A vehicle speed sensor, also known as an engine speed sensor, is a device that measures and transmits information about the speed at which your car’s engine is rotating to the computer system. By measuring the crankshaft’s rotational speed, the sensor detects this. If your speed sensor has been hacked, you may encounter issues within your car.
When the chips are down, the cruise control is not working, the check engine light blinks and requests your attention, and there is harsh or inaccurate shifting. Interestingly, problems with a malfunctioning coil pack or throttle position sensor mimic the symptoms of a damaged transmission speed sensor. For further information, contact a mechanic.
Location Of Speed Sensor
The output shaft of the transmission is frequently in close contact with a transmission speed sensor. The Ford transmission speed sensor is positioned to measure the rotation and speed of the post. The engine computer can then receive this data via the connected wires. The sensors in your automobile are designed to continuously check the speed of the gearbox. Changing the engine’s computer settings may also assist you in reaching your target performance level.
BMW gearboxes include speed sensors for the input and output shafts of the gearbox, which are positioned in the transmission pan. Whereas the output sensor is located closer to the back of the pan, the transmission input sensor is located closer to the front. Two sensors are included in certain transfer cases, whereas others only have one. The rear of the transfer case will include both of them. The transfer case’s tail shaft will house their installation. A physical component with two sensors will have one on the left and one on the right.
The right-hand side is where the speed sensor is located on the gearbox. Check if there is a plug-like part on the side of the device by looking closely. The plug-and-play electrical connection is where the approximately 3-inch-long speed sensor ends.
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Types of Speed Sensors
Wheel speed sensors are divided into two categories: active and passive sensors. The accuracy of active sensors is higher than that of passive ones.
Active Wheel Speed Sensors
The way that active wheel speed sensors function differs significantly from that of their passive counterparts. A wheel speed sensor that is active is only deemed “activated” when it receives a voltage and generates an output signal. The term “activated” can only be used in this context. Active wheel speed sensors are sometimes referred to as magneto-resistive sensors because of their sensing element that is connected to either a magnetic element or a two-pole electric wire.
This occurs as a result of the similarities between the two kinds of sensors. An active sensor works better than a passive sensor because digital signals can detect the direction in which the wheel is turning and are more accurate at low speeds.
Passive Wheel Speed Sensors
Variable-reluctance magnets or inductive sensors are other names for passive speed sensors that are often used. There is no external voltage source required for these sensors to operate. It is located atop the impulse wheel and connected to the drive shaft underneath it.
As a result of variations in the winding from tooth to tooth that result in varying magnetic flows, the sensor detects the speed at which the impulse wheel revolves. The sensor measures the speed due to this variation in the magnets’ flux.
Read: Camshaft Sensor Symptoms and Replacement Process
Four Common Bad Speed Sensor Symptoms
Mentioned below are the four common bad speed sensor symptoms:
1. Transmission Issue:
Shift timing is determined by the transmission control module (TCM) or powertrain control module (PCM) using vehicle speed information supplied by the VSS. The body control module (BCM) can even utilize it for intermittent wiper sweep, which in misty circumstances has to increase in frequency with speed. However, a malfunctioning “door ajar” switch or another issue can affect this. Nonetheless, an automatic transmission’s ability to function will be directly impacted by a malfunctioning speed sensor.
Abnormal automatic gearbox operation is one of the most prevalent indications of a malfunctioning speed sensor. Transmission symptoms including delayed shifts, hard shifts, and restricted gear use may occur if the VSS is malfunctioning.
2. Inadequate Or Harsh Gear Shifting:
When the engine speed sensor or transmission sensor malfunctions, the Powertrain Control Module, or PCM, is unable to regulate how the gears are changed. As a result, you have to transfer gears at faster speeds or risk putting the transmission into late gear. Additionally, your car cannot be put in high gear. It is risky to change your car quickly since it might break internal parts including valve bodies, hydraulic lines, and mechanical gears.
3. The Torque Converter Clutch Is Not Being Used
At a speed predetermined by programming, the torque converter clutch engages. The transmission torque converter, which creates a mechanical link between the engine and gearbox, cannot apply the clutch and create a mechanical link without precise data from the vehicle speed sensors.
This may result in a gearbox overheating, slippage, and decreased fuel efficiency.
4. Engine Speed Sensor Troubleshooting And Repair
Your technician may need to do a thorough computer diagnostic test to determine the nature of the speed sensor issue. The purpose of the car computer was to eliminate the need for the mechanic to manually test various components to diagnose and fix your vehicle. Simply let the auto repair business know about any further bad speed sensor symptoms, and they should be able to rule out any other possible problems with your car. They can then provide you with an estimate for the components and labor costs.
5. The Engine Warning Light
If there is an illuminated “check engine” light on your dashboard, there could be a problem with the speed sensor.
The most reliable method of getting this data is to have a professional do a diagnostic check on your car. Most mechanics will be able to determine whether or not a malfunctioning speed sensor is the reason for your engine light issues.
Finding And Fixing Problems Of Speed Sensors
To prevent potential safety issues and expensive repairs, you must take action right away if you encounter any of the above bad speed sensor symptoms. Electronic diagnostics, visual inspection, and road testing are commonly used in the diagnosis of a faulty speed sensor. To monitor sensor readings and identify the problem’s primary source, a skilled technician will make use of specialized tools.
Once a bad speed sensor has been located, repairing it is quite easy for experienced professionals. However, the specific procedure may vary depending on the model and brand of the vehicle. High-grade replacement parts are required to ensure reliability and longevity.
It’s important to replace the speed sensor in addition to inspecting any associated components, such as wiring harnesses and connections, for damage or corrosion.
The Bottom Line
Several signs indicate bad speed sensor symptoms can reduce an automobile’s reliability, safety, and performance. A broken speed sensor can have serious consequences, such as incorrect speedometer readings, erratic shifting patterns, and ABS issues. To lower risks and restore the vehicle to a functioning condition, prompt diagnostics and repairs are required.
