Aston Martin DB 9 2010 Manual page 41

Pre-tensioner and Load Limiting Systems
The driver and front passenger seat belts are equipped with
pre-tensioner and load limiting systems.
In most moderate frontal or near frontal accidents, the front airbag
and pre-tensioner systems will deploy simultaneously.
The pre-tensioners take up slack in the seat belts as the airbags are
expanding. The load limiting system releases belt webbing in a
controlled manner to reduce belt force on the occupant's chest.
In some moderate frontal or near frontal accidents, only the
pre-tensioner system will deploy.
Safety Belt Usage Sensors
Safety belt usage sensors detect whether or not the driver and front
passenger safety belts are fastened. The information is used to tailor
the airbag deployment and safety belt pre-tensioner operation
depending upon safety belt usage.
Crash Severity Sensors
Crash severity sensors enhance the ability to detect the severity of an
impact. Positioned up front, they provide valuable information early
in the crash event on the severity of the impact. This allows the
Restraints System to distinguish between different levels of crash
severity and modify the deployment strategy of the dual-stage airbags
and safety belt pre-tensioners.
Restraints Control Module
The Restraints Control Module (RCM) monitors its own internal
circuits and the circuits for the airbag supplemental restraints, crash
sensor(s), safety belt pre-tensioners, safety belt buckle sensors, and
the seat position sensors.
In addition, the RCM also monitors the restraints warning
.
symbol in the instrument cluster
Determining if the System is Operational
The warning symbol in the instrument cluster shows the
condition of the system. A difficulty with the system is shown by
one or more of the following:
• The warning symbol will flash or stay ON
• The warning symbol does not come ON immediately after the
ignition is set to ON
If either of these conditions occur, even intermittently, have the
restraint system serviced at your Aston Martin Dealer immediately.
Unless serviced, the system may not function properly in the event of
a collision.
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