1995 LAND ROVER DISCOVERY airbag

75SUPPLEMENTARY RESTRAINT SYSTEM
2
DESCRIPTION AND OPERATION OPERATION
The airbag supplementary restraint system (SRS) is a
safety device which, when used in conjunction with
the seat belt, is designed to protect the driver and
front passenger.
Two different SRS systems are fitted to Discovery.
The Distributed SRS which has two crash sensors
located in the engine compartment on the chassis
longitudinals and the Single Point Sensing (SPS) SRS
which has a single crash sensor located in the Airbag
diagnostic control unit.
The change from distributed SRS to SPS SRS
occurred at VINs198222and528977.
Distributed SRS
In the event of a frontal impact, when the airbag
diagnostic control unit and one of the airbag crash
sensors senses the impact, the diagnostic control unit
fires igniters. This in turn ignites tablets of sodium
azide which generate a large amount of Nitrogen gas
leading to airbag inflation in approximately 30
milli-seconds.SPS SRS
In the event of a frontal impact, when the airbag
diagnostic control unit senses the impact, the
diagnostic control unit fires igniters. This in turn ignites
tablets of sodium azide which generate a large
amount of Nitrogen gas leading to airbag inflation in
approximately 30 milli-seconds.
All Models
When fully deployed the airbag offers additional
protection to the front seat occupant. As an occupant
moves into the airbag it immediately discharges the
gas to provide progressive occupant deceleration and
reduce risk of injuries. The whole process is
completed in approximately 0.3 seconds.
WARNING: All the airbag system
components, including the wiring harness,
MUST be renewed after the airbags have
deployed.

SUPPLEMENTARY RESTRAINT SYSTEM
3
DESCRIPTION AND OPERATION SRS warning light (airbag)
Distributed SRS
The warning light in the instrument pack illuminates
after the electrical circuits are switched on whilst a
system check is carried out. After about 8 seconds the
warning light will go out. The system checks airbag
diagnostic control unit, airbag crash sensors, airbag
harness, driver and passenger modules.
SPS SRS
The warning light in the instrument pack illuminates
after the electrical circuits are switched on whilst a
system check is carried out. After about 5 seconds the
warning light will go out. The system checks airbag
diagnostic control unit, airbag harness, driver and
passenger modules.
All Models
In the event of a fault in the system the warning light
will illuminate. The airbag diagnostic control unit logs
the fault which can only be accessed using TestBook.

75SUPPLEMENTARY RESTRAINT SYSTEM
4
DESCRIPTION AND OPERATION GENERAL PRECAUTIONS
Impacts which do not deploy airbags
CAUTION: Check for structural damage in
the area of the impact, paying particular
attention to bumper armatures,
longitudinals, crash cans and bracketry.
1.Carefully inspect any airbag part before
installing. Do not install any part that shows
signs of being dropped or improperly handled,
such as dents, cracks or deformation.
2.Always remove the key from the starter switch
before beginning work.
3.Always disconnect both the negative '-' cable
and positive '+' cable at the battery before
removal of driver or passenger airbag modules.
Disconnect the negative cable first.
CAUTION: The airbag system has
sufficient stored energy to deploy airbags
for up to 20 minutes.
4.To continue work immediately, disconnect the
driver's airbag and passenger's airbag (where
fitted).
5.Do not try to dismantle the airbag module. There
are NO separately serviceable parts. Once an
airbag has been deployed, it cannot be repaired
or reused.
6.Do not install used airbag parts from another
vehicle. When repairing, use only new airbag
parts.

SUPPLEMENTARY RESTRAINT SYSTEM
5
DESCRIPTION AND OPERATION
7.Do not use electrical test equipment on the
airbag harness or connectors. Tampering with or
disconnecting the harness could result in
accidental firing of the airbag or make the
system inoperative, which may result in serious
injury.
8. An airbag system fault can only be
diagnosed using TestBook.
9.The airbag module contains Sodium Azide which
is poisonous and extremely flammable. Contact
with water, acid or heavy metals may produce
harmful or explosive compounds. Do not
dismantle, incinerate or bring into contact with
electricity.VEHICLE RECOVERY
Towing - airbag not deployed
Normal towing procedures are unlikely to cause an
airbag to deploy. However, as a precaution switch the
ignition off and then disconnect both battery leads.
Disconnect the negative '-' lead first.
Towing - airbag deployed
Once the driver's airbag has been deployed the
vehicle must have a front suspended tow. However,
as a precaution switch the ignition off and then
disconnect both battery leads. Disconnect the
negative '-' lead first.

75SUPPLEMENTARY RESTRAINT SYSTEM
6
DESCRIPTION AND OPERATION AIRBAG STORAGE
Temporary storage
For temporary storage of the airbag module during
service, observe the following precautions:
Store the airbag module with the pad surface up.
Place the airbag module in designated storage area.
If no designated storage area is available, the module
may be stored in the boot of the vehicle from which it
was removed. Always lock the boot when module is
stored in it and inform workshop supervisor.
WARNING: If the airbag is improperly
stored face down, accidental deployment
could propel the unit with enough force to
cause serious injury.
Store the removed airbag module on a secure flat
surface away from heat, oil, grease, detergent or
water.
CAUTION: Improper handling or storage
can internally damage the airbag module,
making it inoperative. If you suspect the
airbag module has been damaged, install a new
unit.
Overnight storage
Airbag modules are classed as an explosive article
and as such they must be stored in a secure steel
cabinet which has been approved by the local
authority.

SUPPLEMENTARY RESTRAINT SYSTEM
1
FAULT DIAGNOSIS CRASH SENSOR INSPECTION - DISTRIBUTED
SRS
1.After any degree of front body damage, inspect
both front crash sensors. Replace a sensor if
there are any signs of dents, cracks or
deformation.
2.Ensure the sensors are installed correctly. There
must be no gap between the sensor and body of
the vehicle. Use the fixing screws supplied with
the sensor and tighten to the correct torque.
Tighten front sensor fixing before rear sensor
fixing.
CAUTION: Take extra care when painting
or doing body work in the vicinity of the
sensors. Avoid direct exposure of the
sensors or harness to heat guns, welding or
spraying equipment.AIRBAG HARNESS
1.Never attempt to modify, splice or repair the
airbag harness. Never install electronic
equipment such as; a mobile telephone, two-way
radio or in-car entertainment system in such a
way that it interferes electrically with the airbag
harness.
NOTE: The airbag harness can be
identified by a special yellow outer
protective covering.
2.Make sure the airbag harness is installed
correctly and not pinched or trapped.
3.Ensure all airbag harness connectors are mated
correctly and securely fastened. Do not leave the
connectors hanging loose.

75SUPPLEMENTARY RESTRAINT SYSTEM
2
FAULT DIAGNOSIS WARNING LABELS
1.Bonnet locking platform
Refer to the Owner's Handbook for information on the
airbag system.
2.Rotary coupler
CAUTION: Ensure wheels are straight
ahead before removal and installation.
3.Driver's sun visor
Refer to the Owner's Handbook for information on the
airbag system.

SUPPLEMENTARY RESTRAINT SYSTEM
3
FAULT DIAGNOSIS
4.Airbag modules
A- If defective, replace and dispose of the entire unit
as directed in the instructions. Under no
circumstances should a diagnosis be performed using
electrically powered test equipment or probing
devices.
B- Tampering or mishandling can result in personal
injury. For special handling instruction refer to the
Workshop manual. This airbag module cannot be
repaired. Use diagnostic instructions to determine if
the unit is defective.
C- ROVER Bar code - The code number must be
recorded if the airbag module is to be replaced.
5.Steering wheel
Refer to the Owner's Handbook for information
on the airbag system.