1999 LAND ROVER DISCOVERY check engine

ENGINE MANAGEMENT SYSTEM - V8
DESCRIPTION AND OPERATION 18-2-59
⇒ Drive cycle C:
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).
7Cruise at 60 mph (100 km/h) for 8 minutes.
8Cruise at 50 mph (80 km/h) for 3 minutes.
9Allow engine to idle for 3 minutes.
10Connect TestBook and with the engine still running, check for fault codes.
NOTE: The following areas have an associated readiness test which must be flagged as complete, before a problem
resolution can be verified:
lcatalytic converter fault;
lEvaporative loss system fault;
lHO
2 sensor fault;
lHO
2 sensor heater fault.
When carrying out a drive cycle C to determine a fault in any of the above areas, select the readiness test icon to
verify that the test has been flagged as complete.
⇒ Drive cycle D:
1Switch ignition on for 30 seconds.
2Ensure engine coolant temperature is less than 35°C (95°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).
7Cruise at 60 mph (100 km/h) for 5 minutes.
8Cruise at 50 mph (80 km/h) for 5 minutes.
9Cruise at 35 mph (60 km/h) for 5 minutes.
10Allow engine to idle for 2 minutes.
11Connect TestBook and check for fault codes.
⇒ Drive cycle E:
1Ensure fuel tank is at least a quarter full.
2Carry out Drive Cycle A.
3Switch off ignition.
4Leave vehicle undisturbed for 20 minutes.
5Switch on ignition.
6Connect TestBook and check for fault codes.

FUEL DELIVERY SYSTEM - V8
DESCRIPTION AND OPERATION 19-2-7
Fuel pump
The fuel pump assembly comprises a top cover which locates the fuel pressure regulator, electrical connector and
fuel pipe coupling. The top cover is attached to a plastic cup shaped housing by two metal springs. The housing
locates the pump and the fuel gauge sender unit.
The lower part of the housing is the swirl pot, which maintains a constant fuel level at the fuel pick-up. A feed pipe
from the pump to the coupling connection and a return pipe from the regulator connect between the top cover and the
housing.
A coarse filter is attached to the base of the housing and prevents the ingress of large contaminants into the swirl pot.
A gauze filter prevents particles entering the fuel pump.
Surrounding the pump is a large fine paper filter element which further protects the fuel pressure regulator, engine
and injectors from particulate contamination. The paper filter is not a serviceable item and removes the requirement
for an external in-line filter.
A non-return valve is located in the base of the housing. When the fuel tank is full, fuel pressure keeps the valve lifted
from its seat allowing fuel to flow into the swirl pot. As the tank level reduces, the fuel pressure in the tank reduces
causing the valve to close. When the valve is closed fuel is retained in the swirl pot, ensuring that the swirl pot remains
full and maintains a constant supply to the fuel pump.
A four pin electrical connector is located on the top cover of the pump and provides power feed and return for fuel
pump and fuel gauge rotary potentiometer operation. A single quick release coupling connects the fuel feed pipe to
the outer top surface of the pump.
Two metal springs are attached to the top cover and the housing of the pump. When the pump is installed it seats on
the lower surface inside the tank. The springs exert a downward pressure on the pump and ensure that the pump is
located positively at the bottom of the fuel tank.
The fuel pump has a maximum current draw of 6.5 A at 12.5 V.
On NAS vehicles with vacuum type EVAP system leak detection capability only, the fuel pump top cover is fitted with
an On Board Diagnostics (OBD) pressure sensor. This sensor has a three pin electrical connector which provides a
connection between the sensor and the ECM. The sensor is sealed in the top cover with an 'O' ring and secured with
a clip. The sensor monitors tank pressure during OBD tests of the fuel evaporation system integrity. A hose is
connected to the sensor and is routed across the top of the fuel tank and terminates at the top of the fuel filler tube.
The pipe is open to atmosphere and provides atmospheric pressure for the sensor operation.

+ ENGINE MANAGEMENT SYSTEM - V8, DESCRIPTION AND OPERATION, Description - engine
management.
Fuel pressure regulator
The fuel pressure regulator is located in the underside of the top cover. The regulator is sealed with two 'O' rings and
retained with a clip.
The regulator is connected to the fuel feed pipe at the top of the pump housing and maintains the fuel pump delivery
pressure to 3.5 bar (50 lbf.in
2). When the fuel delivery pressure exceeds 3.5 bar (50 lbf.in2), the regulator opens and
relieves excess pressure back to the swirl pot via a return pipe. The regulator ensures that the fuel rails and injectors
are supplied with a constant pressure.
The fuel pump delivery pressure and pressure regulator operating pressure can be checked using a Schraeder type
valve located at the rear of the engine on the fuel rail. The valve allows the pump delivery pressure to be measured
using a suitable gauge and an adaptor and hose which are special tools.

FUEL DELIVERY SYSTEM - V8
DESCRIPTION AND OPERATION 19-2-9
Injectors
1'O' ring 2 off
2Electrical connector
3Steel housing
4Filter strainer
5Spring6Valve needle and armature
7Valve seat/spray orifice
8Plastic housing
9Solenoid winding
An injector for each cylinder is mounted externally in the lower inlet manifold on the engine. The injector protrudes
into the inlet manifold tract, where it releases a controlled delivery of fuel into the manifold air inlet.
Each injector is sealed to the fuel rail and the inlet manifold with 'O' rings. Spring clips retain each injector to the fuel
rail and the attachment of the fuel rail clamps the injectors in the lower manifold.
The injector housing is manufactured from plastic which encapsulates a high-alloy steel housing. The steel housing
contains all components which come into contact with fuel. The plastic housing also provides the attachment for the
engine harness connector for the injector. A solenoid is located between the two housings and moves a valve needle
via an armature. The valve needle seats on a valve seat which incorporates a spray orifice plate. A filter strainer is
fitted at the connection with the fuel rail to remove any particulate matter from the fuel before it enters the injector.
When the ECM energises the solenoid, the armature moves lifting the valve needle off its seat. This allows
pressurised fuel from the fuel rail to pass through the injector housing and needle to the spray orifice. The spray orifice
controls the spray shape and fuel metering. When the solenoid is de-energised, the valve needle returns to the valve
seat, aided by a spring, closing off the injection of fuel into the inlet.
Each injector receives a battery supply voltage via a fuse in the engine compartment fusebox. The fuel delivery timing
is controlled by the ECM, which, at a precisely timed interval, provides a ground path for the injector. The completion
of the ground path operates the injector to allow fuel at pump pressure to be delivered from the fuel rail to the injector
nozzle. Each injector sprays a finely atomized spray of fuel into the inlet, where it is mixed with the intake air prior to
combustion.

+ ENGINE MANAGEMENT SYSTEM - V8, DESCRIPTION AND OPERATION, Description - engine
management.
Faults for each injector are stored in the ECM and can be retrieved using TestBook. Each injector can be checked
across the two connector pins. For a correctly functioning injector a resistance of between 13.8 and 15.2 ohms at a
temperature of 20°C (65°F) should be read across the pins.

COOLING SYSTEM - V8
ADJUSTMENTS 26-2-13
ADJUST ME NTS
Drain and refill
$% 26.10.01
WARNING: Since injury such as scalding could
be caused by escaping steam or coolant, do not
remove the filler cap from the coolant expansion
tank while the system is hot.
Drain
1.Visually check engine and cooling system for
signs of coolant leaks.
2.Examine hoses for signs of cracking, distortion
and security of connections.
3.Position drain tray to collect coolant.
4.Remove expansion tank filler cap.
LH side
RH side
5.Remove drain plugs from LH and RH sides of
cylinder block and allow cooling system to
drain.6.Disconnect bottom hose from radiator and
allow cooling system to drain.
7.Disconnect top hose from thermostat and
position open end of hose below level of
coolant pump inlet, to allow coolant to drain
from the system.
Refill
1.Flush system with water under low pressure.
Do not use water under high pressure as it
could damage the radiator.
2.Apply Loctite 577 to cylinder block drain
plugs.Fit drain plugs to cylinder block and
tighten to 30 Nm (22 lbf.ft).
3.Connect bottom hose to radiator and top hose
to thermostat housing. Secure with hose clips.
4.Prepare coolant to required concentration.

+ CAPACITIES, FLUIDS,
LUBRICANTS AND SEALANTS, Anti-Freeze
Concentration.

COOLING SYSTEM - V8
26-2-14 ADJUSTMENTS
5.Release top hose from retaining lugs on the fan
cowl, leaving the hose to rest on the lugs.
6.Remove bleed screw from top hose.
l'A' From 03 MY
l'B' Up to 03 MY
7.Unclip the bleed hose from the battery box.
8.Remove expansion tank from its mounting
bracket. Slowly fill the expansion tank with
coolant, approx. 4 litres (7 pt).
9.Raise the expansion tank approx. 20 cm (8 in)
vertically, coolant will drain into the system.
10.Refill the coolant expansion tank until a steady
flow of coolant is emitted from the bleed hole.
11.Fit the bleed screw then, with the expansion
tank still raised, continue filling the system until
the coolant level reaches the base of the
expansion tank filler neck.
12.Fit expansion tank filler cap, fit the expansion
tank to its mountings and clip the bleed hose to
the battery box.
13.Refit the top hose into its lugs on the fan cowl.
14.Start and run engine until normal operating
temperature is reached, and check for leaks.
15.Switch off engine and allow to cool.
16.Check for leaks and top-up coolant to cold level
mark on expansion tank

MANIFOLDS AND EXHAUST SYSTEMS - V8
REPAIRS 30-2-13
20.Remove inlet manifold gasket.
21.Remove gasket seals.
Refit
1.Clean all traces of sealant from cylinder head
and cylinder block notches.
2.Clean mating faces of cylinder block, cylinder
head and inlet manifold.
3.Apply sealant, Part No. STC 50550 to cylinder
head and cylinder block notches.
4.Fit new gasket seals, ensuring ends engage
correctly in notches.
5.Fit new inlet manifold gasket.
6.Position gasket clamps and fit bolts, but do not
tighten at this stage.
7.Position inlet manifold to engine. Fit manifold
bolts and, working in the sequence shown,
tighten bolts initially to 10 Nm (7 lbf.ft) then to
51 Nm (38 lbf.ft).
8.Tighten gasket clamp bolts to 18 Nm (13 lbf.ft).
9.Connect fuel pipe.
10.Clean top hose outlet pipe mating faces.
11.Fit new 'O' ring to outlet pipe.
12.Position outlet pipe, fit bolts and tighten to 22
Nm (16 lbf.ft).
13.Position alternator, fit bolts and tighten to 45
Nm (33 lbf.ft).
14.Position PAS pump to auxiliary housing and
locate housing on engine. Fit bolts and tighten
to 40 Nm (30 lbf.ft).15.Fit and tighten auxiliary housing nut to 10 Nm (7
lbf.ft).
16.Fit bolts securing PAS pump and tighten to 22
Nm (16 lbf.ft).
17.Position oil cooling pipe bracket fit bolt and
tighten to 22 Nm (16 lbf.ft).
18.Fit and tighten PAS pump high pressure pipe.
19.Position jockey pulley and tighten bolt to 50 Nm
(37 lbf.ft).
20.Clean PAS pump pulley mating faces.
21.Position PAS pump pulley, fit bolts and tighten
to 22 Nm (16 lbf.ft).
22.Clean ACE pump dowels and dowel holes.
23.Position ACE pump, fit bolts and tighten to 22
Nm (16 lbf.ft).
24.Fit auxiliary drive belt.

+ CHARGING AND STARTING,
REPAIRS, Belt - auxiliary drive.
25.Secure injector harness and connect injector
multiplugs.
26.Position top hose and secure clips.
27.Fit rocker covers.
l

+ ENGINE - V8, REPAIRS, Gasket
- rocker cover - LH.
l

+ ENGINE - V8, REPAIRS, Gasket
- rocker cover - RH.
28.Check and top up PAS fluid

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.
With time, the components in a gearbox wear and the duration of the gear shifts tends to increase, which has an
adverse effect on the brake clutches. To counteract this, the EAT ECU applies a pressure adaptation to each shift.
To calculate the adaptations, the EAT ECU monitors the pressure modulation used, and time taken, for each shift. If
a subsequent shift of the same type, in terms of throttle position and engine speed, has a longer duration, the EAT
ECU stores an adaptation for that type of shift in a volatile memory. The adaptation is then included in future pressure
calculations for that type of shift, to restore shift duration to the nominal.

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.