service ASTON MARTIN DB7 1997 User Guide

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

^^?
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

Electrics
Airbag System ^2?
Airbag DM Fault Code 13
Airbag circuit short to ground
Normal Operation
The diagnostic modu
le
measures the voltage at pins
2-5 and 2-6. The voltage at these pins is dependant
on charging system voltage as shown in the table

belovi-.

'in 2-5
2.3V
2.4 V
2.5V
2.7V
2.8V
3.0V
3.1V
3.2V
3.4V
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
3.2V
3.4V
3.5V
3.7V
3.8V
4.0V
4.1V
4.3V
Charge Volts
9.0V
9.5V
lO.OV
10.5V
11.OV
11.5V
12.0V
12.5V
13.0V
13.5V
14.0V
14.5V
15.0V
15.5V
16.0V
If the diagnostic monitor measures a voltage of 2.0
volts or less on pins 2-5 and 2-6, a fau It code 13 will
be generated and flashed to the instrument pack to
be signalled on the airbag warning lamp. Voltages
as low as 2.0 volts indicate a possible short to
ground in these circuits.
When generating a code 13 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 repairing the short circuit, if the
voltage at pins 2-5 and 2-6 returns to normal, fault
code 51 (blown thermal fuse) will be stored in
memory.
6.
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 airbag diagnostic module. Switch
on the ignition.
Measure the continuity to ground at the following
pins on the diagnostic module harness connector:
2-2 Passenger airbag feed
2-3 Passenger airbag return
2-4 Drivers airbag return
2-5 Drivers airbag feed
2-11 Safing sensor feed
If no short circuit is detected, go to step 4.
If
a
short circuit is detected, disconnect the relevant
airbag simulator or the safing sensor and repeat the
continuity measurement to isolate the circuit fault.
Service the wiring or replace the safing sensor as
necessary. Fit a new airbag diagnostic module and
rearm the airbags (6.4.21.4).
Check for intermittent short circuits in the cable
reel cassette. Monitor the continuity to ground at
pins 2-4 and 2-5 whilst rotating the steering from
lock to lock in both directions.
If no short circuit is detected, go to step 5.
If a short circuit is detected, replace the column
switchgear assembly. Fit a new airbag diagnostic
module and rearm the airbags (6.4.21.4).
WARNING: Do not attempt to make any electrical
measurements on the airbag
modules.
Any induced
voltage can
cause
the airbag
to
deploy with the
risk

of personal
injury.

Fit a replacement diagnostic module and
replacement airbag modules.
Caution: Do not refit
the
old
airbag
modules.
They may

be faulty and would
damage the
new diagnostic module.
Rearm the airbag system (6.4.21.4).
6-86 September 1996

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

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

Electrics
Airbag System =2?
Airbag DM Fault Code 24
Safing sensor output - battery feed/return open
circuit.
Normal Operation
The diagnostic module measures the voltage on
diagnostic module pins 2-5 and 2-6 the voltage
varies with the vehicle charge level
as
shown in the
table below:
in 2-5
2.3V
2.4 V
2.5V
2.7V
2.8V
3.0V
3.1V
3.2V
3.4V
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
3.2V
3.4V
3.5V
3.7V
3.8V
4.0V
4.1V
4.3V
Cliarge 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
The diagnostic module also measures the voltage at
pin 1-7 (battery input). Using the battery input
voltage, the system can predict the expected voltage
level on pins 2-5 and 2-6. If the voltage on pins 2-
5 or 2-6 is higher or lower than expected, a fault
code 24 will be declared.
Possible Causes
• Open circuit or high resistance in the wiring
harness or safing sensor.
• Intermittent battery voltage on pin 1-7
• The resistance of the pin 2-5 to 2-6 circuit to

ground.
This circuit should be open to ground at
all times.
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.
Probe the battery input voltage terminal
1
-7. Start
the engine and monitor the charge voltage level
using a digital multimeter. Run the engine at idle
speed and look for any instability in the voltage

level.
Run the engine at a constant medium speed
and then at a constant high speed and repeat the
observation for voltage instability.
If the voltage levels are stable, go to step 3.
If instability of the voltage level is observed,
Investigate and rectify the problem in the charging
circuit.
3. Switch off the ignition. Disconnect the diagnostic
module and check for OQ continuity from pins 2-5
to 2-6.
If no resistance is detected, go to step 4.
If any resistance is detected between pins 2-5 and

2-6,
service the wiring or safing sensor to achieve
Ofi continuity.

4.
Measure the resistance to ground from pins 2-5 and

2-6.

If no short circuit is detected, replace the diagnostic
monitor. Rearm the airbags (6.4.21.4).
If
a
short to grou
nd
is detected, service the wiring or
safing sensor as necessary. Rearm the airbags
(6.4.21.4).
6-90 September 1996

Electrics
Airbag System ^^?
Airbag DM Fault Code 35
Passengers airbag circuit low resistance or short
circuit.
Normal Operation
The diagnostic module measures the resistance
across pins 2-2 and 2-3 every time the ignition is
switched on. The resistance should be 0.9 to
1.1Q..

If the total resistance in the passengers airbag
circuit falls below 0.7S2, fault code 35 will be
declared and the airbag lamp will be illuminated.
f^ote:
The
nominal
resistance
of the airbag simulator
is

2.5£2,
therefore expect
a
total circuit
resistance
reading of
2.4 - 2.6Q with the simulator fitted.
Caution: The passengers airbag connector contains
shorting bars which short circuit pins 1 and 3 of
both sides of the connector when disconnected.
DO NOT REMOVE OR DISABLE THE AIRBAG
CONNECTOR SHORTING BAR UNDER ANY
CIRCUMSTANCES.
The airbag harness shorting bar may be temporarily
disabled during the following resistance checks.
Possible Causes
• Poorly mated airbag harness connector. If the
connector is poorly mated, the shorting bars
may not be fully retracted.
• Faulty shorting bar may short circuit 2-2 and 2-
3 together.
• A short across the airbag terminals in the
passengers airbag module.
Fault Analysis

1.
Disarm the airbag system and check the security of
the passengers airbag module connector before
disconnecting.
If the connector is secure, complete the disarming
procedure, fit the airbag simulators (6.4.21.4). Go
to step 2
If the connector is insecure, service as necessary,
clear the code 35, rearm the airbags. Check that
code 35 does not recur.

2.
Disconnectthediagnostic module and removethe
plastic wedge from connector 2 (black). Measure
the resistance between pins 2-2 and 2-3. The
resistance should be 2.4 - 2.6Q.
If the resistance is 2.4 - 2.6Q, go to step 4.
If the resistance is below 2.4 - 2.6fl, go to step 3.
3. Disconnect the airbag simulator at the passengers
airbag module and remove the plastic wedge from
the harness connector. Measure the resistance
between pins 2-2 and 2-3 at the diagnostic module
connector.
If the resistance is infinity, the airbag harness is
good at this time. Swap the airbag simulators at the
drivers and passengers airbag connectors. Repeat
the resistance check. If the resistance is less than
infinity, there is a fault in the passengers airbag
harness connector. Service the connector or replace
the harness as necessary. Refit the plastic wedges.
Reconnect the diagnostic module. Clear the code

35.
Rearm the airbags.
If the resistance is less than infinity, service the
bulkhead harness as necessary. Refit the plastic
wedges. Reconnect the diagnostic module. Clear
the code 35. Rearm the airbags (6.4.21.4).

4.
Since the circuit resistance is in specification, the
fault must lie in the diagnostic module or in the
airbag module.
Substitute a known good diagnostic module. If
code 35 recurs with the airbag simulator fitted,
there is still a fault in the wiring or the simulator.
If the fault code 35 does not recur, rearm the airbags
(6.4.21.4) and retest.
If fault code 35 recurs with the airbag module fitted,
the airbag module is faulty. Replace the passengers
airbag module (7.8.02.6).
6-94 September 1996

Electrics
Airbag System
Airbag DM Fault Code 41
Right hand crash sensor feed or return open circuit.
Airbag DM Fault Code 42
Left hand crash sensor feed or return open circuit.
Normal Operation
The diagnostic module constantly measures the
voltage at pins
1
-2 and
1-11.
The voltage should be
10±1 volt. The two wires are connected together
within the right hand crash sensor. If the voltage at
1-2 falls below that at 1-11, an open circuit has

occurred.
Fault code 41 will be declared and the
airbag lamp will be illuminated.
Normal Operation
The diagnostic module constantly measures the
voltage at pins
1
-6 and
1
-12.
The voltage should be
10±1 volt. The two wires are connected together
within the left hand crash sensor. If the voltage at
1
-
5 falls below that at 1-12, an open circuit has

occurred.
Fault code 42 will be declared and the
airbag lamp will be illuminated.
Possible Causes
• Open circuit in the wires from diagnostic module
pins
1
-2 or
1 -11
to the right hand crash sensor.
• An open circuit within the right hand crash
sensor across pins 1 and 2 of the sensor
connector.
Fault Analysis

1.
Disarm the airbag system and fit airbag simulators
(6.4.21.4).

2.
Disconnect the diagnostic module and check
continuity between pins 1-2 and 1-11.
If the resistance is significantly greater than OQ, go
to step 3.
If the circu it resistance
is
OQ.,
the
fau It
is intermittent.
Manipulate the harness, particularly in the area of
the sensor connector and the crash sensor harness
to bulkhead harness connector, to identify the
location of the open circuit. Service the circuit as
necessary.
3. Check the right hand crash sensor connector for
security and service the connector if necessary.
If the connector is secure, disconnect and check
continuity from pin 1 to pin 2 of the sensor.
If the resistance is
h igh
or
an
open circuit
is
detected,
replace the crash sensor.
If the sensor continuity is good (0^2), service the
crash sensor loom or bu Ikhead harness
as
necessary
to remove the high resistance or open circuit.

4.
With the airbag simulators in circuit and all
connectors in place, clear the code
41.
Switch off
and then on again to check that the airbag warning
lamp comes on at 'ignition on' and extinguishes
after approximately six seconds.
5. Switch off and rearm the airbags (6.4.21.4)
3.
Possible Causes
• Opencircuitinthewiresfromdiagnosticmodule
pins
1
-6 or
1
-12 to the left hand crash sensor.
• An open circuit within the left hand crash sensor
across pins 1 and 2 of the sensor connector.
Fault Analysis
Disarm the airbag system and fit airbag simulators
(6.4.21.4).
Disconnect the diagnostic module and check
continuity between pins 1-6 and 1-12.
If the resistance is significantly greater than OQ, go
to step 3.
If the circu it resistance
isO£2,
the fault is intermittent.
Manipulate the harness, particularly in the area of
the sensor connector and the crash sensor harness
to bulkhead harness connector, to identify the
location of the open circuit. Service the circuit as
necessary.
Check the left hand crash sensor connector for
security and service the connector if necessary.
If the connector is secure, disconnect and check
continuity from pin 1 to pin 2 of the sensor.
If the resistance is high or
an
open circuit is
detected,

replace the crash sensor.
If the sensor continuity is good (OQ), service the
crash sensor harness or bulkhead harness as
necessary to remove the high resistance or open
circuit.
With the airbag simulators in circuit and all
connectors in place, clear the code 42. Switch off
and then on again to check that the airbag warning
lamp comes on at 'ignition on' and extinguishes
after approximately six seconds.
Switch off and rearm the airbags (6.4.21.4).
September 1996 6-95

Electrics
Airbag System o
--i.
D^?
Airbag DM Fault Code 44
Right hand crash sensor incorrectly mounted.
Normal Operation
The diagnostic module constantly measures the
resistance between pins 2-8 (RH crash sensor
ground) and
1
-3 (airbag DM system ground). If the
resistance rises above 2Q, fault code 44 is declared
and the airbag warning lamp is illuminated.
Possible Causes
• Loose sensor mounting or an accumulation of
dirt or corrosion at the sensor mountings.
• An open circuit or loose wire from DM pin 2-8
to the sensor.
• An open circuit wire or loose rivet within the
sensor.
Fault Analysis
Disarm the airbag system and fit airbag simulators
(6.4.21.4).
Disconnect the diagnostic module and check
continuity between pins 1-3 and 2-8.
If the resistance is significantly greater than
OQ,,
go
to step 3.
Ifthe circuit resistance
is
OQ,thefault is intermittent.
Manipulate the harness, particularly in the area of
the sensor connector and the crash sensor harness
to bulkhead harness connector, to identify the
location of the open circuit. Service the circuit as
necessary.
Check the right hand crash sensor mounting for
security and corrosion.
If neither problem is evident, go to step 4.
If either problem is evident, remove, clean and
resecure the sensor. Reconnect the diagnostic
module. Switch on and clear the code 44. Switch
off and then on again to check that the airbag
warning lamp comes on at 'ignition on' and
extinguishes after approximately six seconds.

4.
Check the right hand crash sensor connector for
security and service the connector if necessary.
If the connector is secure, disconnect and check
continuity from pin 1 to pin 2 of the sensor.
Ifthe resistance is high or
an
open circuit isdetected,
replace the crash sensor. Go to step 5
If the sensor continuity is good (OQ), service the
crash sensor harness or bulkhead harness as
necessary to remove the high resistance or open
circuit. Go to step 5.
5. With the airbag simulators in circuit and all
connectors in place, clear the code 44. Switch off
and then on again to check that the airbag warning
lamp comes on at 'ignition on' and extinguishes
after approximately six seconds.
6. Switch off and rearm the airbags (6.4.21.4)
6-96 September 1996

"3^=2?
Electrics
Airbag System
Airbag DM Fault Code 45
Left hand crash sensor incorrectly mounted.
Normal Operation
The diagnostic module constantly measures the
resistance between pins2-9 (LH crash sensor ground)
and
1
-3 (airbag DM system ground). If the resistance
rises above 2£2, fault code 45 is declared and the
airbag warning lamp is illuminated.
Possible Causes
• Loose sensor mounting or an accumulation of
dirt or corrosion at the sensor mountings.
• An open circuit or loose wire from DM pin 2-9
to the sensor.
• An open circuit wire or loose rivet within the
sensor.
Fault Analysis

1.
Disarm the airbag system and fit airbag simulators
(6.4.21.4).

2.
Disconnect the diagnostic module and check
continuity between pins 1-3 and 2-9.
If the resistance is significantly greater than OQ, go
to step 3.
If thecircuit resistance
is
OQ,
the fault is intermittent.
Manipulate the harness, particularly in the area of
the sensor connector and the crash sensor harness
to bulkhead harness connector, to identify the
location of the open circuit. Service the circuit as
necessary.
3. Check the left hand crash sensor mounting for
security and corrosion.
If neither problem is evident, go to step 4.
If either problem is evident, remove, clean and
resecure the sensor. Reconnect the diagnostic
module. Switch on and clear the code 45. Switch
off and then on again to check that the airbag
warning lamp comes on at 'ignition on' and
extinguishes after approximately six seconds.

4.
Check the left hand crash sensor connector for
security and service the connector if necessary.
If the connector is secure, disconnect and check
continuity from pin 1 to pin 2 of the sensor.
If the resistance is high or
an
open circuit isdetected,
replace the crash sensor. Go to step 5
If the sensor continuity is good (OQ), service the
crash sensor harness or bulkhead harness as
necessary to remove the high resistance or open
circuit. Goto step 5.
5. With the airbag simulators in circuit and all
connectors in place, clear the code 45. Switch off
and then on again to check that the airbag warning
lamp comes on at 'ignition on' and extinguishes
after approximately six seconds.
6. Switch off and rearm the airbags (6.4.21.4)
September 1996 6-97