Transmission speed sensors are used to calculate the precise gear ratio of the transmission whereas in use. There are usually two speed sensors that work in conjunction to offer correct transmission knowledge to the vehicle’s powertrain management module. The primary is called the enter shaft speed (ISS) sensor. As described, this sensor is used to watch the speed of the transmission’ enter shaft. The opposite sensor is the output shaft speed (OSS) sensor. If both of these two sensors falls out of alignment or expertise electrical points, it impacts the operation of the complete transmission.
After registering knowledge, the two transmission speed sensors, additionally generally known as vehicle speed sensors (VSS), ship knowledge to the powertrain management module (PCM), which compares these two inputs and calculates which gear the transmission ought to interact for environment friendly driving. The precise gear ratio is then in comparison with the desired gear ratio. If the desired gear and the precise gear don’t match, then the PCM will set a diagnostic hassle code (DTC) and illuminate the Examine Engine Mild.
Ought to both or each of these speed sensors fail, chances are you’ll discover one or extra of the following points:
1. Harsh or improper shifting
With out a legitimate speed sign from these sensors, the PCM will be unable to appropriately management the shifting of gears inside the transmission. This may increasingly trigger the transmission to shift roughly or extra shortly than regular. It is also widespread that a drawback with these sensors can influence the shift timing, extending the interval between transmission shifts. An automated transmission is hydraulically managed and designed to shift easily. When the transmission shifts onerous, it may possibly injury inner elements together with valve our bodies, hydraulic strains, and in some instances mechanical gears. For those who discover that your transmission is shifting harshly or roughly, it is best to contact a mechanic as quickly as attainable.
2. Cruise management doesn’t work
Since the transmission speed sensors monitor the enter and output shaft speed, it additionally performs a half in monitoring the cruise management. When the sensors fail to ship correct knowledge to the onboard pc in your car, truck, or SUV, the powertrain management module (PCM) will ship an error code to the vehicle’s ECU. As a safety precaution, the ECU will shut down the cruise management and render it inactive. For those who discover that your cruise management doesn’t interact whenever you press the button, contact a mechanic to allow them to examine the vehicle and decide why the cruise management shouldn’t be working. It might be as a result of defective transmission speed sensors.
three. Examine Engine Mild comes on
If the alerts are misplaced from the transmission speed sensors, the PCM will set a DTC and illuminate the Verify Engine Mild on the vehicle dashboard. It can also point out that there’s a rise in tailpipe emissions that surpasses acceptable limits for environmental contaminants from motor automobiles.
In any case, when you discover that the Verify Engine Mild comes on, it is best to contact a mechanic to scan the error codes and decide why the Verify Engine Mild is illuminated. As soon as the drawback has been fastened, the mechanic will reset the error codes.
If the drawback rests with the speed sensors, relying in your specific transmission, a mechanic could possibly exchange the sensor. Some speed sensors are inner to the transmission and would require the transmission to be faraway from the vehicle earlier than the sensors could be changed.