1999 LAND ROVER DISCOVERY sensor

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.

AUTOMATIC GEARBOX - ZF4HP22 - 24
44-14 DESCRIPTION AND OPERATION
EAT ECU connector
EAT ECU connector pin details
Pin No. Description Inputs/Outputs
1 to 4 Not used -
5 Pressure regulator solenoid valve (MV 4) Output
6 Power earth -
7 Not used -
8 Gear position switch, X contacts Input
9 Gear position switch, Z contacts Input
10 to 12 Not used -
13 Transmission high/low switch Input
14 Gearbox output shaft speed sensor, negative Input
15 Gearbox output shaft speed sensor cable screen -
16 CAN, high Input/Output
17 to 24 Not used -
25 Sport mode warning lamp Output
26 Battery power supply Input
27 Not used -
28 Electronics earth -
29 Not used -
30 Shift control solenoid valve (MV 1) Output
31 Diagnostics, K line Input/Output
32 Converter lock-up solenoid valve (MV 3) Output
33 Shift control solenoid valve (MV 2) Output
34 Not used -
35 Not used -
36 Gear position switch, W contacts Input
37 Gear position switch, Y contacts Input
38 to 41 Not used -
42 Gearbox output shaft speed sensor, positive Input
43 Not used -
44 CAN, low Input/Output
45 Mode switch Input
46 to 50 Not used -
51 Manual mode warning lamp Output
52 Not used -
53 Solenoid valves power supply Output
54 Ignition power supply Input
55 Not used -

AUTOMATIC GEARBOX - ZF4HP22 - 24
44-18 DESCRIPTION AND OPERATION
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.
After the detection of a fault, the effects remain active for the remainder of the drive cycle. In subsequent drive cycles,
as soon as the EAT ECU diagnoses the fault is no longer present, it resumes normal control of the gearbox. The
conditions required to diagnose that the fault is no longer present depend on the fault. Some faults require the engine
to be started, others require only that the ignition is switched on.
After a fault has not recurred for forty warm-up cycles, the fault is deleted from the EAT ECU memory. Only five
different faults can be stored in the memory at any one time. If a further fault occurs, the fault with the lowest priority
will be replaced by the new fault.
Mechanical limp home
In the mechanical limp home mode, gear engagement is controlled by the manual valve. The gearbox is fixed in 4th
gear if the fault occurs while the vehicle is moving, or 3rd gear if the fault occurs while the vehicle is stationary. 3rd
gear is also engaged if a vehicle is brought to a stop and the selector lever is moved out of, and back into, D. Neutral
and reverse gear are also available.

AUTOMATIC GEARBOX - ZF4HP22 - 24
44-28 REPAIRS
15.Remove handbrake drum retaining screw and
remove brake drum.
16.Remove 4 bolts from handbrake back plate,
release back plate and tie aside.
17. Models fitted with high/low shift interlock
solenoid: Release interlock solenoid multiplug
and disconnect multiplug from main harness.
18. Models fitted with high/low shift interlock
solenoid: Remove sleeve retaining rings and
remove sleeve from high/low selector cable.
19. If fitted Remove and discard clevis pin
securing differential lock selector cable to
transfer gearbox.20. If fitted Loosen locknuts securing differential
lock selector cable to differential lock selector
cable abutment bracket.
21. If fitted Release and remove differential lock
selector cable from differential lock selector
cable abutment bracket.
22.Remove clevis pin securing high/low ratio
selector cable to selector lever, remove 'C' clip
and remove outer cable from abutment
bracket.
23. Up to 03 Model Year - If fitted: Disconnect
from differential lock warning lamp switch and
multiplugs from high/low ratio switch and
neutral sensor.

AUTOMATIC GEARBOX - ZF4HP22 - 24
REPAIRS 44-31
40.Fit suitable strap to retain torque converter.
Refit
1.Clean gearbox to engine mating faces.
2.Remove torque converter retaining strap.
3.With assistance position gearbox to engine.
4.Fit but do not tighten six bolts securing gearbox
housing to engine.
5.Connect multiplug to gearbox and tighten
locking ring.
6.Connect multiplug to inhibitor switch.
7. If fitted: Connect and adjust differential lock
selector cable.

+ TRANSFER BOX - LT230SE,
ADJUSTMENTS, Cable - selector -
differential lock - adjust.
8.Position selector lever to inhibitor switch and
tighten nut to 25 Nm (18 lbf.ft).
9.Position selector cable to gearbox and secure
with 'C' clip.
10.Clean oil pipe unions and fit new 'O' rings.
11.Position and tighten pipe unions to gearbox.
12.Position and tighten oil cooler pipe clamps.
13.Position and tighten oil cooler pipe clips to
engine sump and alternator bracket.
14.Position engine RH and LH rear mountings
and tighten bolts to 85 Nm (63 lbf.ft) and nuts to
85 Nm (63 lbf.ft).
15.Secure gearbox breather pipes to bulkhead
clip.
16. Up to 03 Model Year - If fitted: Connect 2
Lucars to differential lock warning lamp switch
and multiplugs to high/low ratio switch and
neutral sensor.
17. 03 Model Year onwards - If fitted: Connect
differential lock warning lamp switch multiplugs
to main harness.
18.Position cable tie and multiplug to transfer box
bracket.
19.Connect high/low ratio selector cable to
selector lever and secure with clevis pin. 20.Position high/low ratio selector cable to
abutment bracket and secure with 'C' clip.
21. Models fitted with high/low shift interlock
solenoid: Position interlock solenoid harness
to high/low shift cable, fit sleeve around cable
and harness.
22. Models fitted with high/low shift interlock
solenoid: Connect solenoid multiplug to main
harness and secure multiplug to bracket.
23.Position handbrake backplate and tighten bolts
to 75 Nm (55 lbf.ft).
24.Fit hand brake drum and tighten screw.
25.Remove bolts securing tool LRT-99-008A to
gearbox.
26.Rotate engine to align torque converter, fit new
bolts and tighten to 50 Nm (37 lbf.ft).
27.Fit rear propeller shaft.

+ PROPELLER SHAFTS, REPAIRS,
Propeller shaft - rear.
28.Fit front propeller shaft.

+ PROPELLER SHAFTS, REPAIRS,
Propeller shaft - front.
29.Fill transfer gearbox with oil.

+ MAINTENANCE, PROCEDURES,
Transfer box.
30.Fill automatic gearbox with oil.

+ MAINTENANCE, PROCEDURES,
Automatic gearbox.
31.Position intermediate silencer and secure to
mounting rubbers.
32.Clean silencer and tail pipe mating faces.
33.Position new gasket to tail pipe and tighten
nuts to 25 Nm (18 lbf.ft).
34.Fit exhaust front pipe.

+ MANIFOLDS AND EXHAUST
SYSTEMS - Td5, REPAIRS, Pipe - front.
35.Fit bolt securing closing plate to gearbox
housing and tighten to 7 Nm (5.2 lbf.ft).
36.Fit upper bolts securing gearbox housing to
engine and tighten to 50 Nm (37 lbf.ft).
37.Fit starter motor.

+ CHARGING AND STARTING,
REPAIRS, Starter motor - diesel.
38.Tighten remaining gearbox housing to engine
bolts to 50 Nm (37 lbf.ft).
39.Connect battery earth lead.
40.Fit battery cover and secure with fixings.
41.Check and adjust selector cable.

+ AUTOMATIC GEARBOX - ZF4HP22
- 24, ADJUSTMENTS, Cable - selector.

AUTOMATIC GEARBOX - ZF4HP22 - 24
REPAIRS 44-33
16. Models fitted with high/low shift interlock
solenoid: Release interlock solenoid multiplug
and disconnect multiplug from main harness.
17. Models fitted with high/low shift interlock
solenoid: Remove sleeve retaining rings and
remove sleeve from high/low selector cable.
18. If fitted Remove and discard clevis pin
securing differential lock selector cable to
transfer gearbox.
19. If fitted Loosen locknuts securing differential
lock selector cable to differential lock selector
cable abutment bracket.
20. If fitted Release and remove differential lock
selector cable from differential lock selector
cable abutment bracket.
21.Remove clevis pin securing high/low ratio
selector cable to selector lever, remove 'C' clip
and remove outer cable from abutment bracket22. Up to 03 Model Year - If fitted: Disconnect 2
Lucars from differential lock switch and
multiplugs from high/low ratio switch and
neutral sensor.
23. 03 Model Year onwards - If fitted: Release
and disconnect both differential lock warning
lamp switch multiplugs from main harness.
24.Release transfer and automatic gearbox
breather pipes from clip at rear of cylinder
block.

AUTOMATIC GEARBOX - ZF4HP22 - 24
REPAIRS 44-35
32.Remove 'C' clip securing selector cable to
gearbox bracket.
33.Remove nut securing selector lever to inhibitor
switch and release lever.
34.Disconnect multiplug from inhibitor switch.
35.Loosen gearbox multiplug locking ring and
disconnect plug.
36.Lower gearbox sufficiently to access bell
housing bolts, take care not to trap any pipes or
cables when lowering gearbox.
37.Remove 14 bolts securing gearbox to engine.
38.With assistance remove gearbox from engine.39.Fit suitable strap to retain torque converter.
Refit
1.Clean gearbox to engine mating faces.
2.Remove torque converter retaining strap.
3.With assistance position gearbox to engine.
4.Fit gearbox bell housing bolts and tighten to 46
Nm (34 lbf.ft)..
5.Connect multiplug to gearbox and tighten
locking ring.
6.Connect inhibitor switch multiplug.
7. If fitted: Connect and adjust differential lock
selector cable.

+ TRANSFER BOX - LT230SE,
ADJUSTMENTS, Cable - selector -
differential lock - adjust.
8.Position selector lever to inhibitor switch and
tighten nut to 25 Nm (18 lbf.ft).
9.Position selector cable to gearbox and secure
with 'C' clip.
10.Clean oil pipe unions and fit new 'O' rings.
11.Position and tighten pipe unions to gearbox.
12.Position and tighten oil cooler pipe clamps.
13.Position and tighten oil cooler pipe clip to
engine sump.
14.Position engine RH and LH rear mountings
and tighten bolts to 85 Nm (63 lbf.ft) and nuts to
85 Nm (63 lbf.ft).
15.Secure gearbox breather pipes to bulkhead
clip.
16. Up to 03 Model Year - If fitted: Connect 2
Lucars to differential lock warning lamp switch
and multiplugs to high/low ratio switch and
neutral sensor.
17. 03 Model Year onwards - If fitted: Connect
differential lock warning lamp switch multiplugs
to main harness.
18.Position cable tie and multiplug to transfer
gearbox bracket.
19.Connect high/low ratio selector cable to
selector lever and secure with clevis pin.
20.Position high/low ratio selector cable to
abutment bracket and secure with 'C' clip.

AUTOMATIC GEARBOX - ZF4HP22 - 24
REPAIRS 44-47
Refit
1.Clean park lock components.
2.Lubricate and fit new 'O' ring to output shaft.
3.Position park lock gear on the output shaft.
4. Td5 models: Fit the spacer.
CAUTION: Ensure that spacer is fitted on
output shaft - Tdi Models only. If spacer is
omitted, park gear and speed sensor may
move out of position.
5.Position pivot pin, spring and ratchet.
6.Position parking pawl guide and guide plate,
tighten Torx screw to 10 Nm (8 lbf.ft).
7.Clean extension housing and gearbox case.
8.Position new gasket to gearbox case.
9.Position extension housing and tighten bolts to
25 Nm (18 lbf.ft).
10.Fit transfer gearbox.

+ TRANSFER BOX - LT230SE,
REPAIRS, Transfer box - Diesel.

+ TRANSFER BOX - LT230SE,
REPAIRS, Transfer box - V8.
11.Fill automatic gearbox with oil.

+ MAINTENANCE, PROCEDURES,
Automatic gearbox.
Gasket - oil sump
$% 44.24.05
Remove
1.Raise vehicle on ramp.
2.Drain automatic gearbox oil.

+ MAINTENANCE, PROCEDURES,
Automatic gearbox.
3.Remove 6 bolts and spacers securing oil sump
to gearbox, remove sump and discard gasket.
Refit
1.Clean oil sump and mating face.
2.Fit new gasket to oil sump, position sump to
gearbox.
3.Position spacers and tighten bolts to 8 Nm (6
lbf. ft).
4.Fill automatic gearbox with oil.

+ MAINTENANCE, PROCEDURES,
Automatic gearbox.
5.Lower vehicle.