Airbag Dm Fault Code 45 - Aston Martin DB7 Workshop Manual

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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 D M 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 D M 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. G o t o 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