What does an output speed sensor do?

The speed sensor, for cars is a part nowadays. Its main job is to detect how fast the vehicle is going and send this data to the cars computer system known as the electronic control unit (ECU). Usually you can find this sensor either on the output shaft of the gearbox or, in the crankshaft of the car.

Importance of the Output Speed Sensor

The output speed sensor is a component, for the operation of different systems in a vehicle. It supplies data to the ECU, which is utilized by systems like stability control, anti-lock braking, automatic transmission control, injection management and ignition timing. If the output speed sensor doesn’t provide information, about the vehicles speed these systems might not function optimally resulting in performance problems and potentially compromising safety.

Types of Speed Sensors

There are several types of speed sensors used in vehicles, including the output speed sensor. The three main types of wheel speed sensors commonly used today are:

  • Variable Reluctance Sensors: These sensors are known as “passive” because they produce their voltage when the teeth of the reluctor wheel move, in front of them. Afterward the voltage signal is sent to the control module.
  • Hall-Effect Sensors: Hall effect sensors are considered as “sensors because they rely on a power source, for their operation. To make these sensors work the control module supplies them with a reference voltage. When the reluctor wheel comes in front of the sensor it stimulates the integrated circuit inside resulting in the generation of the signal.
  • Magnetoresistive Sensors: Like hall effect sensors magnetoresistive sensors are also considered “active” sensors. However they come with an integrated circuit that enables them to detect both the direction and speed of the object being measured.

Each type of sensor has its own advantages and is used in different applications depending on the vehicle’s requirements.

How Output Speed Sensors Work

Regardless of the kind of sensor being utilized the fundamental principle of operation remains consistent. A reluctor wheel or exciter ring is affixed to the rotating equipment that is being monitored. The speed sensor detects this wheel. As the teeth of the reluctor wheel pass in front of the sensor it generates a signal. This signal is then utilized by the control module to determine and gauge the speed of the vehicle.

The control module analyzes the signal acquired from the output speed sensor. It subsequently utilizes this information to calculate and estimate the speed of the output shaft. This valuable data is then employed to regulate and manage systems within a vehicle ensuring functionality and optimal performance.

Common Issues and Troubleshooting

Like any other component, the output speed sensor can experience issues over time. Some common problems associated with the output speed sensor include:

  1. Malfunctioning or Failed Sensor: If the speed sensor that measures how fast the vehicle is moving stops working correctly or has issues it can lead to readings, on the speedometer difficulties with shifting gears, in the transmission or even a complete failure of the transmission. In these situations it becomes crucial to replace the sensor in order to regain functioning.
  2. Wiring or Connector Issues: Intermittent or inaccurate readings, from the output speed sensor can occur due, to wiring or connectors. It is important to examine the wiring and connectors for any indications of damage or corrosion and take measures to repair or replace them.
  3. Contamination or Blockage: The speed sensor that produces the output can sometimes get dirty. Clogged with debris, dirt or bits of metal from the transmission. When this happens it may not be able to provide signals. To avoid problems it is important to maintain and clean the sensor.

If you experience any of these problems, it is recommended to consult a qualified mechanic or technician who can diagnose and resolve the issue effectively.


The speed sensor that outputs data plays a role, in today’s vehicles as it provides information about the vehicles speed to different systems. This information helps the electronic control unit (ECU) manage and optimize the vehicles performance ensuring an seamless driving experience. Having knowledge of how the output speed sensor works and its significance can assist vehicle owners and enthusiasts in maintaining and troubleshooting their vehicles. Upkeep and timely resolution of any issues related to the output speed sensor can greatly contribute to an hassle free time, behind the wheel.

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