Pressure sensor

Impact sensors are installed in the front and both sides of the vehicle. The use of multiple impact sensors provides shorter air bag trigger times, through faster detection of lateral and longitudinal acceleration, and improves detection accuracy.

There are two front impact sensors, attached to the headlamp surround panel below the headlamps.

There are four side impact/pressure sensors located in the passenger compartment, as follows:

• One attached to the base of each B/C pillar
• One attached to the base of each D pillar.

Each impact sensor incorporates an accelerometer and a microchip powered by a feed from the RCM. The power feed also provides the interface connection through which the side impact sensor communicates with the RCM using serial data messages. Acceleration is evaluated by the microchip and transmitted to the RCM, which then makes the decision on whether or not to activate the air bags and pretensioners.

When the ignition is switched on the RCM supplies power to the impact sensors, which perform a self-test. After satisfactory self tests the impact sensors continually output 'digital acceleration' messages to the RCM. If a fault is detected the relevant impact sensor sends a fault message, instead of the digital acceleration message, to the RCM. The RCM then stores a related fault code and illuminates the air bag warning indicator. Faults can be retrieved by the Jaguar approved diagnostic system from the RCM via the high speed CAN bus connection.