manual transmission LAND ROVER DISCOVERY 2002 User Guide

ENGINE MANAGEMENT SYSTEM - V8
18-2-50 DESCRIPTION AND OPERATION
In the case of a VSS failure on vehicles with automatic gearboxes, the ECM applies default values derived from the
EAT ECU. There are no default values for manual gearbox vehicles.
The VSS can fail in the following ways:
lWiring short circuit to vehicle supply.
lWiring short circuit to vehicle earth.
lWiring open circuit.
In the event of a VSS failure, any of the following symptoms may be observed:
lMIL illuminated after 2 driving cycles (NAS only).
lVehicle speed limiting disabled (manual transmission vehicles only).
lSLABS/HDC warning lamp on and audible warning.
Should a malfunction of the component occur the following fault codes may be evident and can be retrieved by
TestBook:
Rough road signal
When the vehicle travels across rough terrain, or on rough roads instability becomes evident in the drive train. The
ECM could interpret these vibrations as a 'false misfire'. To counteract this 'false misfire' the SLABS ECU generates
a rough road signal, sends it to the ECM so that the ECM can suspend misfire detection for as long as the vehicle is
travelling on the 'rough road'.
Function
Input for the rough road signal is measured via pin 34 of connector C0637 of the ECM. The SLABS ECU generates
a PWM signal that varies in accordance with changing road conditions. The rough road PWM signal operates at a
frequency of 2.33 Hz
± 10%. The significance of changes in the PWM signal are shown in the following table:
The rough road signal can fail in the following ways:
lHarness or connector damage
lSLABS failure — wheel speed sensor
A rough road signal failure may be evident from the following:
lHDC / ABS warning light on
P Code J2012 Description Land Rover Description
P0500 Vehicle speed sensor malfunction VSS short or open circuit
P0501 Vehicle speed sensor range/performance VSS implausible
PWM signal Indication
<10% Electrical short circuit to ground
25% ± 5 % Smooth road
50% ± 5 % SLABS error
75% ± 5% Rough road
>90% Electrical short circuit to battery voltage

ENGINE MANAGEMENT SYSTEM - V8
DESCRIPTION AND OPERATION 18-2-51
Should a malfunction of the rough road signal occur, the following fault codes may be evident and can be retrieved
by TestBook:
Hill Descent Control (HDC) signal
The ECM transmits throttle angle, engine torque, engine identification (Td5 or V8), and transmission type (automatic
or manual) data to the SLABS ECU to support the Hill Descent Control system. The information is transmitted via a
0 – 12V pulse width modulated (PWM) signal at a frequency of 179.27 Hz.
Function
The HDC signal output from the ECM is via pin 29 of connector C0636. The ECM generates a PWM signal that varies
in pulse width in accordance with changing throttle angle or engine torque. The throttle angle data is transmitted on
pulses 1, 3, 5 and 37. The engine torque data is transmitted on pulses 2,4,6 and 38. The engine and transmission
information is transmitted on pulse 39. A synchronising pulse is transmitted after every 39th pulse.
The HDC signal can fail in the following ways:
lHarness or connector damage
A HDC signal failure may be evident from the following:
lHDC / ABS warning light on
lHDC inoperative
lAudible warning
Should a malfunction of the HDC signal occur, the following fault codes may be evident and can be retrieved by
TestBook:
Low fuel level signal
When the fuel level in the fuel tank becomes low enough to illuminate the low fuel level warning lamp in the instrument
cluster, the instrument cluster generates a low fuel level signal. If the low fuel level signal is present during the ECM
misfire detection function the ECM can use it to check for a 'false misfire'.
Conditions
The fuel sender generates the low fuel level signal when the fuel sender resistance is greater than 158
± 8 ohms.
P Code J2012 Description Land Rover Description
P1590 ABS rough road signal circuit malfunction Hardware is OK, but SLABS ECU is sending an error
signal
P1591 ABS rough road signal circuit low Signal from SLABS ECU short circuit to earth
P1592 ABS rough road signal circuit high Signal from SLABS ECU short circuit to vehicle battery
supply
P Code J2012 Description Land Rover Description
P1663 Throttle angle/Torque signal circuit malfunction SLABS HDC link open circuit
P1664 Throttle angle/Torque signal circuit low SLABS HDC link short circuit to ground
P1665 Throttle angle/Torque signal circuit high SLABS HDC link short circuit to battery voltage

ENGINE MANAGEMENT SYSTEM - V8
DESCRIPTION AND OPERATION 18-2-53
Function
The CAN system uses a twisted pair of wires to form the 'data bus' to minimise electrical interference. This method of
serial interface is very reliable and very fast. The information messages are structured so that each of the receivers
(ECM or EAT ECU) is able to interpret and react to the messages sent.
The CAN 'data bus' is directly connected between pin 36 of connector C0637 of the ECM and pin 16 of connector
C0193 at the EAT ECU, and pin 37 of connector C0637 of the ECM and pin 44 of connector C0193 at the EAT ECU.
The CAN system can fail in the following ways:
lCAN data bus wiring open circuit.
lCAN data bus wiring short circuit.
In the event of a CAN data bus failure any of the following symptoms may be observed:
lMIL illuminated after 2 drive cycles (NAS only).
lEAT defaults to 3rd gear only.
lHarsh gearshifts.
l'Sport' and 'manual' lights flash alternately.
Should a malfunction of the component occur the following fault codes may be evident and can be retrieved by
TestBook.
Drive cycles
The following are the TestBook drive cycles:

Drive cycle A:
1Switch on the ignition for 30 seconds.
2Ensure engine coolant temperature is less than 60
°C (140°F).
3Start the engine and allow to idle for 2 minutes.
4Connect TestBook and check for fault codes.

Drive cycle B:
1Switch ignition on for 30 seconds.
2Ensure engine coolant temperature is less than 60
°C (140°F).
3Start the engine and allow to idle for 2 minutes.
4Perform 2 light accelerations (0 to 35 mph (0 to 60 km/h) with light pedal pressure).
5Perform 2 medium accelerations (0 to 45 mph (0 to 70 km/h) with moderate pedal pressure).
6Perform 2 hard accelerations (0 to 55 mph (0 to 90 km/h) with heavy pedal pressure).
7Allow engine to idle for 2 minutes.
8Connect TestBook and with the engine still running, check for fault codes.
P Code J2012 Description Land Rover Description
P0600 Serial communication link malfunction CAN time out
P1776 Transmission control system torque interface
malfunctionEAT torque interface error

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
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
44-16 DESCRIPTION AND OPERATION
Warning lamps
Warning lamps and selector lever position indication
1Transmission temperature warning lamp (red)
2Gear selector lever position indication
3Sport mode warning lamp (green)
4Manual mode warning lamp (green)
Illumination for each warning lamp is provided by a non serviceable LED.

AUTOMATIC GEARBOX - ZF4HP22 - 24
DESCRIPTION AND OPERATION 44-17
Operation
Refer to illustration.

+ AUTOMATIC GEARBOX - ZF4HP22 - 24, DESCRIPTION AND OPERATION, Control schematic.
When the ignition is switched on, a bulb check is performed on the transmission temperature warning lamp and the
mode warning lamps by the instrument pack and the EAT ECU respectively. The warning lamps are illuminated for
approximately 3 seconds and then extinguished.
The gear position switch outputs are monitored by the BCU and the EAT ECU. The BCU outputs gear position signals
to illuminate the position indicators each side of the gear selector lever and on the odometer LCD in the instrument
pack.
In D, 3, 2, and 1, the EAT ECU outputs control signals to the gearbox to select the required gear.
In D, all forward gears are available for selection by the EAT ECU. In 3, 2 and 1, a corresponding limit is imposed on
the highest gear available for selection. When R is selected, reverse gear only engages if the vehicle is stationary or
moving at 5 mph (8 km/h) or less. When R is deselected, reverse gear only disengages if the vehicle is moving at 4
mph (6 km/h) or less.
Selector lever interlock (where fitted)
The interlock solenoid on the selector lever is de-energised unless the foot brake is applied while the ignition is on.
While de-energised, the interlock solenoid allows the selector lever to move through the range unless P is selected.
On entering the P position, the interlock solenoid engages a latch which locks the selector lever. When the ignition is
on and the foot brake is applied, the BCU energises the interlock solenoid, which disengages the latch and allows the
selector lever to be moved out of P.
Economy, sport and manual modes
During the power-up procedure after the ignition is switched on, the EAT ECU defaults to an economy mode. Pressing
the mode switch causes the EAT ECU to change between the economy mode and the sport or the manual mode,
depending on the range selected on the transfer box:
lIf the transfer box is in high range, the EAT ECU changes to the sport mode and illuminates the sport mode
warning lamp in the instrument pack. In the sport mode the gearbox is more responsive to accelerator pedal
movement. Downshifts occur earlier and upshifts occur later.
lIf the transfer box is in low range, the EAT ECU changes to the manual mode and illuminates the manual mode
warning lamp in the instrument pack. Kickdown is disabled and the EAT ECU maintains the gearbox in the gear
selected on the selector lever (D = 4th gear) to give improved off road performance. Downshifts occur only to
prevent the engine stalling. From a standing start, the vehicle pulls away in 1st gear and, if a higher gear is
selected, upshifts almost immediately to the selected gear (shifts of more than one gear can occur).
After a second press of the mode switch the EAT ECU reverts to the economy mode, for the range selected on the
transfer box, and extinguishes the related mode warning lamp in the instrument pack.
Shift control
To provide the different driving characteristics for each mode of operation, the EAT ECU incorporates different shift
maps of throttle position/engine speed. Base shift points are derived from the appropriate shift map. When a shift is
required, the EAT ECU sends a request to the ECM for a reduction in engine torque, in order to produce a smoother
shift. The percentage of torque reduction requested varies according to the operating conditions at the time of the
request. When the EAT ECU receives confirmation of the torque reduction from the ECM, it then signals the shift
solenoid valves in the gearbox to produce the shift. To further improve shift quality, the EAT ECU also signals the
pressure regulating solenoid valve to modulate the hydraulic pressure and so control the rate of engagement and
disengagement of the brake clutches.

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

BRAKES
DESCRIPTION AND OPERATION 70-3
1ABS sensor
2ABS modulator
3Return pump relay
4SLABS ECU
5Brake lamp relay
6Centre high mounted stop lamp
7LH brake lamp
8RH brake lamp
9Instrument pack
10Body control unit
11Reverse lamp switch (manual gearbox)
12Diagnostic socket
13HDC switch
14Transmission high/low switch
15Centre differential lock switch
16Engine control module
17Battery power supply
18Ignition power supply

BRAKES
70-36 REPAIRS
Cable - handbrake
$% 70.35.25
Remove
1.Remove centre console.

+ INTERIOR TRIM COMPONENTS,
REPAIRS, Console - centre - automatic
models.

+ INTERIOR TRIM COMPONENTS,
REPAIRS, Console - centre - manual
models.
2.Remove clip and clevis pin securing cable to
hand brake lever.
3.Remove brake shoes from hand brake
assembly.

+ BRAKES, REPAIRS, Brake shoes -
handbrake.
4.From below the vehicle, pull handbrake cable
through transmission tunnel.
5.Release handbrake cable from backplate. Refit
1.Fit and secure handbrake cable to backplate.
2.Position hand brake cable through
transmission tunnel.
3.Fit brake shoes to hand brake assembly.

+ BRAKES, REPAIRS, Brake shoes -
handbrake.
4.Align cable to hand brake lever and secure with
clip and clevis pin.
5.Fit centre console.

+ INTERIOR TRIM COMPONENTS,
REPAIRS, Console - centre - automatic
models.

+ INTERIOR TRIM COMPONENTS,
REPAIRS, Console - centre - manual
models.
6.Adjust handbrake.

+ BRAKES, ADJUSTMENTS,
Handbrake.