service ASTON MARTIN DB7 1997 Workshop Manual

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Introduction
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Introduction '-^;^'^<-~'
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Workshop Manual Sections
The
DB7
Workshop Manual
is
divided .jnto,9seGtipnsE.a&foli
1 Engine

2.
Fuel,
Emission Control
and
Exhaust
3. Transmission

4.
Suspension
and
Steering
5. Brakes, Wheels
and
Tyres
6. Electrics
7. Chassis
and
Body
8.
Air
Conditioning
9. Aston Martin Diagnostic System
Procedure Numbering
The workshop manual procedures
are
numbered using
the
parts list numbers
as a key. The
first
two
digits
oi a

workshop manual procedure number
are
also
the
parts list number
(e.g.
1.5.01
Sump Removal relates
to PL 1.5 Oil

Pump
and
Sump). Thus when carrying
out a
procedure,
you can
quickly locate
the
relevant parts illustration
and

spare parts list.
To avoid excessive repetition, each procedure will
be
fully detailed once
in its
appropriate place
in the
manual.
In

any other location where this procedure
is
required,
it
will
be
referenced only
by its
title
and its
procedure number.
Special Tools
Where special service tools
are
required
to
perform
an
operation,
the
tool number
is
recorded
at the
point
of use

within
the
procedure.
An
index
and
illustrated list
is
provided
in
this section
for the
purpose
of
identifying special

tools.

References
References
to the
left, right, front
or
rear
of
the vehicle
or of
a component
are
always made as
if
sitting
in the
drivers
seat facing forward.
Any
such references
to
assemblies removed from
the
vehicle
are to the
normal orientation
of

the assembly when fitted
in the
vehicle.
Repairs
and
Replacements
Where replacement parts
are
required,
it is
essential that only genuine Aston Martin parts
are
used. Your attention
is drawn
to the
following points concerning repairs
and the
fitting
of
genuine Aston Martin parts
and
accessories:
• Safety features embodied
in the
vehicle
may be
impaired
if
other than genuine Aston Martin parts
are
fitted.
In certain territories, legislation prohibits
the
fitting
of
parts which
are not
produced
to the
manufacturers
specification.
• Adhere
to
torque wrench settings given
in
this manual.
• Locking devices, where specified, must
be
fitted.
If the
efficiency
of a
locking device
is
impaired during

removal,
it
must
be
renewed.
•
The
vehicle warranty
may be
invalidated
by the
fitting
of
other than genuine Aston Martin parts.
April
1997 Hi

Introduction
/^r"^^^^^3^
'"'P ?
Safety Precautions L —^ ^^—^
Safety Precautions "
All service workshops are a source of potential danger and repair work should only be performed by technically
trained staff following the procedures in this manual. A safety conscious approach to the performance of all service
procedures must be observed at all times. Statutory requirements governing all aspects of health and safety at work
including directives for the proper use of materials and equipment must be implemented.
The following contains a list of particular safety precautions which should be observed; it is not intended to be
exhaustive.
Air Conditioning System
Do not disconnect any air conditioning refrigerant system pipes unless trained and instructed to do
so.
The refrigerant
used can cause blindness if allowed to contact your eyes.
Chemical Handling and Storage
Chemicalsusedintheservicingofmotorvehiclesincludeacids,adhesives, antifreeze, brake fluids, coolants, grease,

oil,
paint, resin and solvents. Exposure to certain chemicals through direct contact or inhalation can be
fatal.

Potential hazards may also be present through the incorrect use, storage and handling of chemicals causing a fire
risk. The following precautions should be observed.

1.
Strictly adhere to handling and safety information found on containers and labels.

2.
Do not store chemicals in unlabelled or incorrectly labelled containers.
3. Containers used for storing chemicals should not be left
open;
there is a risk of
spilling,
or evaporation of fumes
which may be inflammable or toxic.

4.
Do not mix chemicals unless instructed to do so following manufacturers guidelines.
5. Do not inhale chemical materials to determine identity, they may be toxic.
6. Do not use petrol, kerosene, diesel
fuel,
gas oil, thinners or solvents for washing
skin.

7. Containers whose capacity is over 25 litres (5 gallons) require a bund wall in order to contain spillages.
8. Chemicals based on solvents such as paint should not be sprayed in a confined space; work areas used for
such operations should be well ventilated and fume extraction equipment should be utilised.
9. Ensure that adequate ventilation is provided when volatile de-greasing agents are being used.
WARNING: Fume extraction equipment must be in operation when
solvents
are
used
e.g.
trichloroethane, white
spirit, SBP3, methylene chloride, perchlorethylene.
WARNING: Do not smoke in the vicinity of volatile de-greasing agents.

10.
Avoid splashing the
skin,
eyes and clothing.

11.
Clean chemicals from the skin and clothing as soon as possible after soiling.

12.
Wear protective clothing such as goggles, non porous gloves and apron when hand
I
ing battery acid and other
corrosive and toxic substances.
iv April 1997

//—-^
^^^^5~^
' -^ ^ Introduction
Safety Precautions
Safety Precautions (continued)
Electrical Equipment

1.
Ensure that electrical equipment is in safe working order before use.

2.
Inspect power leads of all mains electrical equipment for damage and security, and check that it is properly

earthed.

3. Ensure that electrical equipment is protected by a fuse of the correct current rating.

4.
Disconnect the battery before commencing repair operations to the electrical system, fuel system and engine
or when working beneath the vehicle.
Exhaust Fumes
Engines should not be run in confined spaces, exhaust fumes contain harmful and toxic substances including carbon
monoxide which can prove fatal if inhaled. Engines must only be run where there is fume extraction equipment in
operation or where there is adequate ventilation.
Fire Precautions

1.
Ensure that a suitable form of fire extinguisher is conveniently located near the work area.

2.
Keep oils, solvents and combustible materials away from naked flames and other sources of ignition.
3. Ensure that NO SMOKING signs are posted around areas where combustible materials and vapour may be
present and ensure that the warnings are strictly observed.

4.
Ensure that dry sand is available to soak up any spillage of fuel or other flammable solutions.
5. Fume extraction equipment must be available and in full working order to remove combustible and toxic
vapours.
6. All personnel should be aware of the fire drill procedures and precautions.
Jacking and Lifting

1.
The recommended procedures for lifting, jacking and towing are included latefin this seetion-and must be
strictly observed to ensure personal safety.

2.
Always use a vehicle hoist, ramp or pit for working beneath the car in preferencetd^&^cking
3. Never rely on a jack to support a car independently, use axle stands or blocks carefully pJaQed at the jacking
points to provide rigid support.

4.
When working beneath a vehicle, chock the wheels as well as applying the handbrake.
5. Ensure that the vehicle is standing on firm level ground before jacking or lifting.
5. Check any lifting equipment used has adequate capacity for the load being lifted and is ih"fdll working order.
Tools and Equipment

1.
Do not leave tools, equipment, spilt oil, etc. around or on the work area.

2.
Ensure that tools and equipment used are in good condition; do not use damaged or defective tools or
equipment.
3. Do not apply heat in an attempt to free stiff nuts or fittings; as well as causing damage to protective coatings,
there is a risk of damage to electronic equipment and brake lines from stray heat.

4.
Use the recommended service tool where instructed to do so.
April 1997 v

Electrics
Airbag System
Airbag (Supplementary Restraint System)
Repair Procedures
Description
Two airbaes are fitted to the 97 model year DB7.
The drivers airbag is located in the centre of the
steering wheel (Fig 1-1), the passenger airbag is
located behind the fascia panel (Fig 1-2).
Figure!. Airbag Locations
The following procedures and safety precautions
must be adhered to while handling, installing and
testing airbag modules. Failure to observe these
precautions could cause the airbag to inadvertently
deploy with the risk of personal injury.
The procedures and precautionary guidelines
conform to the 'Handling and storage - The
Explosives Act 1875 & 1923' and to the 'Health and
Safety at Work Act - 1974' or local guidelines as
appropriate.
Safety Precautions and Warnings
Handling Undeployed Airbags
The electrically actuated airbag module contains
sodium azide and sodium nitrate which are
poisonous and extremely flammable substances.
Their contact with
acid,
water or heavy metals may
produce harmful, irritant gases or combustible
compounds.
The airbag module is non-serviceable and must not
be dismantled, punctured, incinerated or welded.
WARNING: Do not attempt any repairs or
electrical measurements on the airbag module.
Never measure the resistance of the airbag module,
as this may cause the airbag to deploy. Suspect
modules must be returned to Aston Martin Lagonda

Limited,
or their importer for replacement.
Tampering or mishandling can result in personal
injury.
Keep away from heat, sparks and open flames. Do
not store at temperatures exceeding 93°C (200°F).
Keep away from electrical equipment as electrical
contact may cause ignition.
Do not drop or impact the airbag module. Always
position the module 'cover-up'.
Ensure that the module connector is protected to
prevent damage. Never carry the airbag module by
the wires or connector.
Store modules in a secure lockable cabinet.
Never position material over the undeployed
module which could be projected and cause injury
in the event of inadvertent deployment.
Do not wrap arms around the module when carrying
and always carry the module with the cover and
vents facing away from the body to avoid personal
injury in the event of inadvertent deployment.
The chemical propellant mixture deploying the
airbag is a solid and therefore inhalation exposure
is unlikely even if the module is ruptured without
deployment.
As far as practical, avoid skin contact
with,
or
ingestion of, the materials present after combustion.
Exposure to high concentrations of propellant
mixture may cause headache, nausea, blurred

vision,
faintness, cyanosis, lowering of blood
pressure, tachycardia and shortness of breath.
WARNING: Sodium azide has been listed as an
'Extraordinary Hazardous Substance or
Carcinogen' by the state of
Massachusetts,
USA.
Sodium azide has been listed on the
'Right
to Know
Hazardous Substance
List'
by the state of New
Jersey and is also regarded as a 'Special Health
Hazard Substance' by the state. The propellant
mixture is sensitive to premature ignition by
electrical sources if not properly protected and
isolated.
September 1996 6-69

^=2?
Electrics
Airbag System
Eye Protection
Chemical protective goggles are recommended
where there is a possibility of eye contact with the
propellant. Safety glasses with side shields are
recommended for all other operations.
Protective Clothing
Approved protective gloves, overalls and shoes/
boots should be worn.
Handling and Storage Precautions
Do not store airbag modules near live electrical
equipment or circuitry. Store in a dry environment
at ambient temperatures.
Good housekeeping and engineering practices
should be employed to prevent the generation and
accumulation of
dusts.
Store in compliance with all
local state and federal regulations.
Driver and Passenger Airbag Modules
Assembly/Removal/Service Instructions
WARNING: In the event of a vehicle impact where the
airbags and the seatbeltpretensioner (if fitted) are
deployed, the following actions MUST be
performed:
Check the condition of the seatbelts, steering

wheel,
steering column, all connections to airbags,
and the column switchgear connectors for integrity
and damage. If in any
doubt,
replace suspected
parts for new parts.
Replace both crash
sensors,
the
safing sensor
and
the seatbelt pretensioner module (if fitted).
On completion of all repair procedures, switch on
the ignition and check that the
Airbag/SRS
warning
light comes on when the ignition is switched on
and extinguishes after approximately six seconds
indicating satisfactory completion of the airbag
and pretensioner
system
self
tests.

WARNING: Before starting
work,
ensure
that the ignition
switch is in position 'O' and the ignition key is

removed.
Disconnect the battery negative lead
within 12 seconds of switching off the ignition to
prevent the alarm system triggering.
As the airbag control module is equipped with a
back-up power source and due to the risk of the
airbag being inadvertently deployed, wait one
minute or longer after disconnecting the battery
before starting work on the airbag module.
• Disconnectingthe battery negative cable cancels
the memory for the 'one-touch' window down
system and stops the vehicle clock. Reset the
window memory and the clock when work is

completed.

• Never use airbags from other vehicles, always
use new parts.
• After work is completed, reconnect the battery
and perform the airbag warning light check
• Never use electrical probes to check voltage or
electrical resistance of the airbag modules.
• Disconnect the airbag before carrying out any
work on, or in the vicinity of the module, or
when using electric welding equipment.
• Always ensure that the battery negative lead has
been disconnected for at least one minute before
commencing any removal procedure.
September 1996 6-71

^^
Electrics
Airbag System
WARNING: Make the battery connections
last.

The airbag will deploy as the battery connections are made.
Minimum 10 Metres (33 Feet)-
7. Pass the cut ends of the two 10 metre (33ft) link
wires through an open window and connect using
two scotchlocks to the feed and return wires for one

airbag.

8. Closethe vehicle doors and leave the window with
the link wires open.
9. Check that no personnel are in the car or in the area
around the car. Warn personnel in adjacent areas
of the impending airbag deployment.

10.
Move back 10 metres (33ft) and connect the link
harness crocodile clips to the positive and negative
terminals ofthe slave battery; the airbag will deploy
immediately.

11.
Allow the deployed unit to cool for at least 20
minutes and monitor continuously to ensure that
the heat generated during deployment does not
create a fire with spilled liquids or other debris.

12.
Using all appropriate safety precautions (see all
warnings and precautions after the 'Safety
Precautions and Warnings' Heading), enter the
vehicle and cut the link harness wires from the
deployed airbag.

13.
Usingtwonewscotchlocks,connectthelinkharness
to the feed and return wires for the second airbag
and deploy it by repeating steps 7 to 11 of this
procedure.

14.
The vehicle may now be scrapped in the normal
manner with thedeployed airbag modules installed.

15.
In the event of any problems or queries, contact
Aston Martin Lagonda Limited - Technical Services
Department.
Scrapping Vehicles
Air bags

with Deployed

when scrapping a vehicle with a deployed airbag,
first check that all installed airbags have been
deployed or removed.
In the eventthatonly one airbag has beendeployed,
it must be assumed thatthe second airbag is still live
and therefore must be treated using the 'Scrapping
Vehicles with Live Airbags' procedure.
when it is verified that both airbags have been
deployed or removed, the vehicle may
be
scrapped
in the normal manner.
September 1996 6-73

Electrics
Airbag System E:m3^2?
Disposal of Live Airbags
Modu
les
removed/renewed by Aston Martin dealers
are to be deployed using the following procedure.
WARNING: Never use a customer's vehicle to
deploy airbags.
Equipment Required:
Link harness

'Slave'
battery
Safety goggles to BS 2092 grade 2 or equivalent
Rubber gloves to PrEN 374 class 2 or equivalent
Ear protectors
Particulate respirator to EN 149 grade FFP 25
Deployment cage
Note: If you do not
have access
to a deployment
cage,

please
contact Aston Martin
Lagonda
Limited
Technical

Support Department for advice.
Procedure
This procedure must be performed outdoors, away
from other personnel.
Remove any loose debris from around the airbag
and ensure that no flammable liquids are present.
Assemble the disposal cabinet and fit the airbag as
shown in figure 1 in line with the following
procedures:
a) Remove the mesh guard from the rig frame.
b) Attach the guard to the frame by bolting the
hinges to the frame.
c) Ensure the relevant plate is fitted and rotate into

position.

d) Fit and secure the airbag module onto the plate.
e) Clamp the plate down using the two toggle
clamps.
f) Close the mesh guard.
Note: The harness connected between the driver's
airbag and
the
connector
has
one red
feed
wire and one
grey/orange return wire. The harness connected between
the
passenger's
airbag and the connector
has
one blue/
orange feed wire and one pink/black return wire.
Connect the 10 metre {33ft) link harness to the

airbag.

Ensure that no personnel are in the vicinity of the
cabinet.
5. Move 10 metres (33ft) and connect the link harness
crocodile clips to the 'slave' battery; the airbag will
deploy immediately.
6. Allow the unit to cool for at least 20 minutes.
7. Open the mesh guard and remove the deployed
airbag module.
Note: Should the
design
of your deployment
cage
differ
from that described above, please contact the cage
manufacturer for advice on mounting the airbag.
8. Seal the deployed module into a plastic bag ready
for disposal.
9. In the event of any problems or queries, contact
Aston Martin Lagonda Limited -Technical Services
Department.
Disposal of Deployed Airbags
Deployed airbags are to be disposed of as special
waste and disposal must comply with local
environmental requirements. If
in
any doubt, contact
the local authority for disposal instructions.
Note; The storage, transportation, disposal and/or
recycling of airbag module components must be
performed in accordance with all applicable federal,

state
and local regulations including, but not limited to,

those
governing building and fire
codes,
environmental
protection, occupational health and safety and
transportation.
Modules removed and deployed by Aston Martin
Dealers are to be returned to Aston Martin Lagonda
Limited for disposal following prior consultation.
6-74 September 1996

Electrics
Airbag System '=2?
Airbag System Diagnostics
System Description
The airbag system installation comprises:
Airbag Diagnostic Module
Driver and passenger airbag modules
Two front impact (crash) sensors
One 'safing' sensor
Dedicated wiring harness
SRS indicator/warning lamp
The system is designed to provide protection for
both driver and front seat passenger by automatical ly
deploying airbags in the event of
a
collision during
forward travel.
In the event of a collision, the crash and safing
sensors will operate, completing the firing circuit
and causing the airbags to inflate within 32
milliseconds. At least one crash sensor and the
safing sensor must operate to fire the airbags.
Any faults in system components, installation or
wiring will be indicated by a flashing code on the
SRS/AIRBAG warning lamp. Fault code information
may also be monitored using the PDU or scan
tool.

Component Descriptions
Airbag Diagnostic Module
The airbag diagnostic module is mounted on top of
the passenger airbag mountingcage.Thediagnostic
module contains the microprocessor which is
connected to the complete airbag system. The state
of the three system sensors, the two airbag modules
and the wiring harness is constantly monitored by
the microprocessor for faults and for sensor
activation (crash) conditions.
The diagnostic module also confirms correct supply
voltage by comparing
a
direct battery voltage input
with a similar input via the ignition switch.
The diagnostic module contains a reserve power
supply, enabling the airbags to fire even if the
supply voltage is lost due to collision damage. The
reserve power charge will be retained for
approximately one minute if the positive battery
supply is lost in a collision. An auxiliary internal
circuit known as the 'dwell enhancer' provides a
temporary ground if normal system ground was lost
in a collision.
Wiring Harness
A dedicated electrical wiring harness is used to
connect all system components to the bulkhead
harness. To allow free movement of the steering
mechanism, a cable reel cassette is used to connect
the drivers airbag in the steering wheel to the airbag
harness on the steering column.
Airbag Modules
The two airbag modules contain achargeof sodium
azide/copper oxide which wi
11
generate
a
sufficient
volume of nitrogen gas to fully inflate the airbag
when ignited by an electrical impulse. The volume
of gas is greater in the passenger side airbag due to
its larger size.
Both airbag modules, including the surrounding
trim of the drivers airbag, are non-serviceable and
once deployed, must be renewed as a complete
assembly.
Crash and Safing Sensors
The two crash sensors are mounted one at either
side of the bumper mounting cross member, outside
of the bonnet hinges.
The safing sensor is mounted in the base of the
drivers side 'A' post.
The two crash sensors and the safing sensor
determine when airbag deployment is necessary in
a crash condition.
The sensor contacts will only close when the vehicle
suffers a forward impact of sufficient force. At least
one crash sensor and the safing sensor contacts
must close before the airbags will deploy. The
doubletrigger strategy
is
used to prevent deployment
during trivial impacts such as contacts during

parking.

6-78 September 1996

Electrics
Airbag System ^2?

6.4.21.4
Airbag Disarming/Arming
Procedures
WARNINGS AND CAUTIONS:
WARNINGS:
Disarm the airbags by disconnecting the battery
ground (black)
lead,
waiting one minute and then
removing the airbag modules before servicing of
any airbag or steering column component.
After disconnecting the battery ground
lead,
allow
a minimum of one minute delay for the back-up
power supply to discharge before servicing the
airbag system.
The system components are non-serviceable, if
faults are
suspected,
change components for new
items
only.

Failure to observe the above procedures may
result in accidental deployment of the airbags.
Always wear safety
glasses
when working on airbag
equipped vehicles.
Personnel carrying an airbag module must ensure
that the module and trim cover are pointing away
from the
body.
When positioning on a bench or
work surface, ensure that the airbag module and
trim cover face upwards to limit motion on
accidental deployment.
Always wear
gloves
when handling deployed airbag
modules. Deposits of sodium hydroxide may be
presenton the module surface. If sodium hydroxide
contacts any area of the skin, wash the affected
area immediately with mild soap and
water.

Dispose of the deployed airbag using the correct
procedures referred to in this section.
Cautions:
When scrapping vehicles,
ensure
that the
airbags
have
been deployed (see
Scrapping Vehicles
with Live
Airbags).

If a component
has been
renewed and the fault
does
not

clear,
refit the original item and repeat the diagnostic
procedure.
After
servicing,
repeatthe diagnostic
procedures
to ensure
correct
system
operation.

Renew
the airbag module if the surrounding trim
panels

are
damaged.
Do not attempt to repaint trim covers as
paint may
damage
cover material.
Disarming the Airbags
3.
4.
WARNING: Carry out the following disarming
procedure before attempting any work on the
vehicles electrical
systems.

Note: The battery ground (black) lead must be
disconnected within 12 seconds of switching off the
ignition to avoid the alarm siren sounding.
Disconnect the battery ground
lead.
Allow a
minimum of one minute delay for the back-up
power supply to discharge.
Remove the drivers side airbag module and replace
it with an airbag simulatorfrom the simulator kit (Pt

No.
43.27028).
Remove the passengers airbag module and replace
it with an airbag simulator from the simulator kit.
Reconnect the battery ground.
Rearming the Airbags
WARNING: Carry out the following procedure to
rearm and check the airbags after completing all
work on the vehicles electrical
systems.

Note: The vehicle battery
must be
disconnected within
12
seconds
of switching off
the
ignition
to
avoid the alarm
siren sounding.
^. Disconnect the battery ground
lead.
Allow a
minimum of one minute delay for the back-up
power supply to discharge.

2.
Removethedriverssideairbagsimulatorand replace
it with the drivers airbag module. Secure the airbag
module with the two captive torx screws.
3. Remove the passengers side airbag simulator and
replace it with the passenger side airbag module.
Secure the module with four nuts and washers.
Close the passenger side airbag door.

4.
Reconnect the battery ground.
5. Switch on the ignition and check for correct
indications from the SRS/AIRBAG warning light.
TheSRS/AIRBAC lamp should come on after
a
brief
delay and remain on for approximately six seconds
during the airbag system self check. The lamp will
extinguish upon satisfactory completion of the self
check, or will flash a diagnostic code if an airbag
system fault is detected. Continuous illumination of
the warning lamp may indicate a seatbelt
pretensioner fault
Note:
Reset the
clock and window
ECUs
on completion.
6-80 September 1996

"^p
Electrics
Airbag System
No Airbag Warning Lamp

I
noperative lamp, lamp ci rcu it or no ign ition voltage
to the diagnostics module
Normal Operation
The airbag warning lamp is designed to illuminate
for approximately six seconds when the ignition is
switched
on.
This period
is
allocated for satisfactory
performance of the airbag system self test.
Note: The a irbag warning lamp is
driven
by
the instrument

pack and not directly by the airbag diagnostic module.
The airbag diagnostic module requires an ignition
supply to pin
1
to energise the airbag warning lamp
circuit. If the warning lamp circuit is open, or the
diagnostic module does not receive an ignition
voltageatpini, the warning lamp will not illuminate.
Open circuit in the warning lamp supply, in
conjunction with another system fault, will cause
the diagnostic module to emit five tones every 30
minutes while the ignition is switched on. Repair
the faulty circuit before further diagnosis.
Note:
The
diagnostic module will not emit
the
five tone
signal if the warning lamp
is
open circuit and
there
is no

system
fault.

Possible Causes
Defective airbag warning lamp
Faulty wiring in the airbag warning lamp circuit
Loss of ignition voltage at diagnostic module pin 1.
Loss of ground at diagnostic module pin 3
Instrument pack fault
Fault Analysis
WARNING: Read and adhere to all warnings and
safety procedures at the start of this section when
working on the airbag
systent.

1.
Remove the instrument pack and check the airbag
warning lamp.
If the lamp is good, go to step 2.
If the lamp is defective, replace it, switch on the
ignition and check that the lamp is now on for
approximately six seconds after ignition on.

2.
Disarm the airbag system and fit airbag simulators
(6.4.21.4).
9.
Connect the PDU. Switch on the ignition. Measure
the 12V ignition supply voltage from airbag
diagnostic connector pin
1 -1
{+) to chassis ground.
If ignition voltage is present, go to step 6. If ignition
voltage is not present, go to step 4.
Checkfuse F15passengersidefuseboxRHDorF17
passenger side fusebox LHD (Ignition supply to the
diagnostic module pin
1
-1). If the fuse is good, go
to step 5. If the fuse is replaced, go to step 6.
Check for an open circuit on the YW wire from fuse
F15 passenger sidefusebox(F17 LHD)todiagnostic
module pin 1-1. If continuity is good, isolate the
fault in the 12V supply to fuse Fl 5 (Fl 7) and then
go to step 9.
Measure the voltage from diagnostic module pin
1
-
1 to diagnostic module pin 1-3. If 12V is not
present, isolate and service the open circuit in the
diagnostic module ground to pin 1-3. Then go to
step 7.
Switch the ignition off. Set up to measure the
voltage from DM pin
1
-4 to DM pin
1
-5 during the
first six seconds after ignition on.
Switch on the ignition, the warning light signal to
the instrument pack should switch for six seconds
after a brief delay.
If the signal does not switch, the diagnostic module

is
fau Ity. Replace the modu
le,
switch on the ign ition
and check that the airbag warning lamp does light
for six seconds after ignition on.
If the signal does switch for approx. six seconds
after ignition on, the fault is in the instrument pack
or wiring, go to step 8.
Check continuity of the YW wire from diagnostic
module pin
1
-4 to instrument pack 16 way plug pin

2.

If continuity is good, service the instrument pack
and then retesttoensure correct indication from the
airbag warning lamp at ignition on.
If continuity is defective, service the wire and then
retest to ensure correct indication from the airbag
warning lamp at ignition on.
Disconnect the PDU, and rearm the airbags
(6.4.21.4). Switch on the ignition and check for
correct indications from the airbag warning lamp.
September 1996 6-83