The Seat Belt Pretensioner System (Where Fitted) - Aston Martin DB7 Workshop Manual

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Electrics
Seat Belt Pretensioner
The Seat Belt Pretensioner System (where fitted)
Description
The DB7 seat belt pretensioner system operates the drivers seat belt pretensioner in conjunction with the Airbag
system. The seat belt pretensioner control module is located under the right hand seat, beside the right hand seat
control module.
The pretensioner control module calculates changes in vehicle speed using an input signal from an accelerometer.
When a collision is detected (Rapid reduction in vehicle speed) and the safing sensor in the airbag system is also
activated, the pretensioner charge is fi red usingelectrical energy stored in a capacitor within the pretensioner control
module. Firing of the pretensioner charge applies additional tension to the drivers seat belt.
The airbag and seat belt pretensioner systems share the SRS (Airbag) warning lamp. Any fault detected by the
pretensioner control module is indicated by constant illumination ofthe SRS (Airbag) warning lamp. Flashing of the
SRS warning lamp indicates a fault in the airbag system.
Should both systems develop faults, the pretensioner system will permanently illuminate the warning lamp. This
would mask the airbag system warning indication. Therefore, rectify the pretensioner fault and then retest for faults
in the airbag system
The pretensioner control module can log up to 10 diagnostic trouble codes together with a time since each fault was
alerted to the driver. Each fau It wi 1 1 be identified as 'Permanent' or 'Intermittent' on the PDU diagnostic trouble codes
screen.
System Connections
DB7 is fitted with an Autoliv ECS or RC5 Pretensioner Control Module. The Pretensioner Control Module has an 18
pin connector featuring six shorting bridges. The mating halves of the connector may be securely locked using a
double mechanical locking system.
The following pins on the control module connector are used in the Aston Martin seat belt pretensioner system:
Pin 1 Ground
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Pin 2 Airbag Warning Lamp
Pin 11 Drivers airbag positive
Pin 12 Drivers airbag negative
Pin 14 Serial communications
Pin 15 12 volt positive feed
Case Ground
15.
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Note: Pins 1 -2, 3 -4, 5 -6, 7 -8,9 - 10 and 11-12 are shorted together by internal shorting links within the connector when
it is disconnected. The short circuits may be temporarily overcome for fault analysis purposes by inserting a suitable non-metallic
cheater (the sBfTiG size 3s the p€gs in the controller connector) into the rectsngul^r hole opposite the relevsnt p3ir of pins.
September 1996
6-101