service indicator ASTON MARTIN DB7 1997 Workshop Manual

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

The Aston Martin Lagonda Diagnostic System
Installation Instructions
[ES^'^?

Powering-Up the Base Station
When first operating the System or when first using
a PDU fitted with substitute batteries, it will take up
to36 hourstoachievefull charge. Inthemeantime,
the PDU can be used whilst connected to the base
station or to the vehicle battery.
Vi/\RNmGS:
When using the system equipment, basic safety
precautions should always be followed, including:
Carefully read and follow all instructions.
Care should be taken as burns can occur from
touching hot parts.
Do not operate the appliance with a damaged
mains lead or if the appliance has been dropped or
damaged. Call your local GenRad Service Centre
immediately for a substitute
part.

Do not let the mains lead hang over the
edge
of the
table, bench or counter or come into contact with
hot manifolds or moving fan blades.
The Aston Martin Portable Diagnostic Unit
is
fitted with an
auto switching power supply suitable for voltage supplies
of 100 - 240 VAC 50 - 60 Hz. You need only check that
the power cord connector is of the correct type for your
power outlets.

1.
Connect the mains lead to the mains outlet.

2.
Check that the green indicator lamp above the base
station door is illuminated. If the green lamp does
not come on, see the problem solving section for
advice.
3. After a few seconds, during which the electronics
module completes its self-test, the red OK indicator
lamp should illuminate. If the red lamp does not
come on, see the problem solving section for
advice.

4.
Allow the base station electronics module to reach
working temperature. This will take approximately
BOminutes, after which time the base station will be
ready to accept the software on CD-ROM.
5. Slide the PDU into its carrying case and place the
associated cables and probes in the carrying case
compartments.
6. Place the carrying case onto the base station at the
far left side (Fig 5). This is the normal place for
charging the battery, loading software and storing
the PDU. Note that it is retained by raised retaining
blocks which fit inside the recesses under the
carrying cases (Fig 5).
7. Remove the protective coverfromthe PDU interface
panel socket (Fig
1
-7.6)
8. Usingthe PDU to base station cable (0064) connect
panel socket 6 to the base station left socket (Fig
1
-

19).
The indicator lamp will glow orange during
fast charge and yellow during trickle charging.
9. A second PDU can be fitted on the central position
on the base station and may be connected to the
right charging socket using a second cable (0064).
Note that both units may be charged simultaneously
but software may only be loaded from CD-ROM
using the left base station socket.
Figure 5. Normal PDU position
9-10 May 1996

The Aston Martin Lagonda Diagnostic System
Installation Instructions ^7
Problem Solving
CAUTION: If any part of the
system
is damaged, do not use it. Call your local GenRad Service Centre immediately for
a substitute
part.
Refer to 'Parts Ordering'.
CAUTION: With the exception of
those
parts referred to in the Servicing and Maintenance section, there are no user
serviceable parts. All servicing must be carried out by GenRad Service Centres.
PDU Self-Test
The system self test routine should be run periodically even if there are no apparent problems with the system.
Running the system self-test will identify any problems before they impact on productivity.
If it is suspected that the system is operating incorrectly, run the PDU system self test option on the main menu).
If the system self test will not run, or the PDU will not switch on, the instructions in this section must be followed
carefully.
If one of the fol lowing test steps advises you to order or fit a new part, make a note of the test step, part number and
description. Then follow the parts ordering procedure later in this section.
Stepi
Connect the mains power to the base station. Is the green base station indicator illuminated?
YES - Go to step 4
NO - Go to step 2
Step 2
Check the mains supply, then check the mains
lead.
Is
the mains lead faulty?
YES - Renew the mains
lead.

NO - Go to step 3
Step 3
Remove the electronic module from the base station.
Using a small screwdriver, open the fuse drawer below the power socket on the rear of the module (Fig 16). Remove
the fuse and fit the spare fuse. The fuse must be lEC 127 approved ceramic type 250V 2A (T). Re-install the module
into the base station, power up the system. Is the base station green indicator illuminated?
YES - The fuse was faulty
NO - Renew the electronic module (0019)
Figure 16. Electronic Module Fuse Replacement
9-16 May 1996

^^
The Aston Martin Lagonda Diagnostic System
Installation Instructions
Step 16
Observe the display screen. Is the screen displaying
either of the symbols shown in Fig 19?
YES - Remove the CD caddy and check the CD-ROM.
Re-install the CD-ROM. Go to step 13.
NO - Co to step 19
Figure 19. Reload the CD and retry
Step 17
Connect the PDU to the base station top left connector using the second PDU to base station cable (0064) (Fig 34).
Is the screen displaying the symbol shown in Fig 15?
YES - Go to step 18
NO - The first PDU to base station cable is faulty, renew the cable (0064)
Step 18
Connect the PDU to the VIA using cable (0030) and connect the VIA to the VBA using cable (0028). Connect the
VBA to a charged battery. Does the VIA panel indicator flash for more than 5 seconds after pressing the 'tick'
icon.

YES - Renew the electronic module (0019)
NO - Renew the PDU (001 7)
Step 19
Observe the screen display. Is the screen displaying the
symbol shown in Fig 20?
YES - During the data transfer, the connection was lost.
Check to see if the cable connections are intact, if not,
reconnect and go back to step 13.
NO - Go to step 20
Figure 20. Data transfer connection lost
Step 20
Observe the screen display, is the language selection
screen displayed (Fig 21)?
YES - Try to select a language, go to step 21
NO-Call your local GenRad Service Centre for advice.
(^G?) English
Figure 2
7.
Language selection screen
May 1996 9-19

The Aston Martin Lagonda Diagnostic System
Installation Instructions ^=2?
Warranty
The Aston Martin Diagnostic System is covered by a one year warranty. Should any of the electrical components
fail during the warranty period, contact your local GenRad Service Centre for a replacement part. Note that the
warranty does not include physical damage.
Spare Parts
Refer to the Aston Martin Diagnostic System Users Guide for a full parts list. All spare parts should be obtained from
your local GenRad Service Centre who can advise you on current prices.
Servicing and Maintenance
CA UTION: With the exception of those parts listed in this section, there are no user serviceable parts within the
system. All servicing must be carried out by GenRad Service Centres.
Battery Testing.
The NICAD batteries fitted in the PDU are designed to be rechargeable and should normally last through many
recharge cycles. Battery life of three to five years can be expected. The capacity of new batteries improves after
several charging cycles. After extended use, they may require renewing. The following procedure will assist you to
determine when renewal is required. Do not use this procedure with new batteries or with a new PDU.
Testing Procedure

1.
Remove all cables from the PDU.

2.
Switch the PDU on and leave it until it switches off (the power on indicator will extinguish)
3. Connect the PDU to the base station for at least 12 hours charging.

4.
Remove all cables from the PDU, switch on the PDU and start timing.
5. If the PDU switches off in less than 30 minutes, the batteries should be renewed.
Changing the Battery Pack
CAUTION: Always read and follow safety warnings and instructions printed on the equipment. The rechargeable
NICAD batteries fitted to the PDU are of a special type. They must only be substituted by GenRad approved parts.
Do not substitute the batteries with any other type. Always dispose of old batteries in compliance with local
recycling regulations.
Battery Changing Procedure
A spare battery pack kit (0975) is available from your local GenRad Service Centre.
Figure 23. Battery cover screw Figure 24. Battery pack
9-22 May 1996