1997 ASTON MARTIN DB7 ignition

'=2?
Electrics
Airbag System
4.5.01.3 Driver's Airbag Module Renew
Read and adhere to all warnings and safety
procedures quoted at the start of this section when
working on airbag modules.

1.
Ensure that the steering system is centralised and
that the steering wheel is in the lowest tilt position.

2.
Disconnect the vehicle battery and insulate the
battery lead to avoid accidental reconnection. Wait
for at least one minute before proceeding with work
on the removal of the airbag.
Hote: The vehicle battery
must be
disconnected within
12 seconds of switching off
the
ignition to avoid the alarm
siren sounding.
5. Carefully remove the module from the steering
wheel and disconnect the airbag module multi-

plug.

6. To ensure personal safety, double check that the
battery is still disconnected and the battery lead
safely insulated. Connect the new airbag module

multi-plug.
Fit and align the new module to the
steering wheel and tighten the two securing torx
screws. Return the steering to the straight ahead

position.

7. Remove the battery lead insulation and reconnect
the battery
lead.

Note:
The vehicle
clockandthe window control unitwill
need
resetting
after completion of
this
procedure.
8. Switch on the ignition and check that the airbag
warni ng
I
ight comes on when the ignition is switched
on and extinguishes after approximately sixseconds
indicating satisfactory completion of the airbag
system self tests.
Insert the ignition key and turn to position I. Turn
the steering wheel to the left, 90° from its straight
ahead position, and loosen thefirstmoduiesecuring
torx screw.
Turn the steering wheehSO" to the rightand loosen
the second module securing torx screw.
September 1996 6-75

Electrics
Airbag System ^^?

7.8.02.6

Renew
Passenger's Airbag Module
Read and adhere to all warnings and safety
procedures quoted at the start of this section when
working on airbag modules.
Disconnect the battery and wait for at least one
minute before proceeding with the airbag removal.
Note:
The
vehicle battery
must
be disconnected within
12
seconds
of switchingoff
the
ignition
to
avoid the alarm
siren sounding.
2. Open the passenger airbag deployment door.
3. Release four nuts and remove the airbag module.

4.
Disconnect the airbag harness multi-plug.
5. Connect and fit the new module and secure with
four nuts.
6. Refit the airbag deployment door.
Note:
The vehicle
clock and
the
window control unit will
need
resetting
after completion of
this
procedure.
7. Reconnect the battery. Switch on the ignition and
check that the airbag warning
I
ight comes on when
the ignition is switched on and extinguishes after
approximately six seconds indicating satisfactory
completion of the airbag system self tests.
6.1.23.1/6.2.10.1 Airbag
Crash
Sensors
Renew
Read and adhere to all warnings and safety
procedures quoted at the start of this section when
working on the airbag system.

1.
Disconnect the battery and wait for at least one
minute before working on the airbag system.
Note: The vehicle
battery
must be disconnected within
12
seconds
of switchingoff
the
ignition
to
avoid thealarm
siren sounding.

4.

5.
Raisethevehicleon a rampand remove the relevant
front roadwheel and wheel arch liner.
Disconnect the sensor connector and feed the
protected loom forward through the body aperture.
Open the bonnet and release two bolts securing the
crash sensor to the body.
Fit and secure the new sensor and feed the sensor
loom back through the body aperture.
Reconnect the sensor. Refit the wheel arch liner
and the roadwheel.
Note:
The vehicle
clock and
the
window control unit will
need
resetting
after completion of
this
procedure.
Reconnect the battery, switch on the ignition and
check that the airbag warning
I
ight comes on when
the ignition is switched on and extinguishes after
approximately six seconds indicating satisfactory
completion of the airbag system self tests.
6-76 September 1996

^7
Electrics
Airbag System

6.4.21.2
Airbag 'Safing' Sensor Renew
Read and adhere to all warnings and safety
procedures quoted at the start of this section when
working on the airbag system.

1.
Disconnect the battery and wait for at least one
minute before working on the airbag system.
Note:
The
vehicle battery must be disconnected within
12 secondsofswitchingoffthe ignition to avoid the alarm
siren sounding.
^h
Note: RH drive shown,
the safing sensor is
always
on
the drivers side
of the car
2. Open the drivers door and remove the lower 'A'
post
trim.

3. Release two screws retaining the airbag safing
sensor.

4.
Disconnect and remove the airbag safing sensor.
5. Connectand securethe replacement sensor. Replace
the 'A' post
trim.

Note:
The
vehicle clock and
the
window control unit will
need
resetting
after completion of
this
procedure.
6. Reconnect the battery, switch on the ignition and
check that the airbag warning
I
ight comes on when
the ignition is switched on and extinguishes after
approximately six seconds indicating satisfactory
completion of the airbag system self tests.

6.4.21.1

Renew
Airbag Diagnostic Module

1.

2.

3.

4.

6.
7.
Read and adhere to all warnings and safety
procedures quoted at the start of this section when
working on the airbag system.
Disconnect the battery and wait for at least one
minute before working on the airbag system.
Note: The vehicle battery must
be
disconnected within
l2secondsofswitchingofftheignitiontoavoidthealarm

siren
sounding.
Disarm the airbags (6.4.21.4).
Remove the facia assembly.
Note: RH drive shown,
diagnostic module always on

passengers
side of
the
car
Disconnect the airbag control module (Fig 1-1).
Release the module from the top of the airbag
carrier assembly and remove the module.
Refit and secure the replacement airbag control
module and connect the harness connector.
Refit the facia assembly.
Rearm the airbags (6.4.21.4).
Note:
The
vehicle clock and
the
window control unit will
need
resetting
after completion of this procedure.
September 1996 6-77

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

^=2?
Electrics
Airbag System
Airbag Diagnostic Module Fault Codes
Fault codes may be extracted in one of two ways:
Through the upper diagnostics connector using the PDU, or as a series of flashes of the SRS/AIRBAG warning lamp.
Each series of flashes represents a two digit number, representing a fault code from the list below which is recorded
in priority order (i.e. If two faults are present, the code nearest the top of the list will flash. Clear the first code, then
the second code will flash). Fault analysis procedures for each code are included on the following pages.
_ No Airbag warning lamp - Inoperative airbag warning lamp or no ignition voltage to the diagnostic module
Continuous airbag warning lamp- Diagnostic module disconnected or inoperative, or a seatbelt pretensioner
fault (see pretensioner diagnostics).
12 Low battery voltage
13 Airbag circuit shorted to ground
14 Front crash sensor circuit shorted to ground
21 Safing sensor incorrectly mounted in the vehicle
22 Safing sensor output circuit shorted to battery voltage
23 Safing sensor input feed/return open circuit
24 Safing sensor output feed/return open circuit
32 Drivers side airbag circuit high resistance or open circuit
33 Passengers side airbag circuit high resistance or open circuit
34 Drivers side airbag circuit low resistance or short circuit to ground
35 Passenger side airbag circuit low resistance or short circuit to ground
41 Front right crash sensor feed/return open circuit
42 Front left crash sensor feed/return open circuit
44 Front right crash sensor incorrectly mounted on the vehicle
45 Front left crash sensor incorrectly mounted on the vehicle
51 Diagnostic module internal fuse intermittent or short circuit to ground
52 Back-up power supply - overvoltage fault
53 Front crash sensor circuits resistance to ground or internal diagnostic module failure
Rapid continuous flashing of the airbag lamp (no fault code)- all front crash sensors disconnected
September 1996 6-81

Electrics
Airbag System ^^?
Airbag Diagnostic Module Connector
The wiring to the airbag diagnostic module passes through two plugs into a single socket. Plug
1
is grey coloured,
plug 2 is black. To aid in fault analysis, the diagnostic module connector pins for plugs
1
and 2, and their functions
are listed below:
Connector 1 - Grey Colour
Pin No. Colour Circuit
Connector 2 - Black
Pin No. Colour Circuit
1-1
1-2
1-3
1-4
1-5
1-6
1-7
1-8
1-9
1-10
1-11
1-12
LGS
ON
B
YW
B
YU
RW
-
RN
RG
KU
KG
12V Ignition Supply
RH Crash Sensor Monitor
Ground
Airbag Warning Lamp Output
Ground
LH Crash Sensor Monitor
12V Battery Power
Not Used
Safing Sensor Input
Safing Sensor Ground Monitor
RH Crash Sensor Feed
LH Crash Sensor Feed
2-1
2-2
2-3
2-4
2-5
2-6
2-7
2-8
2-9
2-10
2-11
2-12
-
RP
KP
KN
RP
YG
-
OP
ow
-
YP
-
Not Used
Passenger Airbag Module Feed
Passenger Airbag Module Return
Drivers Airbag Module Return
Drivers Airbag Module Feed
Safing Sensor Output Monitor
Not Used
LH Crash Sensor Ground Monitor
RH Crash Sensor Ground Monitor
Not Used
Safing Sensor Feed
Test Input
Plug 2 Piugl
/LrLrLruuTJu—LrLrLrLrLrLnj
OOO
Connector 2/12-Way/Black
YG RP 3 KP

mn

10 9 OW
Connector 1/12-Way/Grey
6 YU 5 B
12 KG 11 KU 10 RG
4 YW
I
ON LGS
0
6
12 'I J'
6
12 J
6-82 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