cruise control LAND ROVER DISCOVERY 1995 User Guide

19FUEL SYSTEM
2
DESCRIPTION AND OPERATION CRUISE CONTROL SYSTEM - V8i/Tdi AUTO EDC
Description
The cruise control system consists of
electro-mechanical devices, and comprises of the
following components.
ELECTRONIC CONTROL UNIT (ECU)
The microprocessor based ECU evaluates the signals
provided by the driver controls, brake pedal switch,
clutch pedal switch on manual models, and the
vehicle speed sensor. The ECU activates the vacuum
pump as required. The ECU also has a memory
function for set speed storage.
Driver operated switches
The main cruise control switch is located in the
auxiliary switch panel and activates the cruise control
system. The steering wheel switches provide
'set/accelerate' and 'resume/decelerate' features.
These switches provide the interface between driver
and cruise control system.
Brake pedal switch
The brake pedal switch is located under the lower
dash attached to the brake pedal mounting bracket.
The switch provides for fast disengagement of the
cruise control system and rapid return of the throttle
levers to the idle position when the brake pedal is
applied.
Clutch pedal switch
The clutch pedal switch is located under the lower
dash attached to the clutch pedal mounting bracket.
The switch provides for fast disengagement of the
cruise control system and rapid return of the throttle
levers to the idle position when the clutch pedal is
applied.Vehicle speed sensor
The vehicle speed sensor is located on the side of the
transfer box adjacent to park brake. The sensor
provides road speed data to the ECU. The cruise
control system cannot be engaged until the road
speed exceeds 45 km/h, (28 mph) the system will
automatically disengage at a road speed of 42 km/h
(26 mph).
Vacuum pump
The vacuum pump is energised when the main cruise
control switch is operated, and is actuated by the
steering wheel and brake pedal switches. The pump
provides a vacuum source to the cruise control
actuator. A control valve in the pump provides for
steady increase of road speed or purge of the system
when the brake pedal is applied.
Actuator
The actuator provides the servo mechanism link
between the cruise control system and throttle linkage
and is operated by vacuum from the vacuum pump.
Neutral lockout relay - automatic vehicles
The relay module is located in the right hand side
footwell, accessible by removing the trim casing.
The function of the relay module is to disengage the
cruise control system if neutral, or park, is selected in
the main gearbox, when the system is engaged.
Engine speed trip ECU - Manual vehicles
This unit is located in the right hand side footwell,
accessible by removing the trim casing.
The function of the unit is to disengage cruise control
if engine speed exceeds 5000 rev/min.

CRUISE CONTROL
1
FAULT DIAGNOSIS ROAD TEST
CAUTION: Do not engage cruise control
when vehicle is being used in low transfer
gear or reverse.
WARNING: The use of cruise control is not
recommended on winding, snow covered
or slippery roads or in heavy traffic
conditions where a constant speed cannot be
maintained.
1.Start engine, depress main control switch to
actuate cruise control system. Accelerate to
approximately 50 km/h, (30 mph), operate
'set/acc'switch, immediately release switch,
remove foot from accelerator pedal. Vehicle
should maintain speed at which'set/acc'switch
was operated.
2.Operate'set/acc'switch and hold at that
position, vehicle should accelerate smoothly until
switch is released. Vehicle should now maintain
new speed at which'set/acc'switch was
released.
3.Momentarily touch and release'set/acc'switch,
vehicle speed should increase 1.6 km/h (1 mph)
for each touch. Note that five touches will
increase speed 8 km/h (5 mph).
4.Apply'res/decel'switch while vehicle is in cruise
control mode, cruise control should disengage.
Slow to approximately 55 km/h, (35 mph)
operate'res/decel'switch, immediately release
switch and remove foot from accelerator, vehicle
should smoothly accelerate to previously set
speed. Increase speed using accelerator pedal,
release pedal, vehicle should return to previously
set speed.
NOTE: The cruise control system fitted to
the diesel engine is not as responsive as
that fitted to the petrol engine, due to the
characteristics of diesel engines. Therefore, at
speeds below approx. 65 km/h (40 mph), the
vehicle speed may drop when cruise is selected
and then slowly regain the 'set' speed.5.Operate brake pedal, cruise control system
should immediately disengage returning vehicle
to driver control at accelerator pedal. Operate
'res/decel'switch, vehicle should accelerate to
previously set speed without driver operation of
accelerator pedal.
6.Operate'res/decel'switch and allow vehicle to
decelerate to below 42 km/h, (26 mph). Operate
'res/decel'switch, cruise control system should
remain disengaged.
7.Operate'set/acc'switch below 40 km/h, (28
mph), cruise control system should remain
disengaged. Accelerate, using accelerator pedal
to above 45 km/h, (28 mph), operate'res/decel'
switch, and remove foot from accelerator pedal,
vehicle should smoothly adjust to previously
memorised speed.
8. Automatic vehicles- select neutral, system
should disengage.Manual vehicles- depress
clutch, system should disengage.
9.Cruise at 80 km/h (50 mph), declutch, select
neutral, remove foot from clutch. Operate
'res/decel'switch. Engine should rev to 5000
rev/min, cruise control disengages, engine
returns to idle.
10.Engage forward gear. Operate'res/decel'
switch. Remove foot from accelerator. Speed
should accelerate to previous set speed.
11.Depress main control switch in control system
should immediately disengage and erase
previously set speed from ECU memory.
See
Electrical Trouble Shooting Manual.
ELECTRICAL TESTS
Electrical functionality can be checked using
TestBook.
CABLE SETTING - TDi AUTOMATIC MODELS
1.An incorrectly adjusted kickdown cable can
prevent correct operation of the cruise control
system.
See AUTOMATIC GEARBOX,
Adjustment, kickdown cable adjustment.

CRUISE CONTROL
1
REPAIR BRAKE AND CLUTCH PEDAL SWITCHES/VENT
VALVES
Service repair no - 19.75.34 - Clutch Switch
Service repair no - 19.75.35 - Brake Switch
Remove
1.Remove 3 studs securing driver's side fascia
closing panel.
2.Release and move closing panel aside.
3.Locate and release locking sleeve.
4.Release switch/vent valve from pedal bracket.
5.Disconnect vacuum hose and harness connector
from switch.
6.Remove switch.
Refit
7.Reverse removal procedure.
NOTE: Ensure locking sleeve is correctly
positioned.

19FUEL SYSTEM
2
REPAIR ENGAGEMENT (ON/OFF) SWITCH
Service repair no - 19.75.30
Switch Replacement
Remove
1.Disconnect battery negative lead.
2.Carefully release auxiliary switch panel from
fascia.
3.Disconnect multiplug from switch.
4.Depress retaining lugs on switch, remove switch
from panel.
Bulb replacement
5.Position switch to facilitate removal of bulb.
6.Rotate bulb holder 90°and withdraw it from
switch.CRUISE CONTROL SWITCH
Service repair no - 19.75.36
Remove
1.Disconnect battery negative lead.
2. Models fitted with airbags:Remove driver's
airbag module.
See SUPPLEMENTARY
RESTRAINT SYSTEM, Repair, Driver's
Airbag Module
3. Models without airbags:Turn steering wheel
through 90°. Remove 2 Torx screws securing
pad to steering wheel and remove steering
wheel pad.
4.Disconnect cruise control switch multiplug from
main harness.

CRUISE CONTROL
3
REPAIR
5.Disconnect 2 Lucars from horn contacts.
6.Remove 2 screws securing cruise control switch
to steering wheel.
7.Remove 3 bolts securing mounting bracket to
steering wheel and remove mounting bracket.
8.Remove cruise control switch from steering
wheel.
Refit
9.Reverse removal procedure. Ensuring wiring
harness is routed correctly.
10. Models fitted with airbags:Refit driver's airbag
module and follow all safety precautions.
See
SUPPLEMENTARY RESTRAINT SYSTEM,
Repair, Driver's Airbag Module
ROTARY COUPLER
Service repair no - 19.75.54
The rotary coupler is located behind the steering
wheel. Access is gained by removing the steering
wheel and steering column shroud.
NOTE: On vehicles fitted with airbags.See
SUPPLEMENTARY RESTRAINT SYSTEM,
Repair, Rotary Coupler
Remove
1.Disconnect battery negative lead.
2.Remove steering wheel.
See STEERING,
Repair, Steering Wheel
3.Release 2 turnbuckles securing lower dash
closing panel and lower.
4.Remove 3 screws securing lower half of shroud
to steering column.
5.Disconnect rotary coupler multiplug from
steering column harness.

CRUISE CONTROL
5
REPAIR ACTUATOR LINK-SETTING - V8i
Service repair no - 19.75.21
NOTE: Setting procedure is carried out at
minimum throttle condition only.
1.Ensure ignition is switched 'OFF'.
2.Check clearance between inside edge of
actuator link and recessed diameter of throttle
lever. Clearance should be 0.2 to 2.0 mm.
Link - adjust
3.Remove link from actuator.
4.Rotate socket joint adjuster as necessary.
5.Refit link to actuator and recheck clearance
between link and lever.
6.With throttle fully open, check a gap of at least
3mm exists between side of link ("A" in
illustration) and side of small spring ("B" in
illustration). Realign link by bending to achieve
correct gap. Recheck clearance at closed
throttle/open throttle. Check link slides smoothly
in groove of throttle lever.

CRUISE CONTROL
7
REPAIR CRUISE CONTROL ECU - V8i
Service repair no - 19.75.49
Remove
1.Remove lower dash panel.
2.Disconnect ECU multi-plug.
3.Remove ECU fixing.
4.Remove ECU.
5.Reverse removal procedure. Ensuring that
electrical multi-plug is securely reconnected.
SPEED TRIP ECU - MANUAL V8i
NOTE: The neutral lock out relay
module/speed trip ECU is mounted in the
right hand side footwell. To identify
components.
See Electrical Trouble Shooting
Manual.
VEHICLE SPEED SENSOR
Service repair no - 18.30.22
For Tdi
See FUEL SYSTEM Tdi, Repair, Vehicle
Speed Sensor
For V8iSee FUEL SYSTEM MFI, Repair, Vehicle
Speed Sensor
NEUTRAL LOCK OUT RELAY
Service repair no - 19.75.28
1.Remove 3 studs securing fascia right hand side
closing panel.
2.Release and move closing panel aside.
3.Remove 2 studs securing right hand side 'A' post
lower trim casing.
4.Remove casing.
5.Locate relay (neutral coloured base) and release
base from bracket.
6.Remove relay.
NOTE: For further information.See
Electrical Trouble Shooting Manual.
Refit
7.Reverse removal procedure.

CRUISE CONTROL
9
REPAIR CRUISE CONTROL ECU - Tdi
Service repair no - 19.75.49
Remove
1.Remove 4 studs securing fascia left hand
closing panel.
2.Remove closing panel.
3.Remove nut securing ECU/relay bracket.
4.Lower bracket for access.
5.Remove bottom nut securing ECU to bracket.
6.Open glove box, align stops with cut-outs in
fascia panel and lower.
7.Move SRS harness aside.
8.Remove top nut securing ECU to bracket.
9.Disconnect ECU multiplug.
10.Remove ECU.
Refit
11.Reverse removal procedure. Ensure electrical
multiplug is securely reconnected.

STEERING
3
DESCRIPTION AND OPERATION Steering column components
1. Upper shroud
2. Column harness
3. Cruise control switch (if fitted)
4. Steering wheel and nut
5. Rotary coupler
6. Column switch
7. Shear bolts
8. Switch saddle
9. Upper steering column
10. Universal joint
11. Universal joint bolt
12. Steering column lock assembly13. Lower shroud
14. Column lock/ignition
15. Air bag mounting bracket (if fitted)
16. Air bag module
17. Steering pad (non-airbag)
18. Lower shaft
19. Rubber coupling
20. Compression joint
21. Universal joint
22. Universal joint bolt

SUPPLEMENTARY RESTRAINT SYSTEM
3
REPAIR
8.Disconnect harness connector from airbag
module.
9.Remove airbag module.
CAUTION: Store the airbag module in
accordance with the storage procedures
outlined in Description and Operation.
NOTE: If airbag module is to be replaced
the serial numbers must be recorded in
the vehicle service record.
Refit
10.Reverse removal procedure.
11.Connect harness connector to airbag module
with harness downwards (as shown at 8).
12.Position airbag module on steering wheel and
engage retained screws. Use special socket to
tighten screws to
8Nm (6 lbf ft).
CAUTION: Take care not to cross thread
screws.
13.Check Supplementary Restraint System using
Testbook.STEERING WHEEL
Service repair no - 57.60.01
Remove
1.Remove driver's airbag module.
See driver's
airbag module.
2.Position steering wheel so the road wheels are
in the straight ahead position.
3.Disconnect cruise control switch connector
(where fitted) from rotary coupler harness.
4.Release harnesses from clip on steering wheel.
5.Remove steering wheel nut.
6.Release steering wheel from column.
7.Feed harnesses through hole in steering wheel.
8.Remove steering wheel.
CAUTION: Prevent rotation of rotary
coupler once steering wheel is removed.
Secure in position with adhesive tape.