Discovery 2. Manual — part 6

GENERAL INFORMATION

03-17

Electrical Precautions

General
The following guidelines are intended to ensure the
safety of the operator while preventing damage to the
electrical and electronic components fitted to the
vehicle. Where necessary, specific precautions are
detailed in the individual procedures of this manual.

Equipment
Prior to commencing any test procedure on the
vehicle ensure that the relevant test equipment is
working correctly and any harness or connectors are
in good condition. It is particularly important to check
the condition of the lead and plugs of mains operated
equipment.

Polarity
Never reverse connect the vehicle battery and
always ensure the correct polarity when connecting
test equipment.

High voltage circuits
Whenever disconnecting live ht circuits always use
insulated pliers and never allow the open end of the
ht lead to contact other components, particularly
ECU's. Exercise caution when measuring the voltage
on the coil terminals while the engine is running, high
voltage spikes can occur on these terminals.

Connectors and harnesses
The engine compartment of a vehicle is a particularly
hostile environment for electrical components and
connectors:

l

Always ensure electrically related items are dry
and oil free before disconnecting and
connecting test equipment.

l

Ensure disconnected multiplugs and sensors
are protected from being contaminated with oil,
coolant or other solutions. Contamination could
impair performance or result in catastrophic
failure.

l

Never force connectors apart using tools to
prise apart or by pulling on the wiring harness.

l

Always ensure locking tabs are disengaged
before disconnection, and match orientation to
enable correct reconnection.

l

Ensure that any protection (covers, insulation
etc.) is replaced if disturbed.

Having confirmed a component to be faulty:

l

Switch off the ignition and disconnect the
battery.

l

Remove the component and support the
disconnected harness.

l

When replacing the component keep oily hands
away from electrical connection areas and push
connectors home until any locking tabs fully
engage.

Battery disconnection
Before disconnecting the battery, disable the alarm
system and switch off all electrical equipment. If the
radio is to be serviced, ensure the security code has
been deactivated.

CAUTION: To prevent damage to electrical
components, always disconnect the battery
when working on the vehicle's electrical system.
The ground lead must be disconnected first and
reconnected last.

CAUTION: Always ensure that battery leads are
routed correctly and are not close to any
potential chafing points.

Battery charging
Only recharge the battery with it removed from the
vehicle. Always ensure any battery charging area is
well ventilated and that every precaution is taken to
avoid naked flames and sparks.

GENERAL INFORMATION

03-18

Ignition system safety precautions
The vehicle's ignition system produces high voltage
and the following precautions should be observed
before carrying out any work on the system.

WARNING: Before commencing work on an
ignition system, ensure all high tension
terminals, adapters and diagnostic equipment
are adequately insulated and shielded to prevent
accidental personal contacts and minimise the
risk of shock. Wearers of surgically implanted
pacemaker devices should not be in close
proximity of ignition circuits or diagnostic
equipment.

Disciplines
Switch off the ignition prior to making any connection
or disconnection in the system to prevent electrical
surges caused by disconnecting 'live' connections
damaging electronic components.

Ensure hands and work surfaces are clean and free
of grease, swarf, etc. Grease collects dirt which can
cause electrical tracking (short-circuits) or high-
resistance contacts.

When handling printed circuit boards, treat with care
and hold by the edges only; note that some electronic
components are susceptible to body static.

Connectors should never be subjected to forced
removal or refit, especially inter-board connectors.
Damaged contacts can cause short-circuit and open-
circuit fault conditions.

Prior to commencing test, and periodically during a
test, touch a good vehicle body earth to discharge
static charge. Some electronic components are
vulnerable to the static electricity that may be
generated by the operator.

Grease for electrical connectors
Some under bonnet and under body connectors may
be protected against corrosion by the application of a
special grease during vehicle production. Should
connectors be disturbed in service, repaired or
replaced, additional grease should be applied: Part
No. BAU 5811, available in 150 gm tubs.

NOTE: The use of greases other than BAU 5811
must be avoided as they can migrate into relays,
switches etc. contaminating the contacts and leading
to intermittent operation or failure.

Supplementary Restraint System
Precautions

General
The Supplementary Restraint System (SRS)
provides active protection for vehicle occupants in
the event of a serious collision. The system
components include airbags and pretensioner seat
belts which are automatically deployed when a
severe frontal crash condition is detected.

In order to assure system integrity, it is essential that
the SRS system is regularly checked and maintained
so that it is ready for operation in the event of an
accident.

The SRS system contains components which could
be potentially hazardous to the service engineer if
not serviced and handled correctly. The following
guidelines are intended to alert the service engineer
to potential sources of danger and emphasise the
importance of ensuring integrity of the SRS
components fitted to the vehicle.

Where necessary, additional specific precautions are
detailed in the Restraint Systems section of this
Manual which should be referred to prior to
commencing repair operations.

It should be noted that these precautions are not
restricted to operations performed when servicing
the SRS system. The same care should be exercised
when working on ancillary systems and components
located in the vicinity of SRS components; these
include but are not limited to steering system (driver's
airbag), body and trim components (passenger's
airbag and seat belt pretensioners) and electrical
system components (SRS harnesses etc.).

GENERAL INFORMATION

03-19

WARNING: Do not use rear facing child seats in
the front passenger seat if the vehicle is fitted
with a passenger airbag.

WARNING: It is imperative that before any work
is undertaken on the SRS system the appropriate
information is read thoroughly.

WARNING: Replace the airbag every 10 years.

Do not install used SRS parts from another car.
When repairing an SRS system, always use
approved new parts.

Carefully inspect the airbag module before
installing it. Do not install an airbag module that
shows signs of being dropped or improperly
handled, such as dents, cracks or deformation.

Do not try to disassemble or tamper with the
airbag module.

Special bolts are necessary for installing the
airbag module. Do not use other bolts.

Preliminary procedures
The SRS system uses energy reserve capacitors
that keep the system active in the event of electrical
supply failure under crash conditions. It is necessary
to allow the capacitors sufficient time to discharge in
order to avoid the risk of accidental deployment.

Always remove the ignition key from the starter
switch, disconnect the vehicle battery and wait 10
minutes before commencing work on the SRS
system.

Carefully inspect any SRS component before
installation. Do not install any SRS component that
shows signs of damage such as dents, cracks or
deformity.

Component handling

The SRS components are sensitive and potentially
hazardous if not handled correctly; always comply
with the following handling precautions:

l

Never drop an SRS component. The airbag
Diagnostic Control Unit (DCU) is a particularly
shock sensitive device and must be handled
with extreme care. Airbag modules and seat belt
pretensioner units could deploy if subjected to a
strong shock.

l

Never wrap your arms around an airbag
module. If an airbag module has to be carried,
hold it by the cover, with the cover uppermost
and the base away from your body.

l

Never transport airbag modules or seat belt
pretensioners in the cabin of a vehicle. Always
use the luggage compartment of the vehicle for
carrying airbag modules and seat belt
pretensioner units.

WARNING: 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, before the unit
has been deployed.

GENERAL INFORMATION

03-20

Storage

Airbag modules and seat belt pretensioners are
classed as explosive devices. For overnight and
longer term storage, they must be stored in a secure
steel cabinet which has been approved as suitable
for the purpose and has been registered by the local
authority.

For the temporary storage of an airbag module or
seat belt pretensioner during service, place in a
designated storage area. If there is no designated
storage area available, store in the luggage
compartment of the vehicle and inform the workshop
supervisor. Always observe the following
precautions when temporarily storing an airbag
module:

l

Ensure the cover is facing upwards and the
luggage compartment is secured.

l

Always keep components cool, dry and free
from contamination.

l

Do not allow anything to rest on the airbag
module.

l

Store any removed airbag assembly on a
secure flat surface away from electrical
equipment and heat sources exceeding 85

°

C

(185

°

F).

WARNING: Store the airbag module or seat belt
pre-tensioner in a designated storage area. If
there is no designated storage area available,
store in the locked luggage compartment/
loadspace of the vehicle and inform the
workshop supervisor.

Installation and testing precautions
The integrity of SRS system components are critical
for safety reasons. Ensure the following precautions
are always adhered to:

l

Never install used SRS components from
another vehicle or attempt to repair an SRS
component.

l

When repairing an SRS system, only use
genuine new parts.

l

Never apply electrical power to an SRS
component unless instructed to do so as part of
an approved test procedure.

l

Special Torx bolts are necessary for installing
the airbag assembly. Do not use other bolts.
Ensure bolts are tightened to the specified
torque.

l

Ensure that SRS component fixings are
correctly positioned and torqued during service
and repair.

l

Always use new fixings when replacing an SRS
component.

l

Ensure the airbag 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 unit could cause the
system to malfunction.

l

The airbag DCU is a non-serviceable
component and no attempt should be made to
repair or modify the unit.

l

Do not try to disassemble the airbag assembly.
It has no serviceable parts. Once an airbag has
been deployed, it cannot be repaired or reused.

l

If you suspect an airbag assembly could be
defective, install a new unit and dispose of the
old unit. Manually deploy the old unit before
disposal.

WARNING: Keep clear of the deployment zone
when working on or near an airbag module.
Accidental deployment could cause serious
injury.