1999 LAND ROVER DISCOVERY ignition

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.

ENGINE MANAGEMENT SYSTEM - V8
18-2-64 DESCRIPTION AND OPERATION
Cruise control master switch
The cruise control master switch switches the system on and off. When the cruise control master switch is on, an
LED within the switch illuminates. If the cruise control master switch is off, cruise control will not operate. The switch
provides a 12 Volt feed to the cruise control ECU.
The cruise control master switch is located on the instrument panel near the steering column.
Input/Output
The input from the cruise control master switch to the cruise control ECU is either a 12 Volts ignition feed or an open
circuit. 12 Volts indicates that the cruise control master switch is on and the system can be activated. An open circuit
indicates that the cruise control master switch is off and cruise control cannot be activated.
TestBook will not communicate with the cruise control ECU if the cruise control master switch is off.

ENGINE MANAGEMENT SYSTEM - V8
DESCRIPTION AND OPERATION 18-2-67
SET+/RES switches
The cruise control system uses two steering wheel switches labelled SET+ and RES.
The SET+ switch performs the set speed, tap up and accelerator functions. The RES switch performs the resume and
suspend functions.
With the cruise control master switch on and the vehicle in the cruise control operating speed range, one press of the
SET+ switch stores a speed value in the cruise control ECU. If the switch is pressed and held while the vehicle is
under cruise control operation, speed increases until the switch is released. At this point the cruise control ECU stores
the new speed value. If the switch is tapped (held down for less than 0.5 second) the cruise control ECU increases
vehicle speed by 1 mph (1.5 km/h).
If the RES switch is pressed while the systems is inactive (no stored values) the system will not respond. If there is
a stored value in the cruise control ECU memory and the switch is pressed, the cruise control system operates and
holds the vehicle at the stored road speed. If the cruise control system is active and the RES switch is depressed,
the cruise control ECU deactivates cruise operation but maintains the current set speed value.
Input/Output
The input from the SET+ switch to the cruise control ECU is either 12 Volts or an open circuit.
The input from the RES switch to the cruise control ECU is either 12 Volts or an open circuit.
The following diagnostic information is available through TestBook:
lThe state of operator switch SET+.
lThe state of operator switch RES.
ECU operating parameters (connector connected)
Pin No. Condition Volts Ohms
4 Ignition in position II, SET+ switch
releasedMore than 10,000
4 Ignition in position II, SET+ switch
pressed12
2 Ignition in position II, RES switch
releasedMore than 10,000
2 Ignition in position II, RES switch
pressed12

ENGINE MANAGEMENT SYSTEM - V8
18-2-68 DESCRIPTION AND OPERATION
Brake pedal switch
The cruise control ECU has two inputs from the brake pedal switch that determine the position of the brake pedal.
One input comes through the BCU and is low when the brake pedal is not pressed. The second input comes directly
from the brake pedal switch. This input is high when the brake pedal is not pressed. On vehicles with a manual
gearbox, the input from the clutch pedal switch to the cruise control ECU is connected in series with the direct signal
from the brake pedal switch.
If the cruise control ECU receives a changed signal from either source, it deactivates cruise control, removing power
to the vacuum pump and activating the vacuum control valve releasing all vacuum in the system.
The brake pedal switch also provides the signal to illuminate the brake lamps and the brake input to the SLABS ECU.
Input/Output
With the brake pedal and the clutch pedal in the rest position, the cruise control ECU receives 12 Volts.
With the brake pedal pressed, the cruise control ECU receives 0 Volts and a low voltage logic signal from the BCU.
NOTE: If the clutch pedal is pressed, 0 Volts are present at the cruise control ECU irrespective of brake pedal position.
ECU operating parameters (connector connected)
Pin No. Condition Volts Ohms
1 Ignition in position II, brake pedal
released, clutch pedal released12
1 Ignition in position II, brake pedal
pressed, clutch pedal releasedMore than 10,000
1 Ignition in position II, brake pedal
released, clutch pedal pressedMore than 10,000

ENGINE MANAGEMENT SYSTEM - V8
18-2-74 DESCRIPTION AND OPERATION
Operation - cruise control
Cruise control activation
Cruise control is a passive system. The driver must activate it. Switching on the cruise control master switch located
on the instrument panel activates cruise control. An LED in the switch illuminates, indicating cruise control is
available. The driver must accelerate the vehicle to the desired speed using the accelerator pedal. When the desired
speed is reached, pressing the SET+ switch activates cruise control. Cruise control will only activate if the following
conditions are met:
lVehicle speed is between 28 - 125 mph (45 - 200 km/h).
lThe brake pedal is not pressed.
lThe clutch pedal is not pressed (manual gearbox only).
lThe gearbox is not in park, reverse or neutral (automatic gearbox only).
Function
The cruise control ECU receives the set signal and determines the vehicle speed provided by the SLABS ECU. The
cruise control ECU activates the vacuum pump assembly to move the pneumatic actuator and the linkage to the
throttle disc to maintain set road speed. It does this by controlling the vacuum to the pneumatic actuator.
Cruise control cancellation
Cancelling cruise control enables the driver to regain control of the vehicle speed by using the accelerator pedal.
Cruise control is cancelled if any of the following conditions occur:
lThe brake pedal is pressed.
lThe RES switch button is pressed.
lThe clutch pedal is pressed (manual gearbox only).
lThe cruise control master switch is turned off.
lThe gearbox is placed in park, neutral, or reverse (automatic gearbox only).
Function
The cruise control ECU cancels cruise control operation by opening a vacuum control valve in the vacuum pump
assembly. This releases the throttle linkage from the control of the pneumatic actuator and returns it to the control of
the accelerator pedal.
The set speed will be stored in the cruise control ECU unless:
lThe cruise control master switch is turned off.
lThe ignition switch is turned off.
If cruise control is deactivated using either of the above methods, the set speed will be erased from the memory of
the cruise control ECU.
Cruise control resume
Cruise control can be resumed at the previously set speed, provided the set speed has not been erased from the
cruise control ECU memory as described above. To resume cruise control operation to the previously set speed,
depress the RES switch once when the following conditions are met:
lA set speed is stored in the cruise control ECU.
lVehicle speed is between 28 - 125 mph (45 - 200 km/h).
lThe brake pedal is not pressed.
lThe clutch pedal is not pressed (manual gearbox only).
lThe gearbox is not in park, reverse or neutral (automatic gearbox only).
Function
The cruise control ECU activates the vacuum pump assembly to move the pneumatic actuator. This moves the
throttle to the set speed by adjusting the position of the throttle disc.

ENGINE MANAGEMENT SYSTEM - V8
18-2-80 REPAIRS
Coil - ignition
$% 18.20.45
Remove
1.Remove upper inlet manifold assembly.

+ MANIFOLDS AND EXHAUST
SYSTEMS - V8, REPAIRS, Gasket - inlet
manifold - upper - Without Secondary Air
Injection.
2.Disconnect multiplugs from ignition coils.
3.Release ht leads from rocker covers and
disconnect ht leads from spark plugs.
4.Carefully manoeuvre ignition coil assembly
from between engine and bulkhead. 5.Noting their fitted position disconnect ht leads
from ignition coil.
6.Remove 3 screws securing ignition coil to
support bracket and remove coils.
Refit
1.Position ignition coil to support bracket, fit and
tighten screws.
2.Connect ht leads to ignition coil ensuring they
are in the correct position.
3.Carefully position ignition coil assembly
between engine and bulkhead.
4.Connect ht leads to spark plugs and secure ht
leads to rocker covers.
5.Connect multiplugs to ignition coils.
6.Fit upper inlet manifold assembly.

+ MANIFOLDS AND EXHAUST
SYSTEMS - V8, REPAIRS, Gasket - inlet
manifold - upper - Without Secondary Air
Injection.

ENGINE MANAGEMENT SYSTEM - V8
18-2-92 REPAIRS
Valve - idle air control (IACV)
$% 19.22.54
Remove
1.Disconnect multiplug from IACV.
2.Loosen 2 clips securing air hoses and release
hoses.
3.Remove 2 screws securing IACV to inlet
manifold.
4.Collect clamps and remove IACV.
Refit
1.Position IACV to inlet manifold, locate clamps,
fit screws and tighten to 8 Nm (6 lbf.ft).
2.Position air hoses to IACV and secure clips.
3.Connect multiplug to IACV.
Injectors
$% 19.60.12
Remove
1.Remove upper manifold.

+ MANIFOLDS AND EXHAUST
SYSTEMS - V8, REPAIRS, Gasket - inlet
manifold - upper - Without Secondary Air
Injection.
2.Carefully manoeuvre ignition coil assembly
from between inlet manifold and bulkhead.
3.Position absorbent cloth beneath fuel pipe to
catch spillage.
4.Disconnect fuel feed hose from fuel rail
CAUTION: Always fit plugs to open
connections to prevent contamination.
5.Release injector harness from fuel rail and
disconnect injector multiplugs.

ENGINE MANAGEMENT SYSTEM - V8
REPAIRS 18-2-93
6.Remove 4 bolts securing fuel rail to inlet
manifold.
7.Release injectors from inlet manifold and
remove fuel rail and injectors.
8.Release spring clips securing injectors to fuel
rail and remove fuel injectors.
9.Remove and discard 2 'O' rings from each
injector.
10.Fit protective caps to each end of injectors. Refit
1.Clean injectors and recesses in fuel rail and
inlet manifold.
2.Lubricate new 'O' rings with silicone grease
and fit to each end of injectors.
3.Fit injectors to fuel rail and secure with spring
clips.
4.Position fuel rail assembly and push-fit each
injector into inlet manifold.
5.Fit bolts securing fuel rail to inlet manifold and
tighten to 9 Nm (7 lbf.ft).
6.Connect fuel feed hose to fuel rail.
7.Connect injector harness multiplugs and
secure to fuel rail.
8.Carefully position ignition coil assembly
between inlet manifold and bulkhead.
9.Fit upper manifold.

+ MANIFOLDS AND EXHAUST
SYSTEMS - V8, REPAIRS, Gasket - inlet
manifold - upper - Without Secondary Air
Injection.