What component sends a message to the airbag module?

The impact sensor is the component responsible for detecting a collision and sending a message to the airbag module. When an accident occurs, the impact sensor measures the force of the impact and determines whether it exceeds a certain threshold that would justify deploying the airbags. If the force is significant enough, the sensor triggers the airbag module, which subsequently activates the airbags to protect the occupants of the vehicle.

Other components, while important to the vehicle's functioning and safety features, do not play a direct role in initiating the airbag deployment. The wheel speed sensor provides information about the speed of the wheels and helps with systems such as anti-lock brakes and traction control but does not communicate with the airbag system in the same way. The brake light switch is used to control the brake lights and may interact with other vehicle systems but does not send messages to the airbag module. Likewise, the steering angle sensor measures the position of the steering wheel to assist with stability control systems but also does not trigger airbag deployment.