2002 LAND ROVER DISCOVERY wiring

GENERAL INFORMATION
03-17
Electrical Precautions
General
The following guidelines are intended to ensure the
safety of the operator while preventing damage to the
electrical and electronic components fitted to the
vehicle. Where necessary, specific precautions are
detailed in the individual procedures of this manual.
Equipment
Prior to commencing any test procedure on the
vehicle ensure that the relevant test equipment is
working correctly and any harness or connectors are
in good condition. It is particularly important to check
the condition of the lead and plugs of mains operated
equipment.
Polarity
Never reverse connect the vehicle battery and
always ensure the correct polarity when connecting
test equipment.
High voltage circuits
Whenever disconnecting live ht circuits always use
insulated pliers and never allow the open end of the
ht lead to contact other components, particularly
ECU's. Exercise caution when measuring the voltage
on the coil terminals while the engine is running, high
voltage spikes can occur on these terminals.
Connectors and harnesses
The engine compartment of a vehicle is a particularly
hostile environment for electrical components and
connectors:
lAlways ensure electrically related items are dry
and oil free before disconnecting and
connecting test equipment.
lEnsure disconnected multiplugs and sensors
are protected from being contaminated with oil,
coolant or other solutions. Contamination could
impair performance or result in catastrophic
failure.
lNever force connectors apart using tools to
prise apart or by pulling on the wiring harness.
lAlways ensure locking tabs are disengaged
before disconnection, and match orientation to
enable correct reconnection.
lEnsure that any protection (covers, insulation
etc.) is replaced if disturbed.Having confirmed a component to be faulty:
lSwitch off the ignition and disconnect the
battery.
lRemove the component and support the
disconnected harness.
lWhen replacing the component keep oily hands
away from electrical connection areas and push
connectors home until any locking tabs fully
engage.
Battery disconnection
Before disconnecting the battery, disable the alarm
system and switch off all electrical equipment. If the
radio is to be serviced, ensure the security code has
been deactivated.
CAUTION: To prevent damage to electrical
components, always disconnect the battery
when working on the vehicle's electrical system.
The ground lead must be disconnected first and
reconnected last.
CAUTION: Always ensure that battery leads are
routed correctly and are not close to any
potential chafing points.
Battery charging
Only recharge the battery with it removed from the
vehicle. Always ensure any battery charging area is
well ventilated and that every precaution is taken to
avoid naked flames and sparks.
Ignition system safety precautions
The vehicle's ignition system produces high voltage
and the following precautions should be observed
before carrying out any work on the system.
WARNING: Before commencing work on an
ignition system, ensure all high tension
terminals, adapters and diagnostic equipment
are adequately insulated and shielded to prevent
accidental personal contacts and minimise the
risk of shock. Wearers of surgically implanted
pacemaker devices should not be in close
proximity of ignition circuits or diagnostic
equipment.
Disciplines
Switch off the ignition prior to making any connection
or disconnection in the system to prevent electrical
surges caused by disconnecting 'live' connections
damaging electronic components.
Ensure hands and work surfaces are clean and free
of grease, swarf, etc. Grease collects dirt which can
cause electrical tracking (short-circuits) or high-
resistance contacts.
When handling printed circuit boards, treat with care
and hold by the edges only; note that some electronic
components are susceptible to body static.

GENERAL INFORMATION
03-21
WARNING: Do not use a multimeter or other
general purpose test equipment on SRS system
components or accidental deployment may
occur. Use only Testbook to diagnose system
faults.
SRS harnesses and connectors
Always observe the following precautions with
regard to SRS systems:
lNever attempt to modify, splice or repair SRS
wiring. SRS wiring can be identified by a special
yellow outer protective covering (black with
yellow stripe protective coverings are
sometimes used).
lNever install electronic equipment (such as a
mobile telephone, two way radio or in-car
entertainment system) in such a way that it
could generate electrical interference in the
airbag harness. Seek specialist advice when
installing such equipment.CAUTION: Always ensure the SRS harness is
routed correctly. Avoid trapping or pinching the
SRS harness. Look out for possible chafing
points.
CAUTION: Ensure all SRS harness connectors
are mated correctly and securely fastened. Do
not leave the connectors hanging loose.
CAUTION: Do not allow the airbag module to
hang by the airbag harness.

GENERAL INFORMATION
03-27
Body repairs often involve the removal of mechanical
and electrical units and associated wiring. Where
necessary, refer to the relevant section of the
Workshop Manual for removal and refitting
instructions.
Taking into consideration the differences in body
styles, suspension systems and engine and
transmission layouts, the location of the following
components as applicable to a particular vehicle is
critical:
lFront suspension upper damper mountings on
RH and LH chassis longitudinals.
lFront suspension or sub frame mountings.
lEngine mountings on RH and LH chassis
longitudinals.
lRear suspension upper damper mountings on
RH and LH chassis longitudinals.
lRear suspension mountings or lower pivots.
Additional points which can be used to check
alignment and assembly are:
lInner holes in cross member - side - main floor.
lHoles in front bulkhead.
lHoles in rear longitudinals.
lHoles in rear lower panels.
Apertures for windscreen, rear screen, bonnet and
doors can be measured and checked using the
dimensional information provided and also by
offering up an undamaged component as a gauge.
Straightening
Whenever possible, structural members should be
cold straightened under tension. Do not attempt to
straighten with a single pull but rework the damaged
area using a series of pulls, releasing tension
between each stage and using the opportunity to
check alignment.
Body jig
Unless damage is limited to cosmetic panels, all
repair work to body members must be carried out on
a body jig, to ensure that impact damage has not
spread into more remote parts of the structure.
Mounting on a jig will also ensure that the
straightening and panel replacement procedures do
not cause further distortion.
If original dimensions cannot be satisfactorily
restored by these methods, damaged structural
members should be replaced. Damaged areas
should be cut away using a high speed saw, NOT an
oxy-acetylene torch.
As a rule, body dimensions are symmetrical about
the centre line. A good initial check for distortion is
therefore to measure diagonally and to investigate
apparent differences in dimensions.Inspection
Every accident produces individual variations in
damage. Each repair is influenced by the extent of
the damage and the facilities and equipment
available for its rectification.
Most accident damage can be visually inspected and
the approximate extent of damage assessed.
Sometimes deformation will extend beyond the
directly damaged area, and the severity of this must
be accurately established so that steps can be taken
to restore critical body components to their original
dimensions. An initial check can be carried out by
means of drop checks or, preferably, trammels.
Gauges are available which will accurately check for
body twist.

EMISSION CONTROL - V8
DESCRIPTION AND OPERATION 17-2-13
The heated oxygen sensor is an integral part of the exhaust emission control system and is used in conjunction with
the catalytic converters and the engine management control unit to ensure that the air:fuel mixture ratio stays around
the stoichiometric point of
λ = 1, where the catalytic converters are most effective. Combinations of four (NAS only)
or two heated lambda sensors are used in the exhaust system dependent on market legislation.
The heated oxygen sensor is screwed into threaded mountings welded into the top of the front exhaust pipes at
suitable locations. They are used to detect the level of residual oxygen in the exhaust gas to provide an instantaneous
indication of whether combustion is complete. By positioning sensors in the stream of exhaust gases from each
separate bank of the exhaust manifold, the engine management system is better able to control the fuelling
requirements on each bank independently of the other, so allowing much closer control of the air:fuel ratio and
optimising catalytic converter efficiency.
Two pre-catalytic converter heated oxygen sensors are mounted in the front pipes for monitoring the oxygen content
of the exhaust gas. NAS models also have two additional post-catalytic converter heated oxygen sensors in the
exhaust front pipe.
CAUTION: HO2 sensors are easily damaged by dropping, over torquing, excessive heat or contamination.
Care must be taken not to damage the sensor housing or tip.
The oxygen sensors consist of a ceramic body (Galvanic cell) which is a practically pure oxygen-ion conductor made
from a mixed oxide of zirconium and yttrium. The ceramic is then coated with gas-permeable platinum, which when
heated to a sufficiently high temperature (
≥ 350° C) generates a voltage which is proportional to the oxygen content
in the exhaust gas stream.
The heated oxygen sensor is protected by an outer tube with a restricted flow opening to prevent the sensor's
ceramics from being cooled by low temperature exhaust gases at start up. The post-catalytic sensors have improved
signal quality, but a slower response rate.
The pre-catalytic and post-catalytic converter sensors are not interchangeable, and although it is possible to mount
them in transposed positions, their harness connections are of different gender and colour. It is important not to
confuse the sensor signal pins; the signal pins are gold plated, whilst the heater supply pins are tinned,
mixing them up will cause contamination and adversely affect system performance.
Each of the heated oxygen sensors have a four pin connector with the following wiring details:
lSensor signal ground (grey wire – connects to engine management ECM)
lSensor signal (black wire – connects to engine management ECM)
lHeater drive (white wire – connects to engine management ECM)
lHeater supply (white wire – connects to fuse 2, underbonnet fuse box)
The ECM connector pins for exhaust emission control are listed in the following table:
ECM Connector 2 (C635) pin-out details for exhaust emission control system
Pin Number Function Signal Type Control
2-01 Post-cat sensor heater (RH) - NAS only Output, Drive PWM, 12 - 0V
2-07 Post-cat sensor heater (LH) - NAS only Output, Drive PWM, 12 - 0V
2-08 Post-cat sensor (RH) - NAS only Ground, Signal 0V
2-09 Pre-cat sensor (LH) Ground, Signal 0V
2-10 Pre-cat sensor (RH) Ground, Signal 0V
2-11 Post-cat sensor (LH) - NAS only Ground, Signal 0V
2-13 Pre-cat sensor heater (RH) Output, Drive PWM, 12 - 0V
2-14 Post-cat sensor (RH) - NAS only Input, Signal Analogue, 0 - 1V
2-15 Pre-cat sensor (LH) Input, Signal Analogue, 0 - 1V
2-16 Pre-cat sensor (RH) Input, Signal Analogue, 0 - 1V
2-17 Post-cat sensor (LH) - NAS only Input, Signal Analogue, 0 - 1V
2-19 Pre-cat sensor heater (LH) Output, Drive PWM, 12 - 0V

EMISSION CONTROL - V8
17-2-20 DESCRIPTION AND OPERATION
Purge valve operation is controlled by the engine control module (ECM). The purge valve has a two-pin electrical
connector which links to the ECM via the engine harness. Pin-1 of the connector is the power supply source from fuse
2 in the engine compartment fusebox, and pin-2 of the connector is the switched earth from the ECM (pulse width
modulated (PWM) signal) which is used to control the purge valve operation time. Note that the harness connector
for the purge valve is black, and must not be confused with the connector for the Secondary Air Injection
vacuum solenoid valve which is grey.
When the purge valve is earthed by the ECM, the valve opens to allow hydrocarbons stored in the EVAP canister to
be purged to the engine inlet manifold for combustion.
If the purge valve breaks or becomes stuck in the open or closed position, the EVAP system will cease to function
and there are no default measures available. The ECM will store the fault in memory and illuminate the MIL warning
lamp if the correct monitoring conditions have been achieved (i.e. valve status unchanged for 45 seconds after engine
has been running for 15 minutes). If the purge valve is stuck in the open position, a rich air:fuel mixture is likely to
result at the intake manifold, this could cause the engine to misfire and the fuelling adaptions will change.
The following failure modes are possible:
lSticking valve
lValve blocked
lConnector or harness wiring fault (open or short circuit)
lValve stuck open
If the purge valve malfunctions, the following fault codes may be stored in the ECM diagnostic memory, which can be
retrieved using 'Testbook':
P-code Description
P0440Purge valve not sealing
P0444Purge valve open circuit
P0445Purge valve short circuit to ground
P0443Purge valve short circuit to battery voltage

EMISSION CONTROL - V8
DESCRIPTION AND OPERATION 17-2-21
Canister Vent Solenoid (CVS) unit – (NAS with vacuum type, fuel evaporation leak detection system only)
1CVS unit
2Mounting bracket
3Spring clips to pipe from EVAP canister
4Harness connector
The canister vent solenoid (CVS) valve is mounted on a slide-on bracket which is riveted to the cruise control bracket
at the right hand side of the engine compartment. The vent pipe from the EVAP canister is connected to a stub pipe
on the CVS unit via a hose and plastic pipe combination. A two-pin connector links to the engine management ECM
via the engine harness for solenoid control; one of the wires is the supply feed from fuse No.2 in the engine
compartment fusebox, the other wire is the valve drive line to the ECM. The solenoid is operated when the ECM
grounds the circuit.
The valve is normally open, allowing any build up of air pressure within the evaporation system to escape, whilst
retaining the environmentally harmful hydrocarbons in the EVAP canister. When the ECM is required to run a fuel
system test, the CVS valve is closed to seal the system. The ECM is then able to measure the pressure in the fuel
evaporative system using the fuel tank pressure sensor.
The ECM performs electrical integrity checks on the CVS valve to determine wiring or power supply faults. The ECM
can also detect a valve blockage if the signal from the fuel tank pressure sensor indicates a depressurising fuel tank
while the CVS valve should be open to atmosphere.

EMISSION CONTROL - V8
17-2-22 DESCRIPTION AND OPERATION
The following failure modes are possible:
lConnector or harness wiring fault (open or short circuit)
lValve stuck open or shut
lValve blocked
If the CVS valve malfunctions, the following fault codes may be stored in the ECM diagnostic memory, which can be
retrieved using 'Testbook':
Fuel Tank Pressure Sensor (NAS vehicles with vacuum type leak detection system only)
1Ambient pressure
2Tank pressure
3Sensor cell
The fuel tank pressure sensor is located in the top flange of the fuel tank sender / fuel pump module and is a non-
serviceable item (i.e. if the sensor becomes defective, the complete fuel tank sender unit must be replaced). The fuel
tank pressure sensor connector is accessible through the fuel pump access hatch in the boot area floor of the vehicle.
The pressure sensor is a piezo-resistive sensor element with associated circuitry for signal amplification and
temperature compensation. The active surface is exposed to ambient pressure by an opening in the cap and by the
reference port. It is protected from humidity by a silicon gel. The tank pressure is fed up to a pressure port at the back
side of the diaphragm.
P-code Description
P0446CVS valve / pipe blocked
P0447CVS valve open circuit
P0448CVS valve short circuit to ground
P0449CVS valve short circuit to battery voltage

ENGINE MANAGEMENT SYSTEM - TD5
18-1-10 DESCRIPTION AND OPERATION
Mass Air Flow (MAF) sensor
The MAF sensor is located in the intake system between the air filter housing and the turbocharger. The ECM uses
the information generated by the MAF to control exhaust gas recirculation (EGR).
The MAF sensor works on the hot film principal. The MAF sensor has 2 sensing elements contained within a film. One
element is controlled at ambient temperature e.g. 25
°C (77 °F) while the other is heated to 200 °C (392 °F) above
this temperature e.g. 225
°C (437 °F). As air passes through the MAF sensor the hot film will be cooled. The current
required to keep the constant 200
°C (392 °F) difference provides a precise although non-linear signal of the air drawn
into the engine. The MAF sensor sends a voltage between 0 and 5 volts to the ECM proportional to the mass of the
incoming air. This calculation allows the ECM to set the EGR ratio for varying operating conditions.
Input/Output
The MAF sensor receives battery voltage from the main relay in the engine compartment fuse box. Signal output from
the MAF sensor to the ECM is a variable voltage proportional to air drawn into the engine.
Input to the MAF sensor is via pin 5 of connector C0570 at the engine compartment fuse box. This 12 volt supply is
provided by the main relay via fuse 2 in the engine compartment fuse box. The MAF sensor receives the input voltage
at pin 3 of the sensor connector.
Output from the MAF sensor is measured at pin 11 of the ECM connector C0158. The earth path is via pin 20 of the
ECM connector C0158.
The MAF sensor can fail the following ways or supply incorrect signal:
lSensor open circuit.
lShort circuit to vehicle supply.
lShort circuit to vehicle earth.
lContaminated sensor element.
lDamaged sensor element.
lDamaged in wiring harness.
lMAF supplies incorrect signal (due to air leak or air inlet restriction).
In the event of a MAF sensor signal failure any of the following symptoms may be observed:
lDuring driving engine speed may dip, before recovering.
lDifficult starting.
lEngine stalls after starting.
lDelayed throttle response.
lEGR inoperative.
lReduced engine performance.
lMAF signal out of parameters.
The MIL will not illuminate in a MAF sensor failure, and the ECM will use a fixed default value from its memory.