1999 LAND ROVER DISCOVERY horn

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
DESCRIPTION AND OPERATION 57-5
Description
General
The major steering components comprise an impact absorbing telescopic steering column, a Power Assisted Steering
(PAS) box, a PAS pump, and fluid reservoir. Hydraulic fluid from the fluid reservoir is filtered and then supplied
through the suction line to the inlet on the PAS pump. The PAS pump supplies fluid to the steering box through a
pressure line routed above the front cross member. Fluid returns to the reservoir along the same route through a
return line. On LH drive vehicles the pipe route above the front cross member is still used, the length of pipe acting
as an oil cooler.
To minimise driver's injury in the event of an accident the steering system has a number of safety features including
a collapsible steering column. An additional safety feature is an air bag located in the steering wheel.

+ RESTRAINT SYSTEMS, DESCRIPTION AND OPERATION, Description - SRS.
Steering column assembly and intermediate shaft
The steering column central shaft comprises of two shafts, the upper shaft is splined to accept the steering wheel and
located in bearings in the column tube. A universal joint is located on the bottom of the upper shaft, the joint allows
for angular movement between the upper and lower shafts. The lower shaft is made in two parts, the top section of
the lower shaft is located outside of the lower section. The two sections of the lower shaft are connected by two nylon
injection moulded shear pins. The lower shaft goes through a lower bearing attached to the bulkhead, the lower shaft
is connected by a universal joint to the intermediate shaft in the engine compartment.
Steering column
An upper column tube provides for the location of the steering lock and ignition switch and also the steering switch
gear and a rotary coupler. The rotary coupler provides the electrical connection for the steering wheel mounted airbag,
switches and horn. The upper mounting bracket has two slots, a slotted metal bracket is held in each slot by four resin
shear pins.
The column is mounted on four captive studs which are located on a column mounting bracket. The captive studs
pass through the metal brackets, locknuts secure the steering column to the bulkhead. The two lower mountings are
fixed and cannot move when loads are applied to them. The upper mounting is designed to disengage or deform when
a load is applied, allowing the column to collapse in the event of an accident. The steering column must be replaced
as a complete assembly if necessary.
When an axial load is applied to the upper column tube, energy absorption is achieved by the following mechanism:
lthe mounting bracket deforms,
lthe resin shear pins holding the slotted metal brackets shear,
lthe top mounting bracket slides out of the slotted metal brackets.
The slotted metal brackets remain on the captive studs on the bulkhead. If the column mounting moves, injection
moulded shear pins retaining the two sections of the lower column shaft will shear. This allows the two sections of the
lower shaft to 'telescope' together.
In the event of a collision where the steering box itself moves, two universal joints in the column allow the intermediate
shaft to articulate, minimising movement of the column towards the driver. If movement continues energy absorption
is achieved by the following mechanism:
lthe decouple joint in the intermediate shaft will disengage,
lthe lower section of the steering column shaft will move through the lower bearing,
lthe injection moulded shear pins retaining the two sections of the lower column shaft will shear.
This allows the two sections of the lower shaft to 'telescope' together reducing further column intrusion. Protection to
the drivers face and upper torso is provided by an SRS airbag module located in the centre of the steering wheel.

+ RESTRAINT SYSTEMS, DESCRIPTION AND OPERATION, Description - SRS.

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.

PANEL REPAIRS
REPAIRS 77-2-21
REPAIRS
Front bulkhead assembly
Remove
1.Disconnect both battery leads, negative lead
first.
2.Disconnect leads/multiplug from alternator.
3.Remove front wing.

+ EXTERIOR FITTINGS, REPAIRS,
Wing - front - up to 03MY.
4.Remove washer reservoir.

+ WIPERS AND WASHERS, REPAIRS,
Reservoir - washer - up to 03MY.
5. Models with A/C: Remove condensor.

+ AIR CONDITIONING, REPAIRS,
Condenser.
6. Diesel models: Remove gearbox fluid cooler.
7.Remove RH and LH headlamps.

+ LIGHTING, REPAIRS, Headlamp - up
to 03MY.
8.Release headlamp levelling motors and
position aside.
9.Release headlamp wiring and position aside.
10.Remove battery.

+ CHARGING AND STARTING,
REPAIRS, Battery.
11.Remove battery tray.
12.Remove air filter assembly.

+ ENGINE MANAGEMENT SYSTEM -
Td5, REPAIRS, Air filter assembly.

+ ENGINE MANAGEMENT SYSTEM -
V8, REPAIRS, Air cleaner assembly.
13.Remove 2 earth leads from LH of front
bulkhead.
14.Remove RH horn.

+ ALARM SYSTEM AND HORN,
REPAIR, Vehicle horn.
15. Models with A/C: Release and remove A/C
pipes.
16.Remove RH and LH crush cans.
17.Remove bonnet release cable.
18.Support bonnet in open position
19.Remove bonnet locking mechanism.
20.Remove VIN plate.
21.Remove 2 bolts securing front bulkhead
assembly to chassis.
22.Remove centre braces.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 centre braces.
2.Fit 2 bolts securing bulkhead to chassis and
tighten to 45 Nm (33 lbf.ft).
3.Fit VIN plate.
4.Fit bonnet locking mechanism.
5.Fit bonnet release cable.
6.Fit crush cans.
7. Models with A/C: Fit A/C pipes.
8.Fit RH horn.

+ ALARM SYSTEM AND HORN,
REPAIR, Vehicle horn.
9.Fit 2 earth leads to LH of front bulkhead.
10.Fit air filter assembly.

+ ENGINE MANAGEMENT SYSTEM -
Td5, REPAIRS, Air filter assembly.

+ ENGINE MANAGEMENT SYSTEM -
V8, REPAIRS, Air cleaner assembly.
11.Fit battery tray.
12.Fit battery. Do not connect leads.

+ CHARGING AND STARTING,
REPAIRS, Battery.
13.Fit headlamp wiring and headlamp levelling
motors.
14.Fit RH and LH headlamps.

+ LIGHTING, REPAIRS, Headlamp - up
to 03MY.
15. Diesel models: Fit gearbox fluid cooler.
16. Models with A/C: Fit condensor.

+ AIR CONDITIONING, REPAIRS,
Condenser.
17.Fit washer reservoir.

+ WIPERS AND WASHERS, REPAIRS,
Reservoir - washer - up to 03MY.

PANEL REPAIRS
REPAIRS 77-2-23
Bonnet locking platform
Remove
1.Disconnect both battery leads, negative lead
first.
2.Disconnect leads/multiplug from alternator.
3.Remove front bumper assembly.

+ EXTERIOR FITTINGS, REPAIRS,
Bumper assembly - front.
4. Models with A/C: Remove condensor.

+ AIR CONDITIONING, REPAIRS,
Condenser.
5. Diesel models: Remove gearbox fluid cooler.
6.Remove RH and LH headlamps.

+ LIGHTING, REPAIRS, Headlamp - up
to 03MY.
7.Remove RH and LH repeater lamps.

+ LIGHTING, REPAIRS, Lamp - front
repeater - up to 03MY.
8.Release headlamp wiring and position aside.
9.Remove battery.

+ CHARGING AND STARTING,
REPAIRS, Battery.
10.Remove battery tray.
11.Remove air filter assembly.

+ ENGINE MANAGEMENT SYSTEM -
Td5, REPAIRS, Air filter assembly.

+ ENGINE MANAGEMENT SYSTEM -
V8, REPAIRS, Air cleaner assembly.
12.Remove RH horn.

+ ALARM SYSTEM AND HORN,
REPAIR, Vehicle horn.
13.Remove bonnet release cable.
14.Support bonnet in open position
15.Remove bonnet locking mechanism.
16.Remove VIN plate.
17.Remove centre braces.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 centre braces.
2.Fit VIN plate.
3.Fit bonnet locking mechanism.
4.Fit bonnet release cable.
5.Fit RH horn.

+ ALARM SYSTEM AND HORN,
REPAIR, Vehicle horn.
6.Fit air filter assembly.

+ ENGINE MANAGEMENT SYSTEM -
Td5, REPAIRS, Air filter assembly.

+ ENGINE MANAGEMENT SYSTEM -
V8, REPAIRS, Air cleaner assembly.
7.Fit battery tray.
8.Fit battery. Do not connect leads.

+ CHARGING AND STARTING,
REPAIRS, Battery.
9.Fit headlamp wiring.
10.Fit RH and LH repeater lamps.

+ LIGHTING, REPAIRS, Lamp - front
repeater - up to 03MY.
11.Fit RH and LH headlamps.

+ LIGHTING, REPAIRS, Headlamp - up
to 03MY.
12. Diesel models: Fit gearbox fluid cooler.
13. Models with A/C: Fit condensor.

+ AIR CONDITIONING, REPAIRS,
Condenser.
14.Fit bumper assembly.

+ EXTERIOR FITTINGS, REPAIRS,
Bumper assembly - front.
15.Connect leads/multiplug to alternator.
16.Connect battery leads, negative lead last.

PANEL REPAIRS
77-2-24 REPAIRS
Front cross member
Remove
1.Disconnect both battery leads, negative lead
first.
2.Disconnect leads/multiplug from alternator.
3.Remove washer reservoir.

+ WIPERS AND WASHERS, REPAIRS,
Reservoir - washer - up to 03MY.
4. Models with A/C: Remove condensor.

+ AIR CONDITIONING, REPAIRS,
Condenser.
5. Diesel models: Remove gearbox fluid cooler.
6.Remove RH and LH headlamps.

+ LIGHTING, REPAIRS, Headlamp - up
to 03MY.
7.Release headlamp levelling motors and
position aside.
8.Release headlamp wiring and position aside.
9.Remove RH horn.

+ ALARM SYSTEM AND HORN,
REPAIR, Vehicle horn.
10. Models with A/C: Release and remove A/C
pipes.
11.Remove RH and LH crush cans.
12.Remove 2 bolts securing front bulkhead
assembly to chassis.
13.Remove centre braces.
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 centre braces.
2.Fit 2 bolts securing bulkhead to chassis and
tighten bolts to 45 Nm (33 lbf.ft).
3.Fit crush cans.
4. Models with A/C: Fit A/C pipes.
5.Fit RH horn.

+ ALARM SYSTEM AND HORN,
REPAIR, Vehicle horn.
6.Fit headlamp wiring and headlamp levelling
motors.
7.Fit RH and LH headlamps.

+ LIGHTING, REPAIRS, Headlamp - up
to 03MY.
8. Diesel models: Fit gearbox fluid cooler.
9. Models with A/C: Fit condensor.

+ AIR CONDITIONING, REPAIRS,
Condenser.
10.Fit washer reservoir.

+ WIPERS AND WASHERS, REPAIRS,
Reservoir - washer - up to 03MY.
11.Connect leads/multiplug to alternator.
12.Connect battery leads, negative lead last.

PANEL REPAIRS
REPAIRS 77-2-25
Headlamp mounting panel - RH
Remove
1.Disconnect both battery leads, negative lead
first.
2.Disconnect leads/multiplug from alternator.
3.Remove front bumper assembly.

+ EXTERIOR FITTINGS, REPAIRS,
Bumper assembly - front.
4. Models with A/C: Remove condensor.

+ AIR CONDITIONING, REPAIRS,
Condenser.
5. Diesel models: Remove gearbox fluid cooler.
6.Remove RH headlamp.

+ LIGHTING, REPAIRS, Headlamp - up
to 03MY.
7.Remove RH repeater lamp.

+ LIGHTING, REPAIRS, Lamp - front
repeater - up to 03MY.
8.Release headlamp levelling motor and position
aside.
9.Release headlamp wiring and position aside.
10.Remove battery and battery tray.

+ CHARGING AND STARTING,
REPAIRS, Battery.
11.Remove horn.

+ ALARM SYSTEM AND HORN,
REPAIR, Vehicle horn.
12.Remove RH crush can.
13.Remove 2 bolts securing front bulkhead
assembly to chassis.
14.Remove RH centre brace.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 centre brace.
2.Fit 2 bolts securing bulkhead to chassis and
tighten bolts to 45 Nm (33 lbf.ft).
3.Fit crush can.
4. Models with A/C: Fit A/C pipes.
5.Fit horn.

+ ALARM SYSTEM AND HORN,
REPAIR, Vehicle horn.
6.Fit battery and battery tray. Do not connect
leads.

+ CHARGING AND STARTING,
REPAIRS, Battery.
7.Fit headlamp wiring and headlamp levelling
motors.
8.Fit repeater lamp.

+ LIGHTING, REPAIRS, Lamp - front
repeater - up to 03MY.
M77 1741A