1999 LAND ROVER DISCOVERY ignition

CONTENTS
CONTENTS 7
ENGINE MANAGEMENT SYSTEM - V8 .................................................. 18-2-1
DESCRIPTION AND OPERATION
Engine management component location - Passenger compartment ............................................ 18-2-1
Engine management component location - Engine compartment .................................................. 18-2-2
Engine management block diagram ............................................................................................... 18-2-4
Description - engine management .................................................................................................. 18-2-6
Operation - engine management .................................................................................................... 18-2-49
DESCRIPTION AND OPERATION
Cruise control component layout .................................................................................................... 18-2-61
Cruise control block diagram .......................................................................................................... 18-2-62
Description - cruise control ............................................................................................................. 18-2-63
Operation - cruise control................................................................................................................ 18-2-74
ADJUSTMENTS
Cable - throttle ............................................................................................................................. 18-2-77
Cable - cruise control .................................................................................................................... 18-2-77
REPAIRS
Spark plugs .................................................................................................................................. 18-2-79
Coil - ignition ................................................................................................................................. 18-2-80
Engine control module (ECM) ......................................................................................................... 18-2-81
Sensor - engine coolant temperature (ECT) ................................................................................ 18-2-82
Sensor - crankshaft position (CKP) ............................................................................................... 18-2-83
Sensor - radiator temperature ....................................................................................................... 18-2-84
Sensor - camshaft position (CMP) ................................................................................................. 18-2-84
Knock sensor (KS) .......................................................................................................................... 18-2-85
Air cleaner assembly ..................................................................................................................... 18-2-86
Element - air filter .......................................................................................................................... 18-2-87
Cable - throttle ................................................................................................................................ 18-2-88
Sensor - Mass Air Flow (MAF) ...................................................................................................... 18-2-89
Throttle Body................................................................................................................................... 18-2-90
Plenum chamber ............................................................................................................................. 18-2-91
Sensor - throttle position (TP) ....................................................................................................... 18-2-91
Valve - idle air control (IACV) ........................................................................................................ 18-2-92
Injectors ......................................................................................................................................... 18-2-92
Actuator - cruise control ................................................................................................................ 18-2-94
Vacuum control unit - up to 03MY................................................................................................... 18-2-94
Vacuum control unit - from 03MY ................................................................................................... 18-2-95
Cable - cruise control ..................................................................................................................... 18-2-96
Switch - cruise control (on/off) ........................................................................................................ 18-2-96
Switch - cruise control (set/resume) ............................................................................................... 18-2-97
Switch - clutch pedal - cruise control ............................................................................................ 18-2-97
ECU - Cruise control ..................................................................................................................... 18-2-98

GENERAL INFORMATION
03-15
Hose clips
Markings (4) are usually provided on the hose to
indicate the correct clip position. If no markings are
provided, position the clip directly behind the
retaining lip at the end of the stub as shown. Worm
drive clips should be oriented with the crimped side
of the drive housing (5) facing towards the end of the
hose, or the hose may become pinched between the
clip and the stub pipe retaining lip. Worm drive clips
should be tightened to 3 Nm (2 lbf.ft) unless
otherwise stated. Ensure that hose clips do not foul
adjacent components.
Heat protection
Always ensure that heatshields and protective
sheathing are in good condition. Replace if damage
is evident. Particular care must be taken when
routing hoses close to hot engine components, such
as the exhaust manifold and the Exhaust Gas
Recirculation (EGR) pipe. Hoses will relax and
deflect slightly when hot; ensure this movement is
taken into account when routing and securing hoses.
Rolling Road Testing
General
IMPORTANT: Use a four wheel rolling road for
brake testing if possible.
WARNING: Do not attempt to test ABS function
on a rolling road.
Four wheel rolling road
Provided that front and rear rollers are rotating at
identical speeds and that normal workshop safety
standards are applied, there is no speed restriction
during testing except any that may apply to the tyres.
Before testing a vehicle with anti-lock brakes on a
four wheel rolling road, disconnect the ABS
modulator. The ABS function will not work, the ABS
warning light will illuminate. Normal braking will be
available.
Two wheel rolling road
Up to 03MY
ABS will not function on a two wheel rolling road. The
ABS light will illuminate during testing. Normal
braking will be available.
If brake testing on a two wheel rolling road is
necessary, the following precautions should be
taken:
lPropeller shaft to the rear axle is removed.
lNeutral selected in gearbox.
When checking brakes, run engine at idle speed to
maintain servo vacuum.
From 03MY
The differential lock must be engaged for two wheel
rolling road testing. It will also be necessary to
disconnect the propeller shaft from the transfer box
output shaft driving the axle whose wheels are NOT
on the rolling road. Additionally, the ETC system
must be deactivated by either removing the 10 amp
fuse (Number 28, labelled ABS in the main fuse box)
or disconnecting the ABS modulator pump. This
must be done with the ignition OFF ; a fault in the
ABS system may still be recorded.
WARNING; VEHICLES NOT FITTED WITH A
DIFFERENTIAL LOCK MUST NOT BE TESTED
ON A ROLLING ROAD WHERE THE ROLLERS
ARE DRIVEN BY THE VEHICLE.

GENERAL INFORMATION
03-16
Fuel Handling Precautions
Fuel vapour is highly flammable and in confined
spaces is also explosive and toxic. The vapour is
heavier than air and will always fall to the lowest
level. The vapour can be easily distributed
throughout a workshop by air currents;
consequently, even a small spillage of fuel is
potentially very dangerous.
The following information provides basic precautions
which must be observed if fuel is to be handled
safely. It also outlines other areas of risk which must
not be ignored. This information is issued for basic
guidance only, if in doubt consult your local Fire
Officer.
General
Always have a fire extinguisher containing FOAM,
CO
2, GAS or POWDER close at hand when handling
or draining fuel or when dismantling fuel systems.
Fire extinguishers should also be located in areas
where fuel containers are stored.
Always disconnect the vehicle battery before
carrying out dismantling or draining work on a fuel
system.
Whenever fuel is being handled, drained or stored, or
when fuel systems are being dismantled, all forms of
ignition must be extinguished or removed; any
leadlamps must be flameproof and kept clear of
spillage.
WARNING: No one should be permitted to repair
components associated with fuel without first
having specialist training.
WARNING: Do not remove fuel system
components while the vehicle is over a pit.
Fuel tank draining
Fuel tank draining should be carried out in
accordance with the procedure outlined in the FUEL
DELIVERY section of this manual and observing the
following precautions.
WARNING: Fuel must not be extracted or drained
from any vehicle while it is over a pit. Extraction
or draining of fuel must be carried out in a well
ventilated area.
The capacity of containers must be more than
adequate for the amount of fuel to be extracted or
drained. The container should be clearly marked
with its contents and placed in a safe storage
area which meets the requirements of local
authority regulations.Fuel tank removal
When the fuel line is secured to the fuel tank outlet by
a spring steel clip, the clip must be released before
the fuel line is disconnected or the fuel tank is
removed. This procedure will avoid the possibility of
fumes in the fuel tank being ignited when the clip is
released.
As an added precaution, fuel tanks should have a
'FUEL VAPOUR' warning label attached to them as
soon as they are removed from the vehicle.
Fuel tank repairs - plastic tank
No attempt should be made to repair a plastic fuel
tank. If the structure of the tank is damaged, a new
tank must be fitted.
Body repairs
Plastic fuel pipes are particularly susceptible to heat,
even at relatively low temperature, and can be
melted by heat conducted from some distance away.
When body repairs involve the use of heat, all fuel
pipes which run in the vicinity of the repair area must
be removed, and the tank outlet plugged.
WARNING: If welding is to be carried out in the
vicinity of the fuel tank, the fuel system must be
drained and the tank removed before welding
commences.

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.

GENERAL INFORMATION
03-18
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.
Connectors should never be subjected to forced
removal or refit, especially inter-board connectors.
Damaged contacts can cause short-circuit and open-
circuit fault conditions.
Prior to commencing test, and periodically during a
test, touch a good vehicle body earth to discharge
static charge. Some electronic components are
vulnerable to the static electricity that may be
generated by the operator.
Grease for electrical connectors
Some under bonnet and under body connectors may
be protected against corrosion by the application of a
special grease during vehicle production. Should
connectors be disturbed in service, repaired or
replaced, additional grease should be applied: Part
No. BAU 5811, available in 150 gm tubs.
NOTE: The use of greases other than BAU 5811
must be avoided as they can migrate into relays,
switches etc. contaminating the contacts and leading
to intermittent operation or failure.
Supplementary Restraint System
Precautions
General
The Supplementary Restraint System (SRS)
provides active protection for vehicle occupants in
the event of a serious collision. The system
components include airbags and pretensioner seat
belts which are automatically deployed when a
severe frontal crash condition is detected.
In order to assure system integrity, it is essential that
the SRS system is regularly checked and maintained
so that it is ready for operation in the event of an
accident.
The SRS system contains components which could
be potentially hazardous to the service engineer if
not serviced and handled correctly. The following
guidelines are intended to alert the service engineer
to potential sources of danger and emphasise the
importance of ensuring integrity of the SRS
components fitted to the vehicle.
Where necessary, additional specific precautions are
detailed in the Restraint Systems section of this
Manual which should be referred to prior to
commencing repair operations.
It should be noted that these precautions are not
restricted to operations performed when servicing
the SRS system. The same care should be exercised
when working on ancillary systems and components
located in the vicinity of SRS components; these
include but are not limited to steering system (driver's
airbag), body and trim components (passenger's
airbag and seat belt pretensioners) and electrical
system components (SRS harnesses etc.).

GENERAL INFORMATION
03-19
WARNING: Do not use rear facing child seats in
the front passenger seat if the vehicle is fitted
with a passenger airbag.
WARNING: It is imperative that before any work
is undertaken on the SRS system the appropriate
information is read thoroughly.
WARNING: Replace the airbag every 10 years.
Do not install used SRS parts from another car.
When repairing an SRS system, always use
approved new parts.
Carefully inspect the airbag module before
installing it. Do not install an airbag module that
shows signs of being dropped or improperly
handled, such as dents, cracks or deformation.
Do not try to disassemble or tamper with the
airbag module.
Special bolts are necessary for installing the
airbag module. Do not use other bolts.
Preliminary procedures
The SRS system uses energy reserve capacitors
that keep the system active in the event of electrical
supply failure under crash conditions. It is necessary
to allow the capacitors sufficient time to discharge in
order to avoid the risk of accidental deployment.
Always remove the ignition key from the starter
switch, disconnect the vehicle battery and wait 10
minutes before commencing work on the SRS
system.
Carefully inspect any SRS component before
installation. Do not install any SRS component that
shows signs of damage such as dents, cracks or
deformity.Component handling
The SRS components are sensitive and potentially
hazardous if not handled correctly; always comply
with the following handling precautions:
lNever drop an SRS component. The airbag
Diagnostic Control Unit (DCU) is a particularly
shock sensitive device and must be handled
with extreme care. Airbag modules and seat belt
pretensioner units could deploy if subjected to a
strong shock.
lNever wrap your arms around an airbag
module. If an airbag module has to be carried,
hold it by the cover, with the cover uppermost
and the base away from your body.
lNever transport airbag modules or seat belt
pretensioners in the cabin of a vehicle. Always
use the luggage compartment of the vehicle for
carrying airbag modules and seat belt
pretensioner units.
WARNING: The airbag module contains sodium
azide which is poisonous and extremely
flammable. Contact with water, acid or heavy
metals may produce harmful or explosive
compounds. Do not dismantle, incinerate or
bring into contact with electricity, before the unit
has been deployed.

GENERAL DATA
04-9
Cooling system - Td5
Type Pressurised, spill return partial flow, thermostatically controlled
Cooling fans 11 blade axial flow on viscous coupling and 11 blade axial flow electric
Electric cooling fan switching points:
For A/C system:
⇒ On When vehicle speed is 50 mph (80 km/h) or less and ambient
temperature is 28 °C (82 °F) or more
⇒ Off When vehicle speed increases to 62.5 mph (100 km/h) or ambient
temperature decreases to 25 °C (77 °F)
For engine cooling during normal running:
⇒ On 110 °C (230 °F)
⇒ Off 105 °C (221 °F)
For engine cooling at ignition off (to counteract heat
soak):
⇒ On If, within 10 seconds of ignition off, engine coolant temperature is 105
°C (221 °F) or more
⇒ Off After 10 minutes or if engine coolant temperature decreases to 100 °C
(212 °F)
Coolant pump Centrifugal impeller, belt driven from crankshaft
Thermostat Waxstat with pressure relief valve
Thermostat opening temperature:
⇒ Initial opening 82 °C (179 °F)
⇒ Fully open 96 °C (204 °F)
Expansion tank cap relief valve - system operating
pressure1.4 bar (20.3 lbf.in
2)
Fuel cooler thermostat opening temperature 82°C (179°F)

GENERAL DATA
04-10
Cooling system - V8
Type Pressurised, spill return, thermostatically controlled water and
antifreeze mixture. Vertical flow radiator with remote header tank and
pump assisted
Cooling fans 9 blade axial flow on viscous coupling and 11 blade axial flow electric
Electric cooling fan switching points:
For A/C system:
⇒ On When vehicle speed is 50 mph (80 km/h) or less and ambient
temperature is 28 °C (82 °F) or more
⇒ Off When vehicle speed increases to (62.5 mph (100 km/h) or ambient
temperature decreases to 25 °C (77 °F)
For engine cooling during normal running:
⇒ On 100 °C (212 °F)
⇒ Off 94.5 °C (202 °F)
For engine cooling at ignition off (to counteract heat
soak):
⇒ On If, within 10 seconds of ignition off, intake air temperature is 60 °C (140
°F) or more and engine coolant temperature is 110 °C (230 °F) or more
⇒ Off After 10 minutes or if engine coolant temperature decreases to 100 °C
(212 °F)
Coolant pump Centrifugal impeller, belt driven from crankshaft
Coolant pump drive ratio 1.293 : 1
Coolant pump output at 1000 rev/min 10 litres/min (2.64 US galls/min) at 0.7 bar (10 lbf.in
2)
Thermostat Waxstat with pressure relief valve
Thermostat operating temperature:
⇒ Initial opening 82 °C (179 °F)
⇒ Fully open 96 °C (204 °F)
Expansion tank cap relief valve - system operating
pressure1.4 bar (20 lbf.in
2)