sensor LAND ROVER DISCOVERY 1999 Workshop Manual

TRANSFER BOX - LT230SE
41-30 REPAIRS
12. If fitted: Release and remove clevis pin
securing differential lock selector cable to
transfer gearbox.
13. If fitted: Loosen locknuts securing differential
lock selector cable to differential lock selector
cable abutment bracket.
14. If fitted: Release and remove differential lock
selector cable from differential lock selector
cable abutment bracket.
15.Remove clevis pin and 'C' clip securing high/
low ratio selector cable to selector lever and
release cable from abutment bracket.
16.Remove 2 cable ties securing cable to fuel
pipes. 17. If fitted: Disconnect 2 Lucars from oil
temperature sensor and disconnect reverse
lamp switch multiplug.
18.Remove banjo bolt securing breather pipe and
discard washers.
19. Up to 03 Model Year - if fitted: Disconnect 2
Lucars from differential lock switch and
multiplugs from high/low ratio switch and
neutral sensor.
20.Disconnect multiplug from reverse light switch.

TRANSFER BOX - LT230SE
41-32 REPAIRS
Refit
1.Fit new input shaft oil seal.

+ TRANSFER BOX - LT230SE,
REPAIRS, Oil seal - input shaft.
2.Clean transfer box to gearbox mating faces.
3.Raise transfer box on jack and align to guide
studs LRT-41-009.
4.Clean transfer box to gearbox bolt threads.
5.Apply sealant, Part No. STC 50552 to bolt and
stud threads.
6.Fit and lightly tighten 2 bolts and nut securing
transfer box to gearbox. If new stud is to be
fitted, apply sealant, Part No. STC 50552 to
stud threads and tighten to 45 Nm (33 lbf.ft).
7.Remove guide studs, fit and lightly tighten 3
bolts.
8.Tighten bolts and nut by diagonal selection to
45 Nm (33 lbf.ft.
9.Position gearbox RH mounting and tighten
bolts to 85 Nm (63 lbf.ft).
10.Tighten gearbox RH mounting nut to 48 Nm
(35 lbf.ft).
11.Fit nut to LH mounting and tighten to 48 Nm (35
lbf.ft).
12.Remove 4 bolts securing support plate to
gearbox jack.
13.Remove 4 bolts securing support plate LRT-99-
010 to transfer box and remove plate.
14.Clean threads of bottom plate bolts.
15.Apply sealant, Part No. STC 50552 to threads
of 4 bottom plate bolts.
16.Fit 4 bolts securing bottom plate and tighten to
25 Nm (18 lbf.ft).
17.Using new washers position breather pipe and
tighten banjo bolt.
18.Connect multiplug to transfer box neutral switch
and secure harness.
19. Up to 03 Model Year - if fitted : Connect
Lucars to differential lock switch and multiplugs
to high/low ratio switch and neutral sensor.
20. 03 Model Year onwards - if fitted: Connect
differential lock warning lamp multiplugs,
secure harness.
21.Connect multiplug to reverse lamp switch.
22. If fitted: Connect Lucars to oil temperature
switch.
23.Position high/low ratio selector cable and
secure with 'C' clip and clevis pin.
24. If fitted: Position differential lock selector cable
to differential lock selector cable abutment
bracket and tighten locknuts sufficiently to
retain cable.
25. If fitted: Fit differential lock selector cable to
transfer gearbox and secure with clevis pin.
26. If fitted: Adjust differential lock selector cable.

+ TRANSFER BOX - LT230SE,
ADJUSTMENTS, Cable - selector -
differential lock - adjust.27. Models fitted with high/low shift interlock
solenoid: Position interlock solenoid harness
to high/low shift cable, fit sleeve around cable
and harness; secure sleeve.
28. Models fitted with high/low shift interlock
solenoid: Connect solenoid multiplug to main
harness and secure multiplug to bracket.
29.Secure cable to fuel pipes with new cable ties.
30.Clean handbrake back plate and mating face.
31.Position handbrake back plate, fit bolts and
tighten to 75 Nm (55 lbf.ft).
32.Clean handbrake drum.
33.Fit handbrake drum and tighten retaining
screw.
34.Fit front propeller shaft.

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

+ PROPELLER SHAFTS, REPAIRS,
Propeller shaft - rear.
36.Clean exhaust silencer and tail pipe mating
faces.
37.Position silencer and secure on mountings,
using a new gasket align to tail pipe, fit nuts
and tighten to 25 Nm (18 lbf.ft).
38.Position rear cross member, fit bolts and
tighten to 26 Nm (19 lbf.ft).
39.Refill transfer box with oil.

+ MAINTENANCE, PROCEDURES,
Transfer box.
40.Fit front exhaust pipe.

+ MANIFOLDS AND EXHAUST
SYSTEMS - V8, REPAIRS, Front pipe.

TRANSFER BOX - LT230SE
REPAIRS 41-41
Sensor - neutral
$% 41.20.64
Remove
1.Raise vehicle on ramp.
2.Disconnect multiplug from neutral sensor.
3.Remove sensor and discard sealing washer.
Refit
1.Clean sensor threads.
2.Fit new washer and apply sealant, Part No.
STC 50552 to threads of sensor.
3.Fit and tighten sensor to 25 Nm (18 lbf.ft).
4.Lower vehicle on ramp.
Sensor - oil temperature - If fitted
$% 41.20.80
Remove
1.Lower vehicle.
2.Disconnect 2 Lucar connectors from oil
temperature sensor.
3.Remove oil temperature sensor and discard
sealing washer.
Refit
1.Clean sensor and mating face on transfer box.
2.Fit new sealing washer, position oil
temperature sensor and tighten to 25 Nm (18
lbf.ft).
3.Connect Lucar connectors to oil temperature
sensor.
4.Lower vehicle.

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
DESCRIPTION AND OPERATION 44-9
Valve block
1Valve block
2Pressure regulating solenoid valve (MV 4)
3Shift control solenoid valve (MV 2)
4Shift control solenoid valve (MV 1)
5Lock-up solenoid valve (MV 3)
6Output shaft speed sensor
7Bolt
8Sensor retaining clip9Manual valve
10'O' ring
11Filter
12'O' ring
13Suction pipe
14Bolt
15Bolt
16Washer

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.

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.