2002 LAND ROVER DISCOVERY warning

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
44-20 DESCRIPTION AND OPERATION
P1601
(4)* ECU, EEPROM
checksumLimp home mode in low and high ranges. Shift
pressure to maximum, harsh gear shifts/
engagement.On On
P1606
(3)* EEPROM No apparent effect On†Off
P1606
(6)* Watchdog No apparent effect On On
P1612
(2)* Solenoid valves power
supply relay, sticking
closed or open circuitLimp home mode in low and high ranges. Shift
pressure to maximum, harsh gear shifts/
engagement.On On
P1613
(1)* Solenoid valves power
supply relay, sticking
open or short circuitLimp home mode in low and high ranges. Shift
pressure to maximum, harsh gear shifts/
engagement.On On
P1705
(39)Transmission high/low
range, implausible inputNo apparent effect On Off
P1810
(12, 13)Sport/Manual warning
lamp circuit faultLamp fails bulb check or is permanently
illuminated. No effect on gearbox operation.On Off
P1841
(16)* CAN bus fault Maintains current gear in low range, limp home
mode in high range. Shift pressure to maximum,
harsh gear shifts/engagement.On On
P1842
(15)* CAN level monitoring Maintains current gear in low range, limp home
mode in range. Shift pressure to maximum, harsh
gear shifts/engagement.On On
P1843
(17)* CAN time-out
monitoringMaintains current gear in low range, limp home
mode in high range. Shift pressure to maximum,
harsh gear shifts/engagement.On On
P1884
(11)* CAN message: Engine
friction invalidNo apparent effect. On Off
P1884
(18)* CAN message: Throttle
position invalidSubstitute throttle angle of 50% adopted. No
kickdown. Operates in economy modes only.On On
P1884
(19)CAN message: Engine
temperature invalidSubstitute engine temperature derived from other
inputs. No apparent effect.On Off
P1884
(20)CAN message: Road
speed invalidNo apparent effect On Off
P1884
(33, 34)* CAN message: Engine
torque invalidSubstitute engine torque of derived from other
inputs. May affect shift quality.On Off
P1884
(35)* CAN message: Engine
speed invalidMaintains current gear in low range, limp home
mode in high range. Shift pressure to maximum,
harsh gear shifts/engagement.On On
P1884
(37)CAN message: Engine
air intake temperature
invalidNo apparent effect. On Off
P1844
(38)Altitude shift control
invalidNo reduced torque compensation, possible
reduction in performance/ driveability at altitude
or high ambient temperatures.On Off
* = Emissions (OBD II) relevant
†On = MIL illuminates immediately (in all other faults, MIL On = illuminates in the 2nd consecutive drive cycle if fault still
present)Fault code,
OBD II
(TestBook)Fault description Effect Warning lamp
illumination
MIL Sport/
Manual

PROPELLER SHAFTS
REPAIRS 47-5
REPAIRS
Propeller shaft - front
$% 47.15.02
Remove
1.Raise front of vehicle.
WARNING: Do not work on or under a
vehicle supported only by a jack. Always
support the vehicle on safety stands.
2.If same components to be refitted, reference
mark propeller shaft and mating components.
3.Remove 8 nuts and bolts securing propeller
shaft to differential and transfer gearbox
flanges.
4.Remove propeller shaft.
Refit
1.Clean propeller shaft flanges and mating
faces.
2.Position propeller shaft to transfer gearbox
and differential and tighten nuts and bolts to 47
Nm (35 lbf. ft).
3.Remove stand(s) and lower vehicle.
Propeller shaft - rear
$% 47.15.03
Remove
1.Raise rear of vehicle.
WARNING: Do not work on or under a
vehicle supported only by a jack. Always
support the vehicle on safety stands.
2.If same components are to be refitted,
reference mark propeller shaft and mating
components.
3.Remove 4 nuts and bolts securing propellor
shaft to transfer gearbox flange.
4.Remove 3 nuts and bolts securing propeller
shaft to flexible coupling.
5.Remove propeller shaft.
Refit
1.Clean propeller shaft flanges and mating
faces.
2.Position propeller shaft to transfer gearbox and
flexible coupling.
3.Fit nuts and bolts securing propeller shaft to
transfer gearbox and tighten to 47 Nm (35
lbf.ft).
4.Fit nuts and bolts securing propeller shaft to
flexible coupling and tighten to 76 Nm (56 lbf.ft).
5.Lower vehicle.
M51 0043A
2
3

PROPELLER SHAFTS
47-6 REPAIRS
Flexible coupling
$% 47.20.08
Remove
1.Raise rear of vehicle.
WARNING: Do not work on or under a
vehicle supported only by a jack. Always
support the vehicle on safety stands.
2.If same components to be refitted, reference
mark flexible coupling and mating components.
3.Remove 3 nuts and bolts securing propeller
shaft to flexible coupling.
4.Move propeller shaft forwards to release from
flexible coupling and differential drive flange
spigot.
5.Tie propeller shaft aside.
6.Remove 3 nuts and bolts securing flexible
coupling to differential drive flange and remove
flexible coupling.Refit
1.Ensure flexible coupling, spigot and drive
flanges are clean.
2.Align the arrows on the flexible coupling with
the securing bolt positions as illustrated. Fit
flexible coupling to differential drive flange and
tighten nuts and bolts to 76 Nm (56 lbf.ft).
3.Fit propeller shaft to spigot and flexible
coupling. Tighten nuts and bolts to 76 Nm (56
lbf.ft).
4.Remove stand(s) and lower vehicle.

REAR AXLE
REPAIRS 51-5
REPAIRS
Differential - assembly
$% 51.15.01
Remove
1.Raise rear of vehicle.
WARNING: Do not work on or under a
vehicle supported only by a jack. Always
support the vehicle on safety stands.
2.Drain oil from differential.

+ MAINTENANCE, PROCEDURES,
Front and rear axle.
3.If same components are to be refitted,
reference mark propeller shaft and mating
components.
4.Remove 3 nuts and bolts securing flexible
coupling to pinion flange. Release propeller
shaft and tie aside.
5.Using tool LRT-51-008, extract the centralising
peg from the pinion flange. Remove the
centralising peg from the tool.6.Remove LH and RH rear brake discs.

+ BRAKES, REPAIRS, Brake disc -
rear.
7.Disconnect each ABS sensor multiplug.
8.Release each harness from brake hose and
hose bracket.
9.Remove 4 bolts securing each rear wheel hub
to rear axle.
M51 0041B
5
4
M51 0056
LRT-51-008

REAR AXLE
REPAIRS 51-7
Seal - differential pinion
$% 51.20.01
Remove
1.Raise rear of vehicle.
WARNING: Do not work on or under a
vehicle supported only by a jack. Always
support the vehicle on safety stands.
2.Reference mark rear propeller shaft for
reassembly.
3.Remove 3 nuts and bolts securing flexible
coupling to pinion flange. Tie propeller shaft
aside.
4.Using tool LRT-51-008, extract the centralising
peg from the pinion flange. Remove the
centralising peg from the tool.5.Using tool LRT-51-003 to restrain pinion
flange, remove bolt and washer securing pinion
flange. Remove pinion flange.
6.Position container to catch oil spillage
7.Using a suitable lever, remove pinion oil seal.
Take care to avoid damage to oil seal
recess.
M51 0043A
2
3
M51 0056
LRT-51-008
M51 0047A
LRT-51-003

FRONT AXLE
REPAIRS 54-5
REPAIRS
Differential - assembly
$% 54.10.01
Remove
1.Raise front of vehicle.
WARNING: Do not work on or under a
vehicle supported only by a jack. Always
support the vehicle on safety stands.
2.Remove front road wheels.
3.Drain oil from differential.

+ MAINTENANCE, PROCEDURES,
Front and rear axle.
4.If same components to be refitted, reference
mark propeller shaft and mating components.
5.Remove 4 nuts and bolts securing propeller
shaft to differential. Release propeller shaft and
tie aside.
6.Remove LH and RH front brake discs.

+ BRAKES, REPAIRS, Brake disc -
front.7.Disconnect each ABS sensor multiplug.
8.Release each harness from brake hose and
hose bracket.

FRONT AXLE
REPAIRS 54-7
13.Fit front brake discs.

+ BRAKES, REPAIRS, Brake disc -
front.
14.Fit front road wheels and tighten nuts to 140
Nm (103 lbf.ft).
15.Remove stand(s) and lower vehicle.
16.Fill differential with oil.

+ MAINTENANCE, PROCEDURES,
Front and rear axle.
Seal - differential pinion
$% 54.10.20
Remove
1.Raise front of vehicle.
WARNING: Do not work on or under a
vehicle supported only by a jack. Always
support the vehicle on safety stands.
2.Reference mark front propeller shaft for
reassembly.
3.Remove 4 nuts and bolts securing propeller
shaft to differential. Release propeller shaft and
tie aside.
4.Using LRT-51-003 to restrain pinion flange,
remove bolt and washer securing pinion flange.
Remove pinion flange.
5.Position container to catch oil spillage.