oil ........................................................................................................................................ 44-48
Cooler - fluid - Td5 .......................................................................................................................... 44-49
Cooler - fluid - V8 ........................................................................................................................... 44-50
Valve body assembly ..................................................................................................................... 44-51
Seal - valve body ........................................................................................................................... 44-53
Pressure regulator ......................................................................................................................... 44-54
Lock-up solenoid valve (MV 3) ...................................................................................................... 44-55
Solenoids - shift control valves
(MV 1 & 2) 44-56
Harness - solenoid valves .............................................................................................................. 44-57
Electronic control unit - automatic transmission ............................................................................. 44-58
PROPELLER SHAFTS ............................................................................. 47-1
DESCRIPTION AND OPERATION
Propeller shaft component layout ................................................................................................... 47-1
Description ...................................................................................................................................... 47-2
REPAIRS
Propeller shaft - front ..................................................................................................................... 47-5
Propeller shaft - rear ...................................................................................................................... 47-5
Bush - spigot - rear propeller shaft ................................................................................................ 47-6
Flexible coupling ............................................................................................................................ 47-7
OVERHAUL
Propeller shaft................................................................................................................................. 47-9

GENERAL INFORMATION
03-27
Body Repairs
General
Body shells are of welded construction and bolted to
a chassis frame. Front and rear sections of the shell
are designed as 'energy absorbing' zones. This
means they are designed to deform progressively
when subjected to impact in order to minimise the
likelihood of injury to vehicle occupants.
It is essential that design dimensions and strength
are restored in accident rectification. It is important
that neither structural weakness nor excessive local
stiffness are introduced into the vehicle during body
repair.
Repairs usually involve a combination of operations
ranging from straightening procedures to renewal of
individual panels or panel assemblies. The repairer
will determine the repair method and this decision will
take into account a balance of economics between
labour and material costs and the availability of repair
facilities in both equipment and skills. It may also
involve considerations of the vehicles' downtime,
replacement vehicle availability and repair turn-
around time.
It is expected that a repairer will select the best and
most economic repair method possible, making use
of the facilities available. The instructions given are
intended to assist a skilled body repairer by
expanding approved procedures for panel
replacement. The objective is to restore the vehicle
to a safe running condition by carrying out a repair
which is as close as is feasible to original standard.
The results should not advertise to the experienced
eye that the vehicle has been damaged, although the
repair might not be identical in all respects to the
original factory build. Commercial bodyshop repair
facilities cannot always duplicate methods of
construction used during production.
Operations covered in this Manual do not include
reference to testing the vehicle after repair. It is
essential that work is inspected and suspension
geometry checked after completion. Where
necessary a road test of the vehicle should be carried
out, particularly where safety-related items are
concerned.
Where major units have been disconnected or
removed it is necessary to ensure that fluid levels are
checked and topped up where necessary. It is also
necessary to ensure that the repaired vehicle is in a
roadworthy condition in respect of tyre pressures,
lights, washer fluid etc. Body repairs often involve the removal of mechanical
and electrical units and associated wiring. Where
necessary, refer to the relevant section of the
Workshop Manual for removal and refitting
instructions.
Taking into consideration the differences in body
styles, suspension systems and engine and
transmission layouts, the location of the following
components as applicable to a particular vehicle is
critical:
lFront suspension upper damper mountings on
RH and LH chassis longitudinals.
lFront suspension or sub frame mountings.
lEngine mountings on RH and LH chassis
longitudinals.
lRear suspension upper damper mountings on
RH and LH chassis longitudinals.
lRear suspension mountings or lower pivots.
Additional points which can be used to check
alignment and assembly are:
lInner holes in cross member - side - main floor.
lHoles in front bulkhead.
lHoles in rear longitudinals.
lHoles in rear lower panels.
Apertures for windscreen, rear screen, bonnet and
doors can be measured and checked using the
dimensional information provided and also by
offering up an undamaged component as a gauge.
Straightening
Whenever possible, structural members should be
cold straightened under tension. Do not attempt to
straighten with a single pull but rework the damaged
area using a series of pulls, releasing tension
between each stage and using the opportunity to
check alignment.
Body jig
Unless damage is limited to cosmetic panels, all
repair work to body members must be carried out on
a body jig, to ensure that impact damage has not
spread into more remote parts of the structure.
Mounting on a jig will also ensure that the
straightening and panel replacement procedures do
not cause further distortion.
If original dimensions cannot be satisfactorily
restored by these methods, damaged structural
members should be replaced. Damaged areas
should be cut away using a high speed saw, NOT an
oxy-acetylene torch.
As a rule, body dimensions are symmetrical about
the centre line. A good initial check for distortion is
therefore to measure diagonally and to investigate
apparent differences in dimensions.

AUTOMATIC GEARBOX - ZF4HP22 - 24
DESCRIPTION AND OPERATION 44-1
AUTOMATIC GE ARBOX - ZF4HP22 - 24 DESCRIPTION AND OPERAT ION
Automatic gearbox component layout
1Selector lever assembly
2Gearbox
3Electronic automatic transmission ECU
4Selector position switch5Oil cooler
6Fluid lines
7Breather tube
8Selector cable

AUTOMATIC GEARBOX - ZF4HP22 - 24
DESCRIPTION AND OPERATION 44-3
1Transmission high/low switch
2Mode switch
3Gear position switch connector
4Solenoid valve/speed sensor connector
5Electronic automatic transmission ECU
6Engine control module
7Diagnostic socket
8Instrument pack
9Transmission fluid temperature sensor
10Body control unit
11Battery power supply
12Ignition power supply

AUTOMATIC GEARBOX - ZF4HP22 - 24
44-4 DESCRIPTION AND OPERATION
Description
General
The automatic gearbox is a four speed unit with electronic control of gear selection, shift quality and torque converter
lock-up. Selections on the selector lever assembly are transmitted to the gearbox by a selector cable. A gear position
switch on the gearbox transmits the gear selection to an Electronic Automatic Transmission (EAT) ECU, which
outputs the appropriate control signals to an electro-hydraulic valve block in the gearbox. A mode switch enables the
driver to change the control mode of the EAT ECU. The EAT ECU operates warning lamps in the instrument pack to
indicate the control mode and system status.
The gearbox features a pressure lubrication system and is cooled by pumping the lubricant through an oil cooler.
On NAS market vehicles from 03 model year, the ZF 4HP24 transmission unit is introduced for use with the 4.6 litre
V8 engine. This transmission is required to accomodate the increased power output of the larger engine. The ZF
4HP22 transmission remains in use on vehicles with Td5 and 4.0 litre V8 engines.
Both transmission units are of similar construction, with the ZF 4HP24 unit being 15 mm longer than the 4HP22 unit
to accomodate a larger fluid pump. The operation of both transmission units is the same.

AUTOMATIC GEARBOX - ZF4HP22 - 24
DESCRIPTION AND OPERATION 44-7
The gearbox consists of a torque converter housing, an intermediate plate, a gearbox housing and a rear extension
housing, bolted together in series. The rear of the gearbox is supported by a rubber mounting installed between a
mounting bracket on the gearbox and the LH chassis rail. A heat shield is installed on the mounting to protect it from
the exhaust.
Sectioned view of gearbox
1Lock-up clutch
2Impeller
3Turbine
4Forward drive clutch
5Reverse drive clutch
6Brake clutch
7Brake clutch
8Brake clutch
9Epicyclic gear set10Epicyclic gear set
11Clutch
12Brake clutch
13Output shaft
14Freewheel (one way clutch)
15Freewheel (one way clutch)
16Freewheel (one way clutch)
17Stator and one way clutch
Torque converter housing
The torque converter housing attaches the gearbox to the engine and contains the torque converter. Different torque
converter housings are used to accommodate the difference between the V8 and Td5 engine interfaces. The torque
converter is connected to the engine drive plate and transmits the drive from the engine to the gearbox input shaft.
When engaged, a hydraulic lock-up clutch in the torque converter prevents slippage, to give a direct drive from the
engine to the gearbox for improved driving response.
Intermediate plate
The intermediate plate supports the gearbox input shaft and provides the interface between the transmission fluid
pump and the lubrication circuit. The pump attaches to the front of the intermediate plate and is driven by the impeller
in the torque converter. The pump pressurises transmission fluid drawn from the sump on the gearbox housing. The
pressurised fluid then circulates through the torque converter and gearbox housing components for cooling,
lubrication and gear shift purposes. Ports around the outer periphery of the intermediate plate provide the inlet and
outlet connections to the fluid cooler and a pressure take-off point for servicing.

AUTOMATIC GEARBOX - ZF4HP22 - 24
44-10 DESCRIPTION AND OPERATION
The lock-up and brake clutches are operated by pressurised transmission fluid from the valve block in the sump. A
manual valve and four solenoid valves, also known as Motorised Valves (MV), control the supply of pressurised
transmission fluid from the valve block:
lThe manual valve controls the supply in P, R, N and D.
lSolenoid valves MV 1 and MV 2 control the supplies that operate the brake clutches for shift control.
lSolenoid valve MV 3 controls the supply that operates the lock-up clutch.
lSolenoid valve MV 4 modulates the pressure of the supplies to the brake clutches, to control shift quality.
Operation of the manual valve is controlled by the selector lever assembly. In the gearbox, a selector shaft engages
with the manual valve. The selector shaft is connected to the selector lever assembly via the selector cable and a
selector lever on the left side of the gearbox. The selector shaft also operates a mechanism that locks the output shaft
when P is selected.
Operation of the solenoid valves is controlled by the EAT ECU.
An output shaft speed sensor in the gearbox housing outputs a signal to the EAT ECU. The EAT ECU compares
output shaft speed with engine speed to determine the engaged gear, and output shaft speed with vehicle speed to
confirm the range selected on the transfer box.
A bayonet lock electrical connector in the gearbox casing, to the rear of the selector lever, connects the solenoid
valves and the output shaft speed sensor to the vehicle wiring.
A pressed steel sump encloses the valve block and collects transmission fluid draining from the gearbox housing. A
suction pipe and filter on the underside of the valve block connect to the inlet side of the fluid pump. A magnet is
installed in the sump to collect any magnetic particles that may be present. A level plug and a drain plug are installed
in the sump for servicing.
Rear extension housing
The rear extension housing provides the interface between the gearbox housing and the transfer box. A splined
extension shaft, secured to the gearbox output shaft by a bolt, transmits the drive from the gearbox to the transfer
box. A seal in the rear of the housing prevents leakage past the extension shaft. A breather pipe, attached to the left
side of the rear extension housing, ventilates the interior of the gearbox and rear extension housings to atmosphere.
The open end of the breather pipe is located in the engine compartment at the right front corner of the engine sump
on gearboxes fitted to early vehicles and is clipped to the top of the gearbox on later vehicles.
Gearbox power flows
The following Figures show the power flow through the gearbox for each forward gear when D is selected, and for
reverse. The key to the Item numbers on the Figures, and in parenthesis in the accompanying text, can be found on
the 'Sectioned view of gearbox' Figure, above.
1st Gear (D selected)
Clutches (4) and (11) are engaged. The front planet gear carrier of gear set (9) locks against the gearbox housing
through freewheel (15) when the engine powers the vehicle, and freewheels when the vehicle is coasting. Gear set
(10) rotates as a solid unit with the front planet gear carrier. In 1st gear hold brake clutch (8) is applied to provide
overrun braking.

AUTOMATIC GEARBOX - ZF4HP22 - 24
DESCRIPTION AND OPERATION 44-13
Oil cooler
1Inlet connection
2Fixing bracket
3Outlet connection4Fixing bracket
5Temperature sensor
Transmission fluid from the gearbox is circulated through a cooler attached to the front of the radiator. Quick release
connectors on the transmission fluid lines attach to connections on each end tank of the cooler. A temperature sensor
on the RH end tank provides the instrument pack with an input of transmission fluid temperature. If the temperature
exceeds a preset limit, the instrument pack illuminates the transmission temperature warning lamp. The warning lamp
remains illuminated until the temperature of the fluid returns within limits.
EAT ECU
The EAT ECU operates the solenoid valves in the gearbox to provide automatic control of gear shifts and torque
converter lock-up. The EAT ECU is attached to a protective bracket which is secured to the cabin floor below the LH
front seat. A 55 pin connector links the EAT ECU to the vehicle wiring.
Software in the EAT ECU monitors hard wired inputs and exchanges information with the ECM on a Controller Area
Network (CAN) bus to determine gear shift and torque converter lock-up requirements. Resultant control signals are
then output to the gearbox solenoid valves.