What Is an Output Speed Sensor?

by Laura Gittins

In a vehicle, the output speed sensor is also known as the vehicle speed sensor. It sends a signal to the transmission control unit to inform it of the speed of the vehicle.


The output speed sensor measures how fast a vehicle moves and sends that information to other vehicle systems. The transmission control unit uses the speed to determine when to change gears, adjust the torque converter and display the vehicle's speed in the speedometer.


The output speed sensor is a small unit connected to the transfer case. It has a magnetic pickup consisting of a magnet and coil, as well as a rotor with gear teeth. When these spin, it creates a square wave signal. The more signal volts created in the sensor, the faster the vehicle is moving.


Many systems within a vehicle share information from the output speed sensor. The sensor tells the anti-lock brake system when a wheel is locked and tells the power steering system the vehicle's speed so it can determine how much steering pressure to apply.

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