What is the Impact Sensor?

The impact sensor is the device that sends the signal to the airbag module to then send another signal to deploy the airbags.

The airbag module does detect which impact sensor the signal is coming from, so this way it knows which airbags to deploy through the location of the sensor. The module also knows which seats in the car are being used, so it knows whether or not the passenger airbag needs to be deployed.

What are the different types of impact sensors?

There are two main types of collision sensors, the Mass-Type sensor, and the Roll-Type sensor.

  • Mass-Type sensor  – this works off of the inertia of the mass is the center of the sensor. When a collision happens at a high enough intensity, the mass will push forward into a plate that is holding two contacts. When the plate is hit hard enough, the two contacts will be pushed flat so that they touch each other as well as the terminals.
  • Roll-Type sensor – This sensor also works off of inertia, however, with this sensor the contact will roll and unravel itself towards the other terminal. If the crash intensity is not hard enough then the contact will roll back without making contact with the second terminal. If the crash intensity is hard enough then the contact will roll forward all the way closing the connection which sends the signal for the airbags to be deployed.

Where is the impact sensor located?

In most cars, the impact sensor is located somewhere within the engine bay, as well as some smaller sensors around the car for more regional detection.