What Is an Output Speed Sensor?

The output speed sensor is also known as the vehicle speed sensor in a vehicle. It transmits a signal to the transmission control unit, informing it of the vehicle's speed. Failure of the speed sensor is a common reason for taking the car to the mechanic. The speed sensor is a device that detects how fast the vehicle is moving and transmits this information to the vehicle's ECU computer.

This sensor might be found on the output shaft of the gearbox or in the car's crankshaft. For the computer to compare these signals, there will always be two sensors.

Today's Workings of Speed Sensors

The speed sensor signal is received by the PCM and used by multiple systems incorporated into the vehicle through the CAN network, such as stability control systems, ABS braking systems, automatic transmission control and learning, injection management, and ignition time.

What Makes Speed Sensors Work?

Although the numerous speed sensors in your vehicle have distinct functions, they all function in the same way. A reluctor wheel or exciter ring is mounted to whatever rotating equipment is being monitored, and all speed sensors read it. However, the procedure for reading the reluctor varies a lot.

There are three different types of wheel speed sensors.

For example, there are three basic types of wheel speed sensors in use today:

• Variable Reluctance

• Hall Effect

• Magnetoresistive

Variable Reluctance

Because they generate their own voltage, variable reluctance sensors are considered "passive." When the reluctor wheel's teeth pass in front of the sensor, a voltage signal is generated and communicated to the control module.

Hall-Effect

Hall-effect sensors are referred to as "active" sensors since they require an external power source to function. The control module provides a reference voltage to these integrated circuit wheel speed sensors. When the reluctor wheel passes in front of the hall-effect sensor, it excites the integrated circuit inside, which generates the required signal.

Magneto-Resistive 

Magneto-resistive sensors are also referred to as "active" sensors because they have an integrated circuit that allows them to function similarly to hall-effect sensors.

The main difference is that this design can detect both direction and speed.