battery ASTON MARTIN DB7 1997 Owner's Manual
Page 193 of 421
^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  
Page 194 of 421
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  
Page 196 of 421
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  
Page 197 of 421
^=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  
Page 198 of 421
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  
Page 200 of 421
Electrics 
Airbag System [EE:^^^? 
Continuous Airbag Warning Lamp 
Inoperative lamp circuit or no ignition supply to the 
airbag diagnostic module. 
Normal Operation 
The airbag warning lamp is designed to illuminate 
for approximately six seconds when the ignition is 
switched
 on.
 This period isallocated for satisfactory 
performance of the airbag system self test. If after 
this period, the diagnostic module detects a fault 
within the system, the airbag warning lamp will 
begin to flash. 
Note:
 The seat
 belt
 pretensioner system
 (if fitted)
 shares 
the
 airbag/SRS
 warning lamp with
 the airbag
 system.
 If a 
seat belt pretensioner fault is
 detected,
 the
 Airbag/SRS 
warning lamp will be permanently illuminated. Ensure 
thata permanently lit
 lamp
 is nottheresultof a pretensioner 
fault before carrying out fault analysis on the airbag 
system. 
Poor connection or disconnection of the diagnostic 
module harness may cause a short circuit from DM 
pin 4 (warning lamp control) to pin 5 (ground) and 
cause permanent illumination ofthe warning lamp. 
Faulty operation of the diagnostic module internal 
logic may fail to turn off the warning lamp control 
circuit and cause constant illumination of the 
warning lamp. 
Fault Analysis 
WARNING: Read and adhere to all warnings and 
safety procedures at the start of this section when 
working on the airbag system. 
1.
 Disarm the airbag system and fit airbag simulators 
(6.4.21.4). Reconnect the battery. 
2.
 Inspectthe instrument pack and diagnostic module 
connectors for damaged, pushed out pins, proper 
location etc. 
If any defects are identified, service as necessary. 
Retest to ensure correct operation of the airbag 
warning light. 
If the connector condition and security are good, 
reconnect the connectors and go to step 3. 
5. 
Connect the PDU to the upper diagnostic socket 
and monitorthe airbag warning lamp
 signal.
 Switch 
on the ignition. 
If the signal is permanently low, suspect a short 
circuit to ground on the airbag warning lamp 
control line within the diagnostic module or from 
diagnostic module pin
 1
 -4 to earth. Co to step 4. 
If the signal switches low for six seconds after 
ignition on but the airbag warning lamp is 
permanently illuminated, suspect a fault in the 
output side of the instrument pack to the airbag 
warning lamp. 
Disconnect diagnostic module plug 1 (slate) and 
withdraw the plastic locking wedge to prevent 
shorts to other circuits. Check continuity from pin 
1-1 to ground. 
If a short circuit to ground is detected, service the 
wiring
 as
 necessary. Replacethe locking
 wedge,
 re
insert the connector. Switch on the ignition and 
check that the airbag warning lamp signal atpin 1-
4 goes high six seconds after switching on the 
ignition and that the warning lamp extinguishes. 
If no short circuitto ground isdetected,thediagnostic 
module is faulty. Replace the diagnostic module. 
Switch on the ignition and check that the airbag 
warning lamp signal at pin
 1
 -4 goes high six seconds 
after switching on the ignition and that the warning 
lamp extinguishes. 
Switch off the ignition. Disconnect the battery. 
Rearm the airbags (6.4.21.4). Switch on the
 ign
 ition 
and check for correct indications from the airbag 
warning lamp. 
6-84 September 1996  
Page 201 of 421
^^? 
Electrics 
Airbag System 
Airbag DM Fault Code 12 
Low battery voltage 
Normal Operation 
The airbag diagnostic module (DM) monitors the 
voltage at pin 1-7 which should be equal to the 
battery voltage. If a voltage lower than 9 volts is 
detected at pin 1-7, the airbag warning lamp will be 
illuminated and fault code 12 will be flashed. 
Possible Causes 
Drop in battery voltage to DM pin 1-7 caused by: 
• Open circuit to pin
 1
 -7 from the battery 
• Short circuit to ground on the battery feed 
circuit 
• Safing sensor feed shorted to ground 
• Safing sensor internal short to ground 
• Faulty charge system draining the battery 
Fault Analysis 
WARNING: Read and adhere to all warnings and 
safety procedures at the start of
 this
 section when 
working on the airbag system. 
1.
 Complete a battery voltage test as follows: 
a) Measure the battery voltage at the battery under 
KOEO and KOER conditions. 
If the battery voltage is below 10.5 volts during 
KOEO or below 12.5 volts during the KOER tests, 
service the battery
 and
 charging system
 as
 necessary. 
Retest for airbag system fau
 It
 code 12 and go to step 
2 if the fault recurs. 
2.
 Complete a 12 volts supply check at the diagnostic 
module: 
a) Disarm the airbag system and fit airbag simulators 
(6.4.21.4) 
b) Disconnect the airbag diagnostic module. 
c) Switch on the ignition. 
d) Measurethevoltagebetween DM hamessconnector 
pin 1-7 (+) and harness connector pin 1-3 (-). 
e) If battery voltage is not present, go to step 3. 
If battery voltage is present at pin 1-7, renew the 
diagnostic module. Rearm and verify the airbag 
system. 
3. Check the supply fuse as follows: 
a) Check fuse F16 in the passenger side fusebox RHD 
(or F18 in passenger fusebox LHD). 
If the fuse has not blown, check for an open circuit 
between battery positive and diagnostic module 
connector pin
 1
 -7. 
If the fuse has blown. Renew the fuse and/or repair 
the wiring and go to step 4. 
4.
 Check for a short circuit as follows: 
a) Switch off the ignition. With the airbag diagnostic 
module disconnected, measure the continuity to 
earth from diagnostic module connector pin
 1
 -7 to 
ground. 
If no short circuit is detected, go to step 5. 
Ifashortto ground isdetected, service the wiring as 
necessary. Reconnect the diagnostic module and 
retest to ensure that code 12 is cleared. 
5. Check for a short circuit to ground on the safing 
sensor wiring as follows: 
a) Check for a short circuit to ground at diagnostic 
module pin 1-9. 
b) If a short is detected, disconnect the safing sensor 
and repeat the check at diagnostic module pin
 1
 -9. 
If a short is still detected, service the wiring from 
diagnostic module pin
 1
 -9 to safing sensor pin 7. 
c) If no short circuit is detected, change the airbag 
diagnostic module. Reconnect the diagnostic 
module and retest to ensure that code 12 does not 
recur. 
6. Rearm the airbags (6.4.21.4) 
September 1996 6-85  
Page 203 of 421
mxm^^^? 
Electrics 
Airbag System 
Airbag DM Fault Code 14 
Primary crash sensor circuit short to ground 
Airbag DM Fault Code 21 
Safing sensor insecure mounting. 
Normal Operation 
The diagnostic module measuresthevoltage at pins 
1
 -2 and
 1
 -6. The normal voltage at these pins is 10 
volts (±1 volt) with the ignition on, and battery 
voltage with the ignition off. 
If the voltage at the airbag diagnostic module 
connector pins
 1
 -2 or
 1
 -6 drops below 5 volts, fault 
code 14 will be generated and the airbag warning 
lamp will be switched on. When generating a code 
14 the diagnostic module also generates a signal to 
blow its own internal thermal fuse. This action 
disables the airbag deployment circuit. The airbag 
diagnostic module fuse is non-repairable and the 
module must be replaced after removing the short 
circuit. If the voltage at pins 1-2 and 1-6 returns to 
normal,
 fault code 51 (blown thermal fuse) will be 
logged. 
Fault Analysis 
WARNING: Read and adhere to all warnings and 
safety procedures at the start of
 this
 section when 
working on the airbag system. 
1.
 Disarm the airbag system and fit airbag simulators 
(6.4.21.4) 
2.
 Disconnect the airbag diagnostic module and 
remove the plastic wedge from plug
 1
 (slate). 
Note:
 The
 plastic wedge contains a shorting bar which 
would
 short
 together pins
 1-3
 (gnd),
 1-11
 and 1-2 when 
the plug is disconnected. 
3 Measure the continuity to ground at the following 
pins on the diagnostic module harness connector: 
1-2 RH crash sensor monitor 
1-11 LH crash sensor feed 
1
 -6 LH crash sensor monitor 
1-12 RH crash sensor feed 
If no short circuit is detected, go to step 4. 
If a short circuit
 is
 detected, disconnect the relevant 
crash sensorandrepeatthecontinuity measurement 
to isolate the circuit fault. Service the wiring or 
replace the crash sensor as necessary. Refit the 
plastic wedge to the diagnostic module connector. 
Fit a new airbag diagnostic module and rearm the 
airbags (6.4.21.4). 
Normal Operation 
The diagnostic module measures the resistance 
between pins
 1
 -10 (safing sensor case ground) and 
1-3 (monitor reference ground) at the diagnostic 
module connector. If the resistance is greater than 
2Q
 a
 fault code
 21
 will be generated and the airbag 
warning lamp will be switched on. 
Note:
 a
 good ground connection is vital.
 The
 wire from 
pin
 1-1
 is riveted to the safing
 sensor case
 and the
 case 
must
 be securely
 grounded to the vehicle
 body. 
Fault Analysis 
WARNING: Read and adhere to all warnings and 
safety procedures at the start of this section when 
working on the airbag system. 
Disarm the airbag system and fit airbag simulators 
(6.4.21.4). 
Disconnect the diagnostic connector and check for 
continuity from pin 1-3 to chassis ground. 
If continuity is good, go to step 3. 
If the resistance reading is 2Q or more, service the 
diagnostic module ground circuit to pin 1-3 as 
necessary. Confirm a good ground path between 
pins 1-10 and 1-3.Clearthecode21 and rearm the 
airbags (6.4.21.4). 
Check for continuity between pins
 1
 -10 and chassis 
ground at the safing sensor. 
If the resistance is above 2Q, check for continuity 
from the safing sensor connector pin 5 to chassis 
ground.
 Also check the safing sensor mounting for 
corrosion,
 dirt or loose fixings. Service the wiring 
and/or clean and secure the sensor mounting as 
necessary, if a satisfactory ground is not achieved, 
replace the safing sensor. 
Make
 a
 final continuity test from diagnostic module 
connector pin
 1
 -3 to
 1
 -10 to ensure a satisfactory 
ground
 path.
 Reconnect the diagnostic module. 
Clear the code
 21.
 Rearm the airbags (6.4.21.4). 
September 1996 6-87  
Page 204 of 421
Electrics 
Airbag System [D:B3-2? 
Airbag DM Fault Code 22 
Safing sensor output circuit shorted to battery 
voltage. 
Normal Operation 
The diagnostic module measures the voltage at pin 
2-5 (airbag module feed) and 2-5 (safing sensor 
output monitor) at thediagnosticmoduleconnector. 
The voltage at these pins is dependant on charging 
system voltage as shown in the table below. If the 
voltage at either pin exceeds 5 volts,
 a
 fault code 22 
will be generated. 
in 2-5 
2.3V 
2.4V 
2.5V 
2.7V 
2.8V 
3.0V 
3.1V 
3.2V 
3.4 V 
3.5V 
3.7V 
3.8V 
4.0V 
4.1V 
4.3V 
Pin 2-6 
2.3V 
2.4V 
2.5V 
2.7V 
2.8V 
3.0V 
3.1V 
3.2 V 
3.4 V 
3.5V 
3.7V 
3.8V 
4.0V 
4.1V 
4.3V 
Charge Volts 
9.0V 
9.5V 
10.0V 
10.5V 
11.0V 
11.5V 
12.0V 
12.5V 
13.0V 
13.5V 
14.0V 
14.5V 
15.0V 
15.5V 
16.0V 
Possible Causes 
• A short between pins 2-5 or 2-6 and another 
wire.
 (The wiring to the safing sensor carries 
voltages above 5 volts). 
• A short between the cable reel cassette circuit 
and other 12 volt circu its at the steering column 
head. 
• A short across the normal ly open contacts of the 
safmg sensor. 
• Vehiclechargingsystem voltage too
 high.
 If the 
generator output is greater than 17V, fault code 
22 may be logged. 
Fault Analysis 
WARNING: Read and adhere to all warnings and 
safety procedures at the start of this section when 
working on the airbag system. 
Disarm the airbag system and fit airbag simulators 
(6.4.21.4). 
Check the voltage at the battery with the engine 
running at approximately 1500 rpm. 
If the voltage is 14.8 ±0.5 volts, the charging 
voltage is within specification, go to step 3. 
If the voltage is significantly above 14.8 volts (the 
voltage regulator set point) service the charging 
system.
 Clear the code 22. Rearm the airbags 
(6.4.21.4) 
Check in the area of the diagnostic module 
connector for harness damage which could cause 
a short circu it to 12 volts. (Note: The airbag system 
harness runs are sheathed in black plastic protection 
and harness damage is unlikely.) 
If no harness damage is evident, go to step 4. 
If harness damage is identified, service the wiring as 
necessary. Clear the code 22. Rearm the airbags 
(6.4.21.4). 
Switch on the ignition. Monitor the voltage at pins 
2-5 and 2-6 whilst rotatingthe steering from lock to 
lock in both directions. 
If the voltage at both pins remains below 5.0 volts, 
go to step 5. 
If the voltage rises to above 5.0 volts, service the 
cable reel cassette or wiring as necessary. Clear the 
code 22. Rearm the airbags (6.4.21.4). 
With the ignition on, check the voltage at pins 2-5 
and 2-6 whilst manipulating the bulkhead and 
safing sensor harnesses. 
If the voltage rises above 5.0 volts, service the 
wiring fault in the harness area being manipulated 
at the time the voltage rise occurred. 
If no voltage rise occurs, fit a new safing sensor as 
the most likely cause of the code 22. Clear the code 
22 and rearm the airbags (6.4.21.4). 
6-88 September 1996  
Page 205 of 421
>^ '—-y ^ Electrics 
-^ ^ ^ Airbag System 
Airbag DM Fault Code 23 
Safing sensor input- battery feed/return open circuit. 
Normal Operation 
The diagnostic module measures the voltage on 
diagnostic module pin
 1
 -9 at all times. The voltage 
can be as high as 25 volts when the backup power 
supply is fully charged. 
Pin
 1
 -9 is connected to pin 2-11 inside the safing 
sensor and the voltage on both these pins shou
 Id
 be 
the same. If the voltage on pin 2-11 fails below the 
voltage on pin
 1
 -9, a code 23 is generated. 
Possible Causes 
• Open circuit in the wiring to diagnostic module 
pin 1-9. 
• Open circuit in the wiring to diagnostic module 
pin2-n. 
Fault Analysis 
WARNING: Read and adhere to all
 warnings
 and 
safety procedures at the start of
 this
 section when 
working on the airbag
 system. 
1.
 Disarm the airbag system and fit airbag simulators 
(6.4.21.4). 
2.
 Disconnect the diagnostic connector and thesafing 
sensor connector. Check for continuity from DM 
pi n 1
 -9 to safing sensor harness connector
 pi n
 7 and 
from DMpin 1-11 to
 safing
 sensor harness connector 
pin 6. 
If the continuity of both leads is good, go to step 3. 
If a continuity fault is detected, repair the wiring as 
necessary. Reconnect ail components. Clear the 
code 23. Rearm the airbags (6.4.21.4). 
3. Check the continuity between pins 6 and 7 of the 
safing sensor. 
If the continuity is good, replace the diagnostic 
module. Rearm the airbags (6.4.21.4). 
If a continuity fault is detected, replace the safing 
sensor. Reset the code 23. Rearm the airbags 
(6.4.21.4). 
September 1996 6-89