Front impact sensor

WARNING: This page is about a different car, the 2005 Saab 9-3. However, it is still accessible from the selected car via links, so may be relevant.

The front impact sensors detect possible impact intensity at an early stage and send information to the control module. The front impact sensors send digital information containing the status message for diagnosis and the acceleration value in 120 levels to the control module via the lead. The control module performs a calculation and decides whether to activate the detonators. If the front impact sensors are not functioning, the airbags are still activated but with a slightly later detonation. See CONTROL MODULE information. The front impact sensors are grey in colour.

Fig 1: Identifying Front Impact Sensor

Courtesy of SAAB-SCANIA OF AMERICA, INC.

The front impact sensors communicate by modulating the continuous voltage feed from the airbag control module which means that the sensors use more or less current. Changes are registered by a microprocessor in the control module.

Identification message - during start-up
Status message for diagnostics every 220 ms (as an information packet).