lock LAND ROVER DISCOVERY 2002 Workshop Manual

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
DESCRIPTION AND OPERATION 44-19
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.
Fault effects and warning indications
Fault code,
OBD II
(TestBook)Fault description Effect Warning lamp
illumination
MIL Sport/
Manual
P0705
(14, 23)* Gear position switch,
incorrect outputsMaintains current gear in low range, limp home
mode in high range. Shift pressure to maximum,
harsh gear shifts/engagement.On On
P0721
(21)* Downshift safety
monitor prevented
downshift which would
have caused engine
overspeedMaintains current gear in low range, limp home
mode in high range. Shift pressure to maximum,
harsh gear shifts/engagement.On On
P0722
(22)* Torque converter
slippingMaintains current gear in low range, limp home
mode in high range. Shift pressure to maximum,
harsh gear shifts/engagement.On On
P0731
(29)* Ratio monitoring,
implausible 1st gear ratioNo apparent effect On On
P0732
(30)* Ratio monitoring,
implausible 2nd gear
ratioNo apparent effect On Off
P0733
(31)* Ratio monitoring,
implausible 3rd gear
ratioNo apparent effect On Off
P0734
(32)* Ratio monitoring,
implausible 4th gear ratioNo apparent effect On Off
P0741
(5)* Torque converter lock-
up clutch faultMay affect driveability. On Off
P0743
(7, 25)* Torque converter lock-
up solenoid (MV 3), open
or short circuitLimp home mode in low and high ranges. Shift
pressure to maximum, harsh gear shifts/
engagement.On On
P0748
(10, 28)* Pressure regulating
solenoid (MV 4), open or
short circuitLimp home mode in low and high ranges. Shift
pressure to maximum, harsh gear shifts/
engagement.On On
P0753
(8, 26)* Shift solenoid (MV 1),
open or short circuitLimp home mode in low and high ranges. Shift
pressure to maximum, harsh gear shifts/
engagement.On On
P0758
(9, 27)* Shift solenoid (MV 2),
open or short circuitLimp home mode in low and high ranges. Shift
pressure to maximum, harsh gear shifts/
engagement.On On
P1562
(24)* Battery supply below
9V while engine runningMaintains current gear in low range, limp home
mode in range. Shift pressure to maximum, harsh
gear shifts/engagement.Off On

AUTOMATIC GEARBOX - ZF4HP22 - 24
REPAIRS 44-23
REPAIRS
Cable and lever assembly - selector
$% 44.15.08
Remove
1.Remove centre console.

+ INTERIOR TRIM COMPONENTS,
REPAIRS, Console - centre - automatic
models.
2.Raise vehicle on ramp.
3.Loosen selector cable trunnion nut.
4.Remove 'C' clip and release selector cable
from gearbox bracket.
5.Lower vehicle on ramp.
6.Remove sound deadener pad. 7.Remove 3 bolts securing selector lever bracket
to tunnel, remove selector lever.
8.Remove 'C' clip securing outer cable to
selector lever bracket.
9.Remove locking ring securing inner cable to
selector lever.
10.Release inner cable from selector lever,
release cable from grommet and remove cable
from selector lever bracket.
Refit
1.Position cable through grommet, align to
bracket and secure with 'C' clip.
2.Fit inner cable to selector lever and secure with
locking ring.
3.Feed selector cable through tunnel, align
bracket, fit and tighten bolts.
4.Fit sound deadener pad.
5.Fit centre console.

+ INTERIOR TRIM COMPONENTS,
REPAIRS, Console - centre - automatic
models.
6.Position selector cable through trunnion and
gearbox bracket, secure with 'C' clip.
7.Adjust selector cable.

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

AUTOMATIC GEARBOX - ZF4HP22 - 24
44-24 REPAIRS
Selector indicator
$% 44.15.10
Remove
1.Remove knob from gear lever.
2.Release selector panel from centre console.
3.Disconnect multiplug from selector panel and
remove panel.
Refit
1.Position selector panel and connect multiplug.
2.Secure selector panel to console.
3.Fit gear lever knob.
Switch - starter inhibitor
$% 44.15.19
Remove
1. Diesel models: Remove exhaust front pipe.

+ MANIFOLDS AND EXHAUST
SYSTEMS - Td5, REPAIRS, Pipe - front.
2.Move the selector lever to position 'P'.
3.Remove nut securing selector lever to gearbox
selector shaft and release lever.
4.Remove 2 bolts securing inhibitor switch to
gearbox.
5.Release multiplug from gearbox bracket.
6.Release inhibitor switch from selector shaft.
7.Disconnect switch multiplug and remove
switch.
Refit
1.Ensure 'P' is selected by rotating selector shaft
fully clockwise.
2.Engage 'N' by rotating selector shaft 2 detents
anti-clockwise.
3.Position inhibitor switch to selector shaft,
connect multiplug and secure multiplug to
gearbox bracket.
4.Engage switch to selector shaft, and fit but do
not tighten retaining bolts.

AUTOMATIC GEARBOX - ZF4HP22 - 24
REPAIRS 44-27
11.Drain transfer gearbox oil.

+ MAINTENANCE, PROCEDURES,
Transfer box.
12.Remove front propeller shaft

+ PROPELLER SHAFTS, REPAIRS,
Propeller shaft - front.
13.Remove rear propeller shaft

+ PROPELLER SHAFTS, REPAIRS,
Propeller shaft - rear.
14.Remove and discard 3 bolts securing torque
converter to drive plate.
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.Remove clip securing high/low ratio selector
cable to transfer gearbox lever, remove 'C' clip
and remove outer cable from gearbox.
18.Disconnect 2 Lucars from differential lock
switch and multiplugs from high/low ratio switch
and neutral sensor.
19.Remove cable tie and multi plug from bracket
to transfer box.

AUTOMATIC GEARBOX - ZF4HP22 - 24
44-28 REPAIRS
20.Release transfer and automatic gearbox
breather pipes from clip at rear of cylinder
block.
21.Position gearbox support jack and secure tool
LRT-99-008A to support plate on jack.
22.Position a second support jack under engine
using a block between engine sump and jack
to prevent damage to sump.
23.Remove 4 bolts and nut, remove engine LH
rear mounting. 24.Remove 4 bolts and nut, remove engine RH
rear mounting.
25.Remove 2 bolts securing gearbox oil cooler
pipe clips to engine sump and alternator
mounting bracket.
26.Remove bolt and 2 nuts securing clamps to oil
cooler pipes and remove clamps.

AUTOMATIC GEARBOX - ZF4HP22 - 24
REPAIRS 44-29
27.Loosen gearbox oil cooler pipe unions, release
pipes from gearbox and discard 'O' rings.
CAUTION: Always fit plugs to open
connections to prevent contamination.
28.Remove 'C' clip securing selector cable to
gearbox bracket.
29.Remove nut securing selector lever to inhibitor
switch and release lever.
30.Disconnect multiplug from inhibitor switch.
31.Loosen gearbox multi plug locking ring and
disconnect plug. 32.Remove 6 remaining gearbox housing bolts.
33.With assistance remove automatic gearbox
from engine.
34.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.Position selector lever to inhibitor switch and
tighten nut to 25 Nm (18 lbf.ft).
8.Position selector cable to gearbox and secure
with 'C' clip.
9.Clean oil pipe unions and fit new 'O' rings.
10.Position and tighten pipe unions to gearbox.
11.Position and tighten oil cooler pipe clamps.
12.Position and tighten oil cooler pipe clips to
engine sump and alternator bracket.
13.Position engine RH and LH rear mountings
and tighten bolts to 85 Nm (63 lbf.ft) and nuts to
85 Nm (63 lbf.ft).

AUTOMATIC GEARBOX - ZF4HP22 - 24
44-30 REPAIRS
14.Secure gearbox breather pipes to bulkhead
clip.
15.Connect multiplugs to high/low ratio switch and
neutral sensor. Connect Lucars to differential
lock switch.
16.Position cable tie and multi plug to transfer box
bracket.
17.Connect high/low ratio cable to transfer box
and secure with retaining clips.
18.Position hand brake back plate and tighten
bolts to 75 Nm (55 lbf.ft).
19.Fit hand brake drum and tighten screw.
20.Remove bolts securing tool LRT-99-008A to
gearbox.
21.Rotate engine to align torque converter, fit new
bolts and tighten to 50 Nm (37 lbf.ft).
22.Fit rear propeller shaft.

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

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

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

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

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

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

+ AUTOMATIC GEARBOX - ZF4HP22
- 24, ADJUSTMENTS, Cable - selector.
Gearbox - convertor and transfer
gearbox - V8
$% 44.20.04.99
Remove
1.Release fixings and remove battery cover.
2.Disconnect battery earth lead.
3.Raise vehicle on a ramp.
4.Remove 8 bolts securing centre cross member
and remove cross member.
5.Remove exhaust front pipe.

+ MANIFOLDS AND EXHAUST
SYSTEMS - V8, REPAIRS, Front pipe.
6.Remove 3 nuts securing intermediate silencer
to tail pipe.
7.Release and remove silencer from rubber
mountings.
8.Drain automatic gearbox oil.

+ MAINTENANCE, PROCEDURES,
Automatic gearbox.
9.Drain transfer gearbox oil.

+ MAINTENANCE, PROCEDURES,
Transfer box.
10.Remove front propeller shaft

+ PROPELLER SHAFTS, REPAIRS,
Propeller shaft - front.

AUTOMATIC GEARBOX - ZF4HP22 - 24
REPAIRS 44-31
11.Remove rear propeller shaft

+ PROPELLER SHAFTS, REPAIRS,
Propeller shaft - rear.
12.Remove plug from torque converter housing to
access torque converter bolts.
13.Remove and discard 4 bolts securing torque
converter to drive plate.
14.Remove hand brake drum retaining screw and
remove brake drum.
15.Remove 4 bolts from hand brake back plate,
release back plate and tie aside. 16.Remove retaining clip securing high/low ratio
selector cable to transfer gearbox lever,
remove 'C' clip and remove outer cable from
gearbox.
17.Disconnect 2 Lucars from differential lock
switch and multiplugs from high/low ratio switch
and neutral sensor.
18.Remove cable tie and multiplug from bracket
on transfer gearbox.
19.Release transfer and automatic gearbox
breather pipes from clip at rear of cylinder
block.

AUTOMATIC GEARBOX - ZF4HP22 - 24
44-32 REPAIRS
20.Position gearbox support jack and secure tool
LRT-99-008A to support plate on jack.
21.Position a second support jack under engine
using a block between engine sump and jack to
prevent damage to sump.
22.Remove 4 bolts and nut, remove engine LH
rear mounting.
23.Remove 4 bolts and nut, remove engine RH
rear mounting. 24.Remove bolt securing gearbox oil cooler pipe
clips to engine.
25.Remove bolt and 2 nuts securing clamps to oil
cooler pipes and remove clamps.
26.Loosen gearbox oil cooler pipe unions, release
pipes from gearbox and discard 'O' rings.
CAUTION: Always fit plugs to open
connections to prevent contamination.