stop start LAND ROVER DISCOVERY 1999 Workshop Manual

MAINTENANCE
10-18 PROCEDURES
Automatic gearbox
WARNING: Avoid excessive skin contact with
mineral oil. Mineral oils remove the natural fats
from the skin, leading to dryness, irritation and
dermatitis.
Replace oil filter
1.Replace oil filter.

+ AUTOMATIC GEARBOX - ZF4HP22
- 24, REPAIRS, Filter - oil.
Replace oil
1. Ensure that gearbox is cool. Apply
handbrake and securely chock front and rear
wheels.
2.Place a suitable container beneath gearbox.
3.Clean area around oil filler/level and drain
plugs.
4.Remove oil drain plug, remove and discard
sealing washer.
5.Allow oil to drain.
6.Fit new sealing washer to oil drain plug.
7.Fit automatic gearbox drain plug and tighten to
15 Nm (11 lbf.ft).
8.Remove oil filler/level plug, remove and discard
sealing washer.
9.Fill gearbox with recommended oil to bottom of
oil level/filler plug hole.

+ CAPACITIES, FLUIDS,
LUBRICANTS AND SEALANTS,
Lubrication.
10.Select 'P' (Park).
11.Ensure handbrake is applied.
12.Start engine and allow it to idle.
13.Apply footbrake. 14.Move selector lever through all gear positions,
while continuing to fill the gearbox. Select 'P'
(Park).
15.With engine idling, continue filling gearbox until
a 2 mm bead of oil runs from oil filler/level plug
hole.
16.Fit new sealing washer to automatic gearbox
filler/level plug, fit plug and tighten to 30 Nm (22
l b f . f t ) .
17.Stop engine.
18.Remove all traces of oil from gearbox casing.

ENGINE - V8
REPAIRS 12-2-35
Filter - oil
$% 12.60.04
Remove
1.Clean area around filter head and place a
container beneath engine.
2.Using a strap wrench, unscrew and discard
filter.
Refit
1.Clean mating face of filter head.
2.Lubricate sealing ring of new filter with clean
engine oil.
3.Fit filter and tighten by hand until it seats then
tighten a further half turn.
4.Start and run engine to check for leaks.
5.Stop engine, wait a few minutes, then check oil
level.
6.Top up engine oil.
Strainer - oil pick-up
$% 12.60.20
Remove
1.Remove sump gasket.

+ ENGINE - V8, REPAIRS, Gasket -
sump.
2.Remove 2 bolts and one nut securing oil pick-
up strainer.
3.Remove oil pick-up strainer.
4.Collect spacer from stud.
5.Remove and discard 'O'ring.
Refit
1.Clean oil pick up strainer and 'O' ring recess.
2.Lubricate and fit new 'O' ring.
3.Locate spacer on stud.
4.Position oil pick-up strainer, fit bolts and tighten
to 10 Nm (8 lbf.ft). Fit nut and tighten to 22 Nm
(16 lbf.ft).
5.Fit new sump gasket.

+ ENGINE - V8, REPAIRS, Gasket -
sump.

EMISSION CONTROL - V8
17-2-26 DESCRIPTION AND OPERATION
Secondary Air Injection System
The secondary air injection (SAI) system comprises the following components:
lSecondary air injection pump
lSAI vacuum solenoid valve
lSAI control valves (2 off, 1 for each bank of cylinders)
lSAI pump relay
lVacuum reservoir
lVacuum harness and pipes
The secondary air injection system is used to limit the emission of carbon monoxide (CO) and hydrocarbons (HCs)
that are prevalent in the exhaust during cold starting of a spark ignition engine. The concentration of hydrocarbons
experienced during cold starting at low temperatures are particularly high until the engine and catalytic converter
reach normal operating temperature. The lower the cold start temperature, the greater the prevalence of
hydrocarbons emitted from the engine.
There are several reasons for the increase of HC emissions at low cold start temperatures, including the tendency for
fuel to be deposited on the cylinder walls, which is then displaced during the piston cycle and expunged during the
exhaust stroke. As the engine warms up through operation, the cylinder walls no longer retain a film of fuel and most
of the hydrocarbons will be burnt off during the combustion process.
The SAI pump is used to provide a supply of air into the exhaust ports in the cylinder head, onto the back of the
exhaust valves, during the cold start period. The hot unburnt fuel particles leaving the combustion chamber mix with
the air injected into the exhaust ports and immediately combust. This subsequent combustion of the unburnt and
partially burnt CO and HC particles help to reduce the emission of these pollutants from the exhaust system. The
additional heat generated in the exhaust manifold also provides rapid heating of the exhaust system catalytic
converters. The additional oxygen which is delivered to the catalytic converters also generate an exothermic reaction
which causes the catalytic converters to 'light off' quickly.
The catalytic converters only start to provide effective treatment of emission pollutants when they reach an operating
temperature of approximately 250°C (482°F) and need to be between temperatures of 400°C (752°F) and 800°C
(1472°F) for optimum efficiency. Consequently, the heat produced by the secondary air injection “afterburning”,
reduces the time delay before the catalysts reach an efficient operating temperature.
The ECM checks the engine coolant temperature when the engine is started in addition to the elapsed time since the
engine was last started. The engine coolant temperature must be below 55°C (131°F) for the SAI pump to run.
NOTE: The ambient air temperature must also be above 8
°C (46°F) for the SAI pump to run.
Also, depending on the long term 'modelled' ambient temperature determined by the ECM, the minimum elapsed time
required since the last engine start can be up to 8.25 hours. The period of time that the SAI pump runs for depends
on the starting temperature of the engine and varies from approximately 96 seconds at 8°C (46°F) to 30 seconds at
55°C (131°F).
Air from the SAI pump is supplied to the SAI control valves via pipework and an intermediate T-piece which splits the
air flow evenly to each bank.
At the same time the secondary air pump is started, the ECM operates a SAI vacuum solenoid valve, which opens to
allow vacuum from the reservoir to be applied to the vacuum operated SAI control valves on each side of the engine.
When the vacuum is applied to the SAI control valves, they open simultaneously to allow the air from the SAI pump
through to the exhaust ports. Secondary air is injected into the inner most exhaust ports on each bank.
When the ECM breaks the ground circuit to de-energise the SAI vacuum solenoid valve, the vacuum supply to the
SAI control valves is cut off and the valves close to prevent further air being injected into the exhaust manifold. At the
same time as the SAI vacuum solenoid valve is closed, the ECM opens the ground circuit to the SAI pump relay, to
stop the SAI pump.
A vacuum reservoir is included in the vacuum line between the intake manifold and the SAI vacuum solenoid valve.
This prevents changes in vacuum pressure from the intake manifold being passed on to cause fluctuations of the
secondary air injection solenoid valve. The vacuum reservoir contains a one way valve and ensures a constant
vacuum is available for the SAI vacuum solenoid valve operation. This is particularly important when the vehicle is at
high altitude.

EMISSION CONTROL - V8
DESCRIPTION AND OPERATION 17-2-43
Secondary Air Injection System
Operation
When the engine is started, the engine control module checks the engine coolant temperature and if it is below 55°
C, the ECM grounds the electrical connection to the coil of the secondary air injection (SAI) pump relay.
A 12V battery supply is fed to the inertia switch via fuse 13 in the engine compartment fusebox. When the inertia
switch contacts are closed, the feed passes through the switch and is connected to the coil of the Main relay. An earth
connection from the Main relay coil is connected to the ECM. When the ECM completes the earth path, the coil
energises and closes the contacts of the Main relay.
The Main and Secondary Air Injection (SAI) pump relays are located in the engine compartment fusebox. When the
contacts of the Main relay are closed, a 12V battery supply is fed to the coil of the SAI pump relay. An earth connection
from the coil of the SAI pump relay is connected to the ECM. When the ECM completes the earth path, the coil
energises and closes the contacts of the SAI pump relay to supply 12V to the SAI pump via fusible link 2 in the engine
compartment fusebox. The SAI pump starts to operate, and will continue to do so until the ECM switches off the earth
connection to the coil of the SAI pump relay.
The SAI pump remains operational for a period determined by the ECM and depends on the starting temperature of
the engine, or for a maximum operation period determined by the ECM if the target engine coolant temperature has
not been reached in the usual time.
When the contacts of the main relay are closed, a 12V battery supply is fed to the SAI solenoid valve via Fuse 2 in
the engine compartment fusebox.
The ECM grounds the electrical connection to the SAI vacuum solenoid valve at the same time as it switches on the
SAI pump motor. When the SAI vacuum solenoid valve is energised, a vacuum is provided to the operation control
ports on both of the vacuum operated SAI control valves at the exhaust manifolds. The control vacuum is sourced
from the intake manifold depression and routed to the SAI control valves via a vacuum reservoir and the SAI vacuum
solenoid valve.
The vacuum reservoir is included in the vacuum supply circuit to prevent vacuum fluctuations caused by changes in
the intake manifold depression affecting the operation of the SAI control valves.
When a vacuum is applied to the control ports of the SAI control valves, the valves open to allow pressurised air from
the SAI pump to pass through to the exhaust ports in the cylinder heads for combustion.
When the ECM has determined that the SAI pump has operated for the desired duration, it switches off the earth paths
to the SAI pump relay and the SAI vacuum solenoid valve. With the SAI vacuum solenoid valve de-energised, the
valve closes, cutting off the vacuum supply to the SAI control valves. The SAI control valves close immediately and
completely to prevent any further pressurised air from the SAI pump entering the exhaust manifolds.
The engine coolant temperature sensor incurs a time lag in respect of detecting a change in temperature and the SAI
pump automatically enters a 'soak period' between operations to prevent the SAI pump overheating. The ECM also
compares the switch off and start up temperatures, to determine whether it is necessary to operate the SAI pump.
This prevents the pump running repeatedly and overheating on repeat starts.
Other factors which may prevent or stop SAI pump operation include the prevailing engine speed / load conditions.

ENGINE MANAGEMENT SYSTEM - V8
18-2-8 DESCRIPTION AND OPERATION
Engine Control Module (ECM)
The engine control module (ECM) is located on the RH side A post below the face panel inside the vehicle. It has a
cast aluminium case and is mounted on a bracket. The ECM has 5 independent connectors totalling 134 pins.
The ECM is available in 4 variants:
lNAS.
lNAS low emission vehicles.
lUK/ Europe/ Japan/ Australia.
lROW/ Gulf.
The ECM uses a 'flash' electronic erasable programmable read only memory (EEPROM). This enables the ECM to
be externally configured, to ensure that the ECM can be updated with any new information, this also allows the ECM
to be configured with market specific data. TestBook must be used to configure replacement ECM's. The ECM can
be reprogrammed, using TestBook/T4, with new engine tunes up to 16 times to meet changing specifications and
legislation. The current engine tune data can be accessed and read using TestBook/T4.
The ECM memorises the positions of the crankshaft and the camshaft when the engine has stopped via the CKP and
CMP sensors. This allows immediate sequential fuel injection and ignition timing during cranking. This information is
lost if battery voltage is too low (i.e. flat battery). So the facility will be disabled for the first engine start.
Input/Output
The ECM has various sensors fitted to the engine to allow it to monitor engine condition. The ECM processes these
signals and decides what actions to carry out to maintain optimum engine operation by comparing the information
from these signals to mapped data within its memory.
Connector 1 (C0634): This connector contains 9 pins and is used primarily for ECM power input and earth. The ECM
requires a permanent battery supply, if this permanent feed is lost i.e. the battery discharges or is disconnected the
ECM will lose its adapted values and its Diagnostic Trouble Codes (DTC). These adapted values are a vital part of
the engine management's rolling adaptive strategy. Without an adaptive strategy, driveability, performance, emission
control, and fuel consumption are adversely affected. The ECM can be damaged by high voltage inputs, so care must
be taken when removing and replacing the ECM.

ENGINE MANAGEMENT SYSTEM - V8
DESCRIPTION AND OPERATION 18-2-51
Conditions
The ECM calculates ignition timing using input from the following:
lCKP sensor.
lKnock sensors (KS).
lMAF sensor.
lTP sensor (idle only).
lECT sensor.
Function
At engine start up, the ECM sets ignition timing dependent on ECT information and starting rev/min from the CKP. As
the running characteristics of the engine change, the ignition timing changes. The ECM compares the CKP signal to
stored values in its memory, and if necessary advances or retards the spark via the ignition coils.
Ignition timing is used by the ECM for knock control.
Knock control
The ECM uses active knock control to prevent possible engine damage due to pre-ignition. This is achieved by
converting engine block noise into a suitable electrical signal that can be processed by the ECM. A major contributing
factor to engine 'knock' is fuel quality, the ECM can function satisfactorily on 91 RON fuel as well as the 95 RON fuel
that it is calibrated for.
Conditions
The ECM knock control system operates as follows:
lHot running engine.
l91 or 95 RON fuel.
Function
The ECM knock control uses two sensors located one between the centre two cylinders of each bank. The knock
sensors consist of piezo ceramic crystals that oscillate to create a voltage signal. During pre-ignition, the frequency
of crystal oscillation increases which alters the signal output to the ECM.
If the knock sensors detect pre-ignition in any of the cylinders, the ECM retards the ignition timing by 3° for that
particular cylinder. If this action stops the engine knock, the ignition timing is restored to its previous figure in
increments of 0.75°. If this action does not stop engine knock then the ECM retards the ignition timing a further 3° up
to a maximum of -15° and then restores it by 0.75° and so on until the engine knock is eliminated.
The ECM also counteracts engine knock at high intake air temperatures by retarding the ignition as above. The ECM
uses the IAT signal to determine air temperature.
Idle speed control
The ECM regulates the engine speed at idling. The ECM uses the idle air control valve (IACV) to compensate for the
idle speed drop that occurs when the engine is placed under greater load than usual. When the throttle is in the rest
position i.e. it has not been pressed, the majority of intake air that the engine consumes comes from the idle air control
valve.
IACV control idle speed
Conditions in which the ECM operates the IACV control idle speed is as follows:
lIf any automatic transmission gears other than P or N are selected.
lIf air conditioning is switched on.
lIf cooling fans are switched on.
lAny electrical loads activated by the driver.
Function
The idle air control valve utilises two coils that use opposing pulse width modulated (PWM) signals to control the
position of a rotary valve. If one of the circuits that supplies the PWM signal fails, the ECM closes down the remaining
signal preventing the idle air control valve from working at its maximum/ minimum setting. If this should occur, the idle
air control valve assumes a default idle position at which the engine idle speed is raised to 1200 rev/min with no load
placed on the engine.

AUTOMATIC GEARBOX - ZF4HP22 - 24
44-18 DESCRIPTION AND OPERATION
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.
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.

STEERING
57-18 ADJUSTMENTS
Hydraulic system - bleed
$% 57.15.02
Bleed
1.Clean PAS fluid reservoir around filler cap and
fluid level indicators.
2.Remove filler cap from PAS fluid reservoir. If
necessary, fill PAS fluid reservoir to upper level
indicator with recommended fluid.

+ CAPACITIES, FLUIDS,
LUBRICANTS AND SEALANTS, Fluids.
CAUTION: Ensure no dirt is allowed to enter
the steering reservoir when the cap is
removed.
3.Start engine and run to normal operating
temperature.
4.Position container to catch fluid spillage from
steering box.
5.With engine at idle speed, and an assistant
turning the steering from lock to lock, loosen
bleed screw on top of steering box. Keep PAS
fluid reservoir topped up and allow all air to
bleed from system. When fluid from bleed
screw is free of air, tighten bleed screw.
CAUTION: Do not hold steering at full lock
for longer than 10 seconds.
6.Stop engine.
7.Clean spilled PAS fluid from steering box and
surrounding area.
CAUTION: Power steering fluid will damage
paint finished surfaces. If spilled,
immediately remove fluid and clean area
with water.
8.Check fluid level in PAS fluid reservoir and fill to
upper level mark. If fluid is aerated, wait until
fluid is free from bubbles.
9.Fit PAS fluid reservoir filler cap.
Steering linkage - centralise
$% 57.35.05
The following procedure assumes that the front
wheel alignment is correctly adjusted.
Adjust
1.Raise front of vehicle, and position the road
wheels at straight ahead.
WARNING: Do not work on or under a
vehicle supported only by a jack. Always
support the vehicle on safety stands.
2.Remove nut securing drag link to drop arm.
Using tool LRT-57-036 break taper joint and
release drag link from drop arm.
3.Fit centralising bolt to steering box and ensure
that front road wheels are in the straight ahead
position.
4.Loosen clamp bolts on drag link.

STEERING
ADJUSTMENTS 57-21
13.Remove bolt from steering box pipe retaining
clip. Leaving the PAS reservoir oil pipe in place,
release pipe retaining clip and PAS cooler pipe
from steering box, discard the seal.
14.Fit tool LRT-57-041 to steering box housing.
15.Fit seal to PAS oil cooler pipe.
16.Fit PAS cooler pipe to LRT-57-041 align the
retaining clip to pipes and tighten bolt to 24 Nm
(18 lbf.ft).
17.Connect test hoses LRT-57-002 to LRT-57-
041 and tighten unions. Ensure all pipes and
fittings are clear of engine rotating parts.18.Hang pressure gauge in a safe position under
bonnet.
19. LHD only: Fit turbocharger intercooler feed
pipe and vacuum connection and fit PAS
reservoir to mounting bracket. Fit air intake
hose to turbocharger and air cleaner and
connect multiplug to MAF sensor. The above
parts must be refitted in order to run the
engine.
20.Fill PAS reservoir, connect battery earth lead.
Start engine and allow air to bleed from PAS
system, by turning steering from lock to lock.
Stop engine and check PAS fluid level.
21.Ensure steering system is free from leaks and
maintain maximum fluid level during test.
22.Open the test valve on LRT-57-001 and start
the engine.
23.With the engine at idle and normal running
temperature, slowly turn the steering wheel and
hold on lock.
24.Note reading on pressure gauge.
25.Repeat pressure check on opposite lock, again
noting the reading on the pressure gauge.
26.The test pressure should be between 21 and 62
bar, (300 to 900 lbf/in
2. Pressure will rise to 62
bar (900 lbf/in2) when held on full lock.
27.With the engine at idle, centralise the steering
wheel. Pressure should read 7 bar (100 lbf/in
2)
or below.
28.Pressure outside the above tolerance indicates
a fault.
29.To determine if fault is in steering pump or
steering rack, close the valve on LRT-57-001
for a maximum of five seconds. Pump damage
may occur if test valve is closed for longer
periods.
30.If the gauge does not register between 75 and
103 bar, (1500 lbf/in
2) (maximum pump
pressure), the pump is faulty.
31.If maximum pump pressure is obtained,
suspect the steering box.
32.On completion, stop engine, disconnect battery
earth lead and syphon fluid from PAS reservoir.
33. LHD only: Disconnect multiplug from MAF
sensor, remove air intake hose clips and move
hose aside.
34. LHD only: Release PAS reservoir from
mounting, for access to turbocharger
intercooler pipe.Remove vacuum hose from
turbocharger intercooler pipe.Release clips and
disconnect intercooler pipe from turbocharger.
35.Remove test equipment from tool LRT-57-041.
36.Remove bolt and clip from steering box.
37.Release PAS cooler pipe from tool LRT-57-041
and discard seal. leaving PAS reservoir oil pipe
in place, release tool LRT-57-041 from
steering box and discard seal.

STEERING
ADJUSTMENTS 57-23
9.Release clips and remove air intake hose from
air cleaner housing.
Note: Pre 03 MY air intake hose illustrated.
10.Discard intake 'O' ring and move intake aside
for access.
11.Loosen union securing high pressure pipe to
PAS pump and release pipe.12.Fit adaptor LRT-57-034A to high pressure port
of PAS pump.
13.Fit adaptor LRT-57-035 to existing high
pressure hose.
14.Fit hose LRT-57-002/3 to each adaptor.
15.Fit pressure gauge LRT-57-005 to test valve
LRT-57-001
16.Connect hoses LRT-57-002/3 to LRT-57-001
and tighten unions.
17.Hang pressure gauge in a safe position under
bonnet.
18.Remove PAS reservoir filler cap, fill to level
indicator and refit cap.
19.Connect battery earth lead.
20.Start engine and allow air to bleed from PAS
system by turning steering from lock to lock.
Stop engine and check PAS fluid level.
21.Ensure steering system and test equipment are
free from leaks.
22.Maintain maximum fluid level during test.
23.Open the test valve on LRT-57-001 and start
the engine.
24.With the engine at idle, slowly turn the steering
wheel and hold on full lock.
25.Note the pressure reading on LRT-57-005.
26.Repeat the pressure check for the opposite full
lock.
27.Test pressure should be between 21 and 62
bar, (300 to 900) psi. Dependant on road
surface.
28.With the engine at idle, centralise the steering
wheel. Pressure should read 7 bar (100 psi) or
below.
29.Pressures outside the above tolerance
indicates a fault.
30.To determine if fault is in steering pump or
steering box, close the valve on LRT-57-001 for
a maximum of 5 seconds. Pump damage may
occur if test valve is closed for longer periods.
31.If gauge does not register between 75 and 103
bar, (1500 psi), (maximum pump pressure), the
pump is faulty.
32.If maximum pump pressure is correct suspect
the steering box.