Speed sensors are widely used in many applications including automotive. Generally, it is being used to acquire positional frequency information from rotating systems. In the case of automotive, the speed sensor is utilized by the anti-lock braking system to know when the wheels are about to lock-up. It is mostly active when the wheels are suddenly skidding. The speed sensor will pick up the impulses and the rotational speed is the information that is going to be sent to the computer. The anti-lock braking system will eventually release more traction which is needed to get less dangerous skidding of the wheels. Your GMC speed sensor is comprised of sensitive parts such as the pickup coil, core, magnet, and rotating ring.
You could also find the speed sensor in the engine system of the automobile. While the speed sensor is used in the anti-lock braking system chiefly to gauge acceleration cornering forces, braking distances, and lap times, in the engine system, its role is to control automatic transmission shift points, fuel delivery and engine timing. If in the ABS system, you'll find this device mounted in each wheel of the vehicle (in some cases, in the differential), you will also see this in the engine system installed in its crankshaft. A speed sensor is comprised of parts such as the pickup coil, core, magnet, and rotating ring.
The roles of each speed sensor may slightly differ in its application but basically it has a general objective: to gather and send the data to the system's respective computer system for the vehicle to perform accurately necessary actions whether to evade dangers or to improve its full operational mode. Both are highly-needed in maintaining the vehicle. If one or both are found to be defective, it could send the wrong signal to the computer management in which could be dangerous enough to result to any kind of mishap. This is why checking and maintaining the speed sensors of your GMC vehicle is highly recommended to prevent any misfortunes. And if need be, replace it with a new GMC speed sensor.