cruise control LAND ROVER DISCOVERY 1999 Owner's Guide

MANIFOLDS AND EXHAUST SYSTEMS - V8
30-2-20 REPAIRS
34.Release clip and disconnect IACV hose.
35.Remove 6 bolts securing upper manifold and
remove manifold.
36.Collect upper manifold gasket.
Refit
1.Clean upper and lower inlet manifold mating
faces, dowels and dowel holes.
2.Using a new gasket, position upper inlet
manifold. Fit bolts and, working in a diagonal
sequence, tighten to 22 Nm (16 lbf.ft).
3.Connect IACV hose and secure clip.
4.Connect hose to air valve and tighten clip.
5.Secure plug leads to clips.
6.Fit and tighten nuts securing RH air manifold
support bracket.
7.Align air pipe and coil bracket, fit bolts and
tighten to 8 Nm (6 lbf.ft).
8.Tighten 2 lower bolts securing coil bracket to 8
Nm (6 lbf.ft).
9.Fit bonnet seal.
10.Secure engine harness in bulkhead clips.
11.Connect breather hose to manifold and secure
clip.
12.Connect vacuum hose to inlet manifold.
13.Connect brake servo hose to inlet manifold.
14.Connect throttle and cruise control cables.
15.Adjust throttle cable.

+ ENGINE MANAGEMENT SYSTEM -
V8, ADJUSTMENTS, Cable - throttle.16.Adjust cruise control cable.

+ ENGINE MANAGEMENT SYSTEM -
V8, ADJUSTMENTS, Cable - cruise control.
17.Connect coolant hoses to throttle housing and
secure clips.
18.Connect multiplug to TP sensor.
19.Connect breather hose to throttle housing and
secure with clip.
20.Connect multiplug to IACV.
21.Secure purge valve and air control valve to clips
and bracket.
22.Connect purge hose to manifold.
23.Clean air manifold unions.
24.Apply a small amount of engine oil to top of air
manifold union nuts and around air manifold
pipes.
25.Position air manifold and finger tighten both air
manifold union nuts.
CAUTION: Finger tighten union nuts as far
as possible, damage to air manifold pipes or
adaptors may result if this is not done.
26.Tighten both air manifold union nuts to 25 Nm
(18 lbf.ft).
CAUTION: Ensure that air manifold pipes
are not distorted during tightening
operation.
27.Fit nuts securing air manifold support bracket
and tighten to 25 Nm (18 lbf.ft).
28.Connect hose to air valve and tighten clip.
29.Connect vacuum hose to air valve.
30.Fit air intake hose.
31.Connect multiplug to MAF sensor.
32.Secure harness to clip.
33.Connect battery earth lead.
34.Fit battery cover and secure with fixings.
35.Top up cooling system.

+ MAINTENANCE, PROCEDURES,
Cooling system.
36.Fit bonnet.

+ EXTERIOR FITTINGS, REPAIRS,
Bonnet.

STEERING
DESCRIPTION AND OPERATION 57-3
1Air bag module
2Steering wheel and nut
3Horn switch 2 off
4Radio remote control switch (if fitted)
5Column switches
6Lower nacelle
7Column tilt adjustment lever
8Steering column lock
9Ignition switch and harness
10Upper column assembly
11Lower column
12Universal joint 13Bolt
14Bolt
15Intermediate shaft assembly
16Decouple joint
17Rubber coupling and heat shield
18Bolt
19Universal joint
20Shear bolt 2 off
21Rotary coupler
22Upper nacelle
23Cruise control switch (if fitted)

STEERING
57-6 DESCRIPTION AND OPERATION
Tilt adjustment
The column tilt adjuster lever mechanism is located on the LH side of the steering column and allows the upper column
tube, nacelle and steering wheel assemblies to be tilted up or down a maximum of 7.5° or 47 mm (NAS vehicles have
a smaller range of movement than the ROW vehicles).
The pawl of the mechanism is attached to the lower column and is allowed to pivot, a toothed quadrant is fixed to the
upper column tube.
When the lever on the LH side of the steering column is raised the mechanism releases the pawl from the toothed
quadrant, this allows the column to be moved. When the lever is released two return springs pull the pawl into
engagement with the toothed quadrant.
Steering column lock (All except NAS)
The steering column lock houses the ignition switch, ignition illumination light ring, key lock barrel and the alarm
passive coil. The steering lock is attached to the upper column with two shear bolts. The bolts are tightened to a
torque which shears off the heads of the bolts preventing easy removal of the steering lock.
The steering lock operates by a bolt, which emerges when the ignition key is turned to position 'O' and the ignition key
removed. The bolt engages in a lock collar located on the upper shaft in the upper column tube. The lock collar is
attached to the upper shaft by a 'wave form' interference ring. If a high torque is applied via the steering wheel with
the lock engaged, the lock collar will slip on the upper shaft. This prevents damage to the steering lock, yet still
prevents the vehicle from being driven.
Steering column lock (NAS only)
The steering column lock houses the ignition switch, ignition illumination light ring, key lock barrel and the alarm
passive coil. The steering lock is attached to the upper column with two shear bolts. The bolts are tightened to a
torque which shears off the heads of the bolts preventing easy removal of the steering lock.
The steering column lock operates by a bolt, which emerges when the ignition key is turned to position 'O' and the
ignition key removed. The bolt engages in a groove machined into the upper shaft in the column tube.
Steering wheel
The steering wheel comprises a cast centre and wire frame onto which the soft polyurethane foam is moulded. The
steering wheel is located on the upper column shaft by a spline and is secured with a nut. A remote radio control switch
(if fitted) is located on the LH side of the steering wheel, a cruise control switch may be located on the RH side. Horn
switches are located on each side of the centre of the steering wheel and protrude through the airbag module cover.
Both switches are connected by wires to the rotary coupler connector.
Intermediate shaft
One end of the intermediate shaft is attached to the steering column lower shaft by a splined universal joint and a bolt,
the universal joint is part of a rubber coupling assembly. The rubber coupling assembly is covered by a heat shield
and connects to the lower section of the intermediate shaft via a decouple joint. The rubber coupling reduces the
shocks felt by the driver through the steering wheel. A second universal joint on the other end of the intermediate shaft
is held in by a bolt. The universal joint is splined and engages with the splined rotor (input) shaft of the steering box.
The decouple joint consists of a metal plate that has open ended slots, the plate is bolted through the slots into the
other half of the decouple joint. The top half of the decouple joint has a slot that accepts the lower section of the
intermediate shaft. The slotted metal plate clamps the lower section of the intermediate shaft to the top section. An
indicator clip is installed between the slotted metal plate and the top half of the decouple joint.
If the intermediate shaft is compressed in an accident, the slotted metal plate in the decouple joint will disengage if
sufficient force is applied to the front end of the shaft. If the forces involved do not disengage the shaft, the red
indicator clip located in the decouple joint will break off if the shaft moves. The intermediate shaft cannot be repaired
and must be replaced as an assembly if accident damage occurs.

STEERING
57-52 REPAIRS
Steering wheel
$% 57.60.01.30
Remove
1.Remove drivers airbag.

+ RESTRAINT SYSTEMS, REPAIRS,
Airbag module - drivers.
2.Disconnect horn multiplug.
3.Centralise steering wheel with road wheels in
straight ahead position.
4.Restrain steering wheel and loosen self locking
nut securing steering wheel to column.
5.Release steering wheel from column.
6.Remove and discard self locking nut.
7.Remove steering wheel.
8.Attach tape across edge of rotary coupler to
retain correct setting. 9.Release 2 clips securing each horn button to
steering wheel.
10.Remove screw securing horn earth lead to
steering wheel.
11.Disconnect radio and cruise control multiplugs.
12.Remove 2 screws securing radio switches to
steering wheel.
13.Remove radio switches from steering wheel.
14.Remove 2 screws securing cruise control
switches to steering wheel.
15.Remove cruise control switches from steering
wheel.
16.Remove horns from steering wheel.
Refit
1.Fit horn switches to steering wheel and secure
with clips.
2.Fit and tighten screw securing horn earth lead
to steering wheel.
3.Fit cruise control switches to steering wheel
and secure with screws.
4.Fit radio switches to steering wheel and secure
with screws.
5.Connect radio and cruise control multiplugs.
6.Remove tape from rotary coupler.
7.Ensure road wheels are in straight ahead
position and indicator cancelling cam are
aligned horizontally.
8.Fit steering wheel to column.
9.Connect horn multiplug.
10.Fit and tighten new self locking nut securing
steering wheel to column to 43 Nm (32 lbf.ft).
11.Fit drivers airbag.

+ RESTRAINT SYSTEMS, REPAIRS,
Airbag module - drivers.

BRAKES
70-18 DESCRIPTION AND OPERATION
The SLABS ECU continually calculates vehicle speed using the wheel speed inputs from all four ABS sensors. The
calculated vehicle speed is then used as a reference against which individual wheel speeds are monitored for
unacceptable acceleration or deceleration. The ABS sensor inputs are also used by the SLABS ECU to detect vehicle
deceleration rate, vehicle cornering rate and rough terrain.
The engaged forward gear and (on manual gearbox models) the clutch status are computed from the engine data
input, the engine speed input and vehicle speed. Reverse gear status is provided by an input from the reverse lamp
switch (manual gearbox models) or the BCU (automatic gearbox models). On automatic models, the BCU also
provides the neutral selected input.
In addition to controlling the brake related functions, the SLABS ECU:
lControls the operation of the self levelling suspension (SLS) system (where fitted).

+ REAR SUSPENSION, DESCRIPTION AND OPERATION, Description.
lOn V8 models, outputs a rough road signal to the ECM when traversing rough terrain.
lOutputs a vehicle speed signal.
The vehicle speed signal is output to the following systems (where fitted):
lActive Cornering Enhancement.

+ FRONT SUSPENSION, DESCRIPTION AND OPERATION, Description - ACE.
lAir conditioning.

+ AIR CONDITIONING, DESCRIPTION AND OPERATION, Description.
lCruise control.

+ ENGINE MANAGEMENT SYSTEM - Td5, DESCRIPTION AND OPERATION, Description.

+ ENGINE MANAGEMENT SYSTEM - V8, DESCRIPTION AND OPERATION, Description - engine
management.
lEngine management.

+ ENGINE MANAGEMENT SYSTEM - Td5, DESCRIPTION AND OPERATION, Description.

+ ENGINE MANAGEMENT SYSTEM - V8, DESCRIPTION AND OPERATION, Description - engine
management.
lIn-car entertainment.

+ IN CAR ENTERTAINMENT, DESCRIPTION AND OPERATION, Description.
lInstrument pack.

+ INSTRUMENTS, DESCRIPTION AND OPERATION, Description.
5 Front right inlet solenoid valve Output
6 Shuttle valve switches Input
7 Rear left outlet solenoid valve Output
8 Rear left inlet solenoid valve Output
9 Centre differential lock switch Input
10 Rear right outlet solenoid valve Output
11 Rear right inlet solenoid valve Output
12 Brake lamp relay Output
15 Return pump relay Output
C0655
7 Audible warning Output
10 Engine speed Input
Connector and pins not listed are either not used or used by the self levelling suspension system.

+ REAR SUSPENSION, DESCRIPTION AND OPERATION, Description.
Connector/Pin
No.Description Input/Output

PANEL REPAIRS
REPAIRS 77-2-33
Front valance assembly - RH
Remove
1.Disconnect battery eath lead.
2.Remove front bulkhead assembly.

+ PANEL REPAIRS, REPAIRS, Front
bulkhead assembly.
3.Remove engine compartment fusebox and
related wiring.
4.Remove radiator expansion tank from
mountings and position aside.
5. Petrol models: Remove cruise control
actuator mounting bracket.
6. Diesel models: Remove EGR modulator
mounting bracket.
7. RHD models: Remove brake servo.

+ BRAKES, REPAIRS, Servo - brake.
8.Remove brake pipes from valance assembly.
9.Remove RH road wheel.
10.Remove RH front mud flap.
11.Remove insulation pad from engine bulkhead.
12.Remove windscreen side finisher.

+ EXTERIOR FITTINGS, REPAIRS,
Side finisher - windscreen.
Repair
1.Remove existing panel(s), prepare panel joint
faces and install new panel(s) in accordance
with Panel Replacement Procedure. Punch or
drill holes in new panel for plug welding as
shown.Refit
1.Fit windscreen side finisher.

+ EXTERIOR FITTINGS, REPAIRS,
Side finisher - windscreen.
2.Fit insulation pad to engine bulkhead.
3.Fit front mud flap.
4.Fit road wheel and tighten nuts to 140 Nm (103
lbf.ft).
5.Fit brake pipes to valance assembly.
6. RHD models: Fit brake servo.
7. Diesel models: Fit EGR modulator mounting
bracket.
8. Petrol models: Fit cruise control actuator
mounting bracket.
9.Fit radiator expansion tank.
10.Fit fusebox and secure wiring.
11.Fit front bulkhead assembly.

+ PANEL REPAIRS, REPAIRS, Front
bulkhead assembly.
12.Connect battery leads, negative lead last.
M77 1694A

BODY CONTROL UNIT
86-3-16 DESCRIPTION AND OPERATION
Cruise control
The BCU processes several signals used for cruise control:
lWhen the brake pedal is pressed, a low voltage brake lamp signal is sent via the BCU to the cruise control ECU.
lThe gear position switch sends an input via the BCU to the cruise control ECU if the selector lever is in Park,
Neutral or Reverse.
lA voltage supply is fed from the BCU to the cruise control SET+ switch.
lA voltage supply is fed from the BCU to the cruise control RES switch.
On vehicles with automatic transmission, if the BCU receives an input from the gear position switch or the brake pedal
switch, the BCU sends a signal to the cruise control ECU to cancel or inhibit cruise control operation.

+ ENGINE MANAGEMENT SYSTEM - Td5, DESCRIPTION AND OPERATION, Description.

+ ENGINE MANAGEMENT SYSTEM - V8, DESCRIPTION AND OPERATION, Description - cruise control.
Shift interlock (where fitted)
On automatic gearbox models, the BCU and IDM combine with an interlock relay located in the passenger
compartment fuse box to operate a shift interlock solenoid, so that the gear selector lever cannot be moved out of
Park until certain logical conditions have been satisfied. Operation of the interlock may be affected, if the battery
becomes discharged.

+ AUTOMATIC GEARBOX - ZF4HP22 - 24, DESCRIPTION AND OPERATION, Description.
Ignition key interlock (where fitted)
On automatic gearbox models, the ignition key interlock solenoid prevents removal of the ignition key from the ignition
switch when the transmission gear selector is not in the Park position. The logic control operation for this is performed
by the BCU.
Transfer box interlock (where fitted)
On automatic gearbox models, a transfer box interlock solenoid is controlled by the IDM to prevent transfer box shift
lever being moved out of high or low range unless certain conditions have been satisfied. The IDM controls the
operation of the transfer box relay which is located in the passenger compartment fuse box.

+ TRANSFER BOX - LT230SE, DESCRIPTION AND OPERATION, Description.
Gear position switch
A gear position switch is located on the automatic gearbox and is used to inform the BCU of the gear selector lever
position. The BCU has four sensing inputs from the gear position switch contacts W, X, Y, Z, which are used to
determine the gearbox drive status at any particular instance. The BCU gives an output corresponding to the gearbox
status derived from the gear position switch inputs. The logic states defining the gear selector positions are listed in
the table below, where Z1, Z2, Z3 and Z4 represent intermediate states which exist as the selector lever position is
changed:
Gear position Switch contacts
WX Y Z
P (Park) 1 0 0 0
Z11100
R (Reverse) 0 1 0 0
Z11100
N (Neutral) 1 1 1 0
Z21010
D (Drive) 1 0 1 1
Z31111
30111
Z40011
20001
Z40011
10010

BODY CONTROL UNIT
DESCRIPTION AND OPERATION 86-3-31
Gear position indicator illumination
On automatic gearbox models, two variations of illumination for the gear position indicators on the selector lever can
be programmed into the BCU. In option 1, illumination is provided when the ignition is on. In option 2, illumination is
enabled when the ignition is on and the side lamps are off.
Starter relay
The BCU checks the status of the following inputs and internal BCU conditions to determine whether or not to provide
an output to enable the starter relay:
lAutostart inhibit (vehicles with automatic gearbox only).
lSecurity start inhibit (immobilisation check).
lEngine running (link to instrument pack).
lEEPROM locked (internal check).
lIDM and BCU matched.
When the BCU receives a crank signal from the ignition switch, an earth path is completed to the starter relay coil,
provided that the security system has been de-activated. If the ECM has not received a valid unlock/ remobilise signal,
the starter relay will be disengaged and the engine stopped. The BCU also receives an engine running signal from
the instrument pack, so that if the ignition key is turned to the crank position while the engine is running, the starter
motor relay will not be engaged.
If the logic conditions are correct to allow starter operation, the completion of the earth path from the starter relay coil
to the BCU energises the coil and the relay contacts close to supply battery power to the starter motor.
When the ignition switch is released from the crank position, the power supply feed from the ignition switch to the
starter relay coil is interrupted and the relay contacts open to prevent further battery feed to the starter motor.
If a communications link failure is experienced, the BCU will be prevented from detecting the 'engine running'
condition and the BCU will default to assume that the engine is not running.
Cruise control
The Neutral/ Reverse/ Park/ Brake selected output is used by the cruise control system. The BCU checks for the
following inputs:
lIgnition on.
lGearbox state.
lBrake switch activated.
For vehicles with manual transmission, Neutral/ Reverse/ Park/ Brake selected output is on if the ignition is on and
brake switch activated is on. Otherwise, the Neutral/ Reverse/ Park/ Brake selected output is off.
For vehicles with automatic transmission, the Neutral/ Reverse/ Park/ Brake selected output is on if the ignition is on
and brake switch activated is on, or if the ignition is on and 'gearbox state' is in Neutral, Park or Reverse. Otherwise
Neutral/ Reverse/ Park/ Brake selected output is off.
Shift interlock (where fitted)
On automatic gearbox models, the BCU and IDM combine to operate a shift interlock solenoid, so that the gear
selector lever can only be moved when certain logical conditions have been satisfied. Operation of the interlock may
be affected, if the battery becomes discharged.

+ AUTOMATIC GEARBOX - ZF4HP22 - 24, DESCRIPTION AND OPERATION, Description.
When the gear selector lever is in the Park position and the ignition is off, an interlock solenoid is de-energised, locking
the gear selector lever in the Park position.
The gear selector lever can only be moved from the Park position when the ignition is switched on and the brake pedal
is depressed. When these conditions are satisfied, the brake pedal switch signal is received by the BCU which then
signals the IDM to energise the interlock relay. When the interlock relay is energised, the interlock solenoid is
operated, unlocking the gear selector lever.
When the brake pedal is released, the feed to the BCU is removed and the shift interlock solenoid is de-energised.
The locking mechanism controlled by the solenoid will lock the gear selector lever once it is returned to the Park
position.

HARNESSES
REPAIRS 86-7-19
31.Disconnect main harness multiplug from
engine harness and ABS sensor.
32.Disconnect multiplugs from cruise control
actuator and brake fluid level switch.
33.Withdraw harness to bulkhead.34.Release multiplug from ACE accelerometer.
35.Remove 3 cable tie clips from body and
withdraw harness to bulkhead.
36.Disconnect multiplug from LH horn.
37.Remove LH indicator lamp.

+ LIGHTING, REPAIRS, Lamp - front
repeater - up to 03MY.

HARNESSES
86-7-24 REPAIRS
72.Disconnect 7 multiplugs from ignition passive
coil and steering column switch assembly. 73.Release 3 multiplugs from steering column
support.
74.Disconnect multiplugs from brake and clutch
pedal.
75.Disconnect multiplug from RH side body
harness.
76.Disconnect 2 multiplugs from RH door
harness.
77.Disconnect multiplugs from cruise control
ECU, remove nut securing earth header to
body and remove earth header.