automatic transmission fluid LAND ROVER DISCOVERY 2002 Workshop Manual

CONTENTS
CONTENTS 13
Cooler - fluid - V8 ........................................................................................................................... 44-46
Valve body assembly ..................................................................................................................... 44-47
Seal - valve body ........................................................................................................................... 44-49
Pressure regulator ......................................................................................................................... 44-50
Lock-up solenoid valve (MV 3) ....................................................................................................... 44-51
Solenoids - shift control valves (MV 1 & 2) .................................................................................... 44-51
Harness - solenoid valves .............................................................................................................. 44-52
Electronic control unit - automatic transmission .............................................................................. 44-53
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
Flexible coupling ............................................................................................................................ 47-6
OVERHAUL
Propeller shaft ................................................................................................................................. 47-7
REAR AXLE .............................................................................................. 51-1
DESCRIPTION AND OPERATION
Rear axle component layout ........................................................................................................... 51-1
Description ...................................................................................................................................... 51-2
REPAIRS
Differential - assembly .................................................................................................................... 51-5
Seal - differential pinion ................................................................................................................. 51-7
OVERHAUL
Differential assembly ...................................................................................................................... 51-9
FRONT AXLE............................................................................................ 54-1
DESCRIPTION AND OPERATION
Front axle component layout........................................................................................................... 54-1
Description ...................................................................................................................................... 54-2
REPAIRS
Differential - assembly .................................................................................................................... 54-5
Seal - differential pinion ................................................................................................................ 54-7
Seal - oil - front axle casing ........................................................................................................... 54-9
Constant velocity joint - drive shaft ................................................................................................ 54-11
STEERING ................................................................................................ 57-1
DESCRIPTION AND OPERATION

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 switch
5Oil 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.
Selector lever assembly

AUTOMATIC GEARBOX - ZF4HP22 - 24
44-8 DESCRIPTION AND OPERATION
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.
Gearbox housing
The gearbox housing contains two epicyclic gear sets on input and output shafts. Hydraulic brake clutches on the
shafts, control which elements of the gear sets are engaged, and their direction of rotation, to produce the P and N
selections, four forward gear ratios and one reverse gear ratio.
Gear ratios
Gear Ratio
1st 2.480 : 1
2nd 1.480 : 1
3rd 1.000 : 1
4th 0.728 : 1
Reverse 2.086 : 1

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 connection
4Fixing 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.

AUTOMATIC GEARBOX - ZF4HP22 - 24
REPAIRS 44-35
Refit
1.Clean oil seal running surfaces.
2.Lubricate oil seal with transmission fluid.
3.Fit new seal into converter housing using tool
LRT-44-001.
4.Fit tool LRT-44-010 to torque converter.
5.Align oil pump drive and fit torque converter to
gearbox.
6.Remove tool LRT-44-010 from torque
converter.
7.Fit torque converter retaining strap.
8.Fit automatic gearbox.
l

+ AUTOMATIC GEARBOX -
ZF4HP22 - 24, REPAIRS, Gearbox -
convertor and transfer gearbox - Diesel.
l

+ AUTOMATIC GEARBOX -
ZF4HP22 - 24, REPAIRS, Gearbox -
convertor and transfer gearbox - V8.
Housing - torque converter
$% 44.17.01
Remove
1.Remove torque converter oil seal.

+ AUTOMATIC GEARBOX - ZF4HP22
- 24, REPAIRS, Torque converter and oil
seal.
2.Remove 18 bolts and plain washers securing
torque converter and intermediate plate to
gearbox casing. Note the position of the 4 bolts
that have sealant applied to the bolt threads
and 6 bolts, (outer ring), which are shorter.
3.Hold input shaft in position and carefully
remove the converter housing and intermediate
plate from gearbox casing.
4.Note the position of the Torrington race on the
forward clutch hub and the thrust washer which
will stay attached to the intermediate plate by
fluid adhesion.
5.Remove and discard intermediate plate gasket.
6.Remove thrust washer from intermediate plate.
7.Separate converter housing from intermediate
plate.
M44 1343
M44 1345

AUTOMATIC GEARBOX - ZF4HP22 - 24
REPAIRS 44-39
7.Note position and remove pump locating dowel.
8.Remove and discard 'O' ring from pump
housing.
9.Remove 6 bolts securing converter housing to
intermediate plate, and release intermediate
plate from converter housing.Refit
1.Clean intermediate plate and mating faces with
a lint free cloth.
2.Position intermediate plate to converter
housing, fit bolts and tighten evenly to 46 Nm
(34 lbf.ft)
3.Fit new sealing washers to M14 Allen plugs, fit
plugs and tighten to 40 Nm (30 lbf.ft).
4.Fit new sealing washers to M20 plugs, fit plugs
and tighten to 50 Nm (37 lbf.ft).
5.Fit oil cooler adaptors and tighten to 42 Nm (30
lbf.ft)
6.Clean pump housing and mating face on
intermediate plate with lint free cloth.
7.Lubricate new 'O' ring with transmission fluid
and fit to pump housing.
8.Position pump locating dowel into intermediate
plate.
9.Align pump to dowel and position in
intermediate plate.
10.Fit bolts and tighten in a diagonal sequence to
10 Nm (7 lbf.ft)
11.Position LRT-44-003/1 into pump and check
that the pump rotors turn freely.
12.Fit intermediate plate gasket.

+ AUTOMATIC GEARBOX - ZF4HP22
- 24, REPAIRS, Gasket - intermediate plate.
M44 1341
M44 1357
M44 1342
LRT-44-003/1

AUTOMATIC GEARBOX - ZF4HP22 - 24
44-40 REPAIRS
Pump - fluid
$% 44.32.01
Remove
1.Remove intermediate plate gasket.

+ AUTOMATIC GEARBOX - ZF4HP22
- 24, REPAIRS, Gasket - intermediate plate.
2.Remove 8 bolts securing fluid pump to
intermediate plate and carefully remove pump
from intermediate plate.
3.Note position and remove pump locating dowel.
4.Remove and discard 'O' ring from pump
housing.
Refit
1.Clean pump housing and mating face on
intermediate plate with lint free cloth.
2.Lubricate new 'O' ring with transmission fluid
and fit to pump housing.
3.Position pump locating dowel into intermediate
plate.
4.Align fluid pump to dowel and position in
intermediate plate.5.Fit bolts and tighten in a diagonal sequence to
10 Nm (7 lbf.ft)
6.Position LRT-44-003/1 into pump and check
that the pump rotors turn freely.
7.Fit intermediate plate gasket.

+ AUTOMATIC GEARBOX - ZF4HP22
- 24, REPAIRS, Gasket - intermediate plate.
M44 1336
M44 1341
M44 1342
LRT-44-003/1