Impact Sensor: Description and Operation

NOTE: The Impact Senor and the Safing Sensor are in the control module, and can not be serviced separately.


Two sensors are contained within the ACM, an electronic impact sensor and a safing sensor. The electronic impact sensor is an accelerometer that senses the rate of vehicle deceleration, which provides verification of the direction and severity of an impact.
A pre-programmed decision algorithm in the ACM microprocessor determines when the deceleration rate as signaled by the impact sensor indicates an impact that is severe enough to require airbag system protection. When the programmed conditions are met, the ACM sends an electrical signal to deploy the airbags.

The safing sensor is an electromechanical sensor within the ACM that is connected in series between the ACM microprocessor airbag deployment circuit and the airbags.
The safing sensor is a normally open switch that is used to verify or confirm the need for an airbag deployment by detecting impact energy of a lesser magnitude than that of the electronic impact sensor, and must be closed in order for the airbags to deploy.

The impact sensor and safing sensor are calibrated for the specific vehicle, and are only serviced as a unit with the ACM.