sensor LAND ROVER DISCOVERY 2002 Workshop Manual

RESTRAINT SYSTEMS
75-8 DESCRIPTION AND OPERATION
Diagnostic and Control Unit (DCU)
The SRS DCU is an electronic single point crash sensor. It is capable of sensing if a crash has taken place. If all the
relevant parameters are met, then the DCU deploys the airbag(s) and seat belt pretensioners.
The DCU is bolted to the transmission tunnel beneath the centre console in the area of the handbrake.
The DCU performs the following functions:
lInternal self test, system monitoring and fault detection.
lSRS warning lamp operation.
lSystem deployment.
Self test, system monitoring and fault detection
The DCU performs a self-test during start-up and then continually during operation of the system. The following
components are tested:
lThe decelerometer.
lThe electromechanical safing sensor.
lThe microprocessor.
lThe continuity of squib ignition circuits.
lThe SRS warning lamp.
If the DCU detects a fault, it stores the fault code in memory. Diagnose the DCU with TestBook. The DCU cannot
be serviced. It must be replaced if it is faulty.
SRS warning lamp operation
The DCU controls the SRS warning lamp contained in the instrument cluster.
System deployment
The DCU determines when the system deploys based on inputs from both the decelerometer and the
electromechanical safing sensor. Both are located within the DCU. Neither are serviceable.
The electromechanical safing sensor uses a magnet and ball bearing system to provide a mechanical confirmation of
vehicle deceleration. The ball bearing is held in place by the magnet. The strength of the magnet is calibrated such
that the force required for the ball bearing to move away from the magnet will only occur if the vehicle decelerates
suddenly, as in an accident.
The SRS deploys only if both the decelerometer reading and the safing sensor operation occur at the same time.

RESTRAINT SYSTEMS
DESCRIPTION AND OPERATION 75-9
Operation - SRS
The diagnostic and control unit (DCU) controls the SRS system. The DCU is located beneath the centre console close
to the handbrake area. The DCU contains both an electronic deceleration sensor as well as an electromechanical
safing sensor. When the electronic deceleration sensor within the DCU detects rapid deceleration of the vehicle, it
compares the deceleration rate with stored values in its' memory. If the deceleration rate exceeds the stored value
and the electromechanical safing sensor triggers, the DCU deploys the airbag and the seat belt pretensioners. The
DCU will not deploy the airbags and seat belt pretensioners unless both sensors trigger.
The SRS has diagnostic capabilities through TestBook. In the event that a fault is detected, the DCU alerts the driver
by illuminating a warning lamp in the instrument cluster.
The DCU controls the following:
lSRS warning lamp.
lDrivers airbag module.
lPassenger airbag module (where fitted).
lDriver seat belt pretensioner.
lPassenger seat belt pretensioner.
WARNING: The integrity of the SRS system are critical for safety reasons. Ensure the following precautions
are always adhered to:
lNever install used SRS components from another vehicle or attempt to repair an SRS component.
lWhen repairing an SRS system only use genuine new parts.
lNever apply electrical power to an SRS component unless instructed to do so as part of an approved test
procedure.
lSpecial Torx bolts are necessary for installing the airbag module - do not use other bolts. Ensure bolts
are tightened to the correct torque.
lAlways use new fixings when replacing an SRS component.
lEnsure the SRS Diagnostic Control Unit (DCU) is always installed correctly. There must not be any gap
between the DCU and the bracket to which it is mounted. An incorrectly mounted DCU could cause the
system to malfunction.
System deployment
The airbag and seat belt pretensioners deploy to protect the front seat occupants when the DCU senses a rapid
vehicle deceleration. The system deploys when the following conditions are met:
lThe ignition switch is on.
lThe vehicle decelerates beyond a threshold defined within the DCU.
lThe electromechanical safing sensor within the DCU triggers.
When all of the above conditions are met, the DCU deploys the airbag(s) and seat belt pretensioners. If the above
conditions are not met, the DCU will not deploy the system.
Component replacement policy
After an impact which deploys the airbags and pretensioners, the following components must be renewed:
lDCU.
lDriver and passenger airbag modules.
lDriver and passenger buckle pretensioners.
lRotary coupler.
lFlyleads (where applicable) connecting airbags and pre-tensioners to SRS harness

RESTRAINT SYSTEMS
DESCRIPTION AND OPERATION 75-11
DESCRIPTION AND OPERAT ION
Description - seat belts
An inertia reel, three point seat belt is installed at each seat position. The inertia reels incorporate a liftshaft locking
system with webbing sensor and car sensor activating mechanisms. The webbing sensor activates the locking system
if the webbing is subjected to a sharp pull. The car sensor activates the locking system if the vehicle is subjected to
sudden deceleration or a severe tilt angle.
Front seat belts
The inertia reel of each front seat belt is attached to the related B/C post, behind the finishers. The webbing runs from
the inertia reel, through a height adjuster, to an anchor point at the base of the B/C post. The buckle assembly for
each belt is attached to the inboard side of the seat and contains the SRS pretensioner.
Rear seat belts
The inertia reels for the outboard rear seats are attached to the body behind the loadspace side trim casings. The
webbing runs from each inertia reel through an upper mounting, suspended from the cantrail, to an anchor point on
the rear wheel arch.
The inertia reel of the centre rear seat is mounted in the back of the seat. The webbing runs through a guide on the
top of the seat and is anchored to one of the seat hinge points. The buckles for the rear seat belts are also attached
to the seat hinge points.
Third row seat belts
The inertia reel of each third row rear seat belt is attached to the related E post, behind the loadspace side trim
casing.The webbing runs from the inertia reel, through an upper mounting on the E post to an anchor point on the
loadspace floor. The buckle is mounted on the inboard side of the seat.

EXTERIOR FITTINGS
REPAIRS 76-2-13
4.Remove 2 bolts securing bumper.
5.With assistance remove bumper.
NOTE: Do not carry out further dismantling if
component is removed for access only.
6.Remove 7 bolts and 5 screws securing closing
panel and remove panel.7.Disconnect 4 park distance control sensor
harness multiplugs and remove 6 clips
retaining harness.
8.Release 3 clips retaining harness and remove
harness.
9.Noting their fitted positions, release and
remove 4 park distance control sensors and
sensor housings.
Refit
1.Fit sensor housings to bumper, ensuring lugs
on housings are aligned with cut-outs in
bumper.
2.Fit and secure sensors to housings.
3.Fit harness, secure with clips and connect
multiplugs
4.Fit closing panel and secure with bolts and
screws.
5.With assistance, fit bumper assembly to body.
6.Fit bolts securing bumper and tighten to 45 Nm
(33 lbf.ft).
7.Secure rear lamp harness clips and connect
park distance control sensor harness multiplug.
8.Fit both rear tail lamps.

+ LIGHTING, REPAIRS, Lamp - tail/
flasher - bumper.

INTERIOR TRIM COMPONENTS
76-3-4 REPAIRS
8. Models with volumetric alarm:
aRelease volumetric sensor from trim casing.
bDisconnect multiplug from volumetric
sensor.
cRemove volumetric sensor.
9.Remove rear seat belt blanking plate.
10.Release 2 clips securing trim casing to body.
11.Remove trim casing.
Refit
1.Fit trim casing and secure with clips.
2.Fit rear seat belt blanking plate.
3. Models with volumetric alarm:
aPosition volumetric sensor to trim casing
and connect multiplug.
bFit volumetric sensor to trim casing.
4. Models with third row seats:
aFit lower anchorage of third row seat belt
and tighten bolt to 32 Nm (24 lbf.ft).
bFit cap to lower anchorage bolt.
cFit third row seat belt escutcheon to trim
casing.
5.Fit trim clips securing trim casing to body.
6.Position grab handle and spacers to trim
casing.
7.Fit and tighten bolts securing grab handle to
body to 3 Nm (2.2 lbf.ft).
8.Close caps on ends of grab handle.
9.Fit tail door aperture upper trim casing.
10.Reposition rear seat.
Console - centre - automatic models
$% 76.25.01
Remove
1.Select position 'D', remove gear selector knob
and collect spacer.
2. Models from 03MY:Remove both centre
console cup holders.
3.Release selector panel, disconnect multiplug
and remove panel .
4.Release clips securing transfer box lever gaiter
to centre console and remove knob and gaiter.

INTERIOR TRIM COMPONENTS
REPAIRS 76-3-13
Panel - auxiliary switch
$% 76.46.38
Remove
1.Carefully remove electric exterior mirror switch
from auxiliary switch panel and disconnect
multiplug.
2. Models with headlamp levelling: Release
knob and remove nut securing headlamp
levelling switch to auxiliary switch panel.
3.Release 2 fasteners and open fascia access
panel.
4. Models with headlamp levelling: Remove
headlamp levelling switch from auxiliary switch
panel and disconnect multiplug.
5. Models with A/C: Remove 2 screws securing
in-car temperature sensor to auxiliary switch
panel.
6. Models with A/C: Disconnect multiplug from
in-car temperature sensor and remove from
auxiliary switch panel.
7.Release 2 clips securing auxiliary switch panel
to fascia and remove panel.
Refit
1.Position auxiliary switch panel to fascia and clip
into position.
2. Models with A/C: Connect multiplug to in-car
temperature sensor.
3. Models with A/C: Position in-car temperature
sensor to auxiliary switch panel and secure with
screws.
4. Models with headlamp levelling: Position
headlamp levelling switch to auxiliary switch
panel and secure with nut.5. Models with headlamp levelling: Replace
cap and connect multiplug to headlamp
levelling switch.
6.Connect multiplug to exterior mirror switch and
fit switch to auxiliary switch panel.

INTERIOR TRIM COMPONENTS
REPAIRS 76-3-21
24.Remove front sunroof aperture trim.
25.Release end caps from all grab handles.
26.Remove 2 bolts securing each grab handle to
roof.
27.Remove all 4 grab handles.
28. Models with volumetric alarm: Release front
volumetric sensor from headlining and
disconnect multiplug.
29. Models with rear A/C:
aRelease rear A/C control panel from
headlining.
bDisconnect 2 multiplugs and 2 Lucar
connectors from rear A/C control panel.
cRemove rear A/C control panel.
30.Release rear interior lamp from headlining and
disconnect multiplug.
31.Remove rear interior lamp. 32.Remove 2 clips securing rear of headlining to
roof.
33.Release rear sunroof switch from headlining.
34.Disconnect multiplug and remove rear sunroof
switch.
35.Remove screw securing headlining to roof.
36.With assistance, remove headlining.
37. Models with rear A/C:
aRemove foam pads from air vents.
bRelease 2 rear air vents from headlining.
cRelease 3 central air vents from headlining.

INTERIOR TRIM COMPONENTS
76-3-22 REPAIRS
38.Remove 7 nuts securing each stowage pocket
to headlining and collect mounting plates.
39.Remove both pockets from headlining.
40.Remove 8 screws securing rear console to
headlining and collect 3 mounting plates.
41.Remove rear console from headlining.
Refit
1.Fit rear console and mounting plates to
headlining.
2.Fit and tighten nuts securing rear console to
headlining.
3.Fit both stowage pockets and mounting plates
to headlining.
4.Fit and tighten nuts securing stowage pockets
to headlining.
5. Models with rear A/C:
aFit 3 central air vents to headlining.
bFit 2 rear air vents to headlining.
cFit foam pads to air vents.
6.With assistance, position headlining in vehicle.
7.Fit and tighten screw securing centre of
headlining to roof.
8.Connect multiplug to rear sunroof switch.
9.Fit rear sunroof switch to rear console.
10.Fit clips securing rear edge of headlining to
sunroof. 11.Position rear interior lamp to headlining and
connect multiplug.
12.Fit rear interior lamp to headlining.
13. Models with rear A/C:
aPosition rear A/C control panel to headlining
and connect multiplugs and Lucar
connectors.
bFit rear A/C control panel to headlining.
14. Models with volumetric alarm: Connect
multiplug to front volumetric sensor and fit
sensor to headlining.
15.Fit grab handles to headlining and secure with
bolts.
16.Fit end caps to grab handles.
17.Fit front sunroof aperture trim.
18.Fit rear sunroof aperture trim.
19.Fit tail door aperture upper trim casing.
20.Fit sun visor clips to headlining and secure with
screws.
21.Fit caps to sun visor clips.
22.Position front stowage pocket to headlining and
connect multiplugs to sunroof switches.
23.Fit and tighten 10 screws securing front
stowage pocket to headlining.
24.Connect multiplug to front interior lamp.
25.Fit front interior lamp to headlining and secure
with nuts.
26.Fit lens to front interior lamp.
27.Fit and tighten screw securing front stowage
pocket to headlining.
28.Fit access panel to front edge of front stowage
pocket.
29.Position sun visor to headlining and secure to
clip.
30.Connect multiplug to sun visor.
31.Fit and tighten screws securing sun visor to
headlining.
32.Repeat process for second sun visor.
33. Models with premium ICE: Position both 'A'
post trim casings and connect multiplugs to
speakers.
34.Fit both trim casings to 'A' posts and secure
with clips.
35.Fit both 'B' post upper trim casings.

+ INTERIOR TRIM COMPONENTS,
REPAIRS, Trim casing - upper - 'B' post.
36.Fit both 'D' post trim casings.

+ INTERIOR TRIM COMPONENTS,
REPAIRS, Trim casing - 'D' post.

SEATS
DESCRIPTION AND OPERATION 76-5-11
Description - heated seats
Heated seats
The heated seat system is available on both manual seats and electric seats. The electrical sub-system consists of
the following components:
lSeat heater switches.
lSeat heater elements.
lTemperature control unit (if electric seats are fitted).
lTemperature sensor (if electric seats are fitted).
lThermostat (if manual seats are fitted).
Seat heater switches
The seat heater switches supply an ignition feed to either the temperature control unit (vehicles with electric seats) or
directly to the seat heater elements (vehicles with manual seats). When a seat heater switch is operated, current flows
to the seat heater elements causing them to heat the seat.
The ignition feed comes from fuse 15 in the passenger compartment fuse box.
Seat heater elements
The seat heater elements are located in the seat cushion and squab. The cushion and squab heater elements are
wired in series. Total power consumption at 13.5 volts is approximately 115 Watts.
The cushion heater element has an input feed from the temperature control unit or heater switch and an output to the
squab heater element, which outputs to earth.

SEATS
76-5-12 DESCRIPTION AND OPERATION
Temperature control unit
The temperature control unit is only fitted to vehicles with electric seats. Feed back of the seat temperature is via a
Negative Temperature Coefficient (NTC) sensor within the seat cushion. Resistance of this sensor changes with the
temperature of the seat cushion allowing the temperature control unit to lower or raise the voltage to the seat heater
elements to raise or lower their temperature.
An ignition feed is supplied via the seat heater switch. The temperature sensor supplies an input. Output is a supply
to the cushion heater element and an earth.
Thermostat
On vehicles with non electric seats, the temperature is controlled by a thermostat located in the seat cushion. The
thermostat interrupts the power supply when it reaches a pre-determined temperature.