Automatic transmission speed sensor for Mercedes
An automatic transmission speed sensor is a device that measures the rotation speed of the input and output shafts of an automatic transmission (automatic transmission). This signal is used by the electronic transmission control unit (AT ECU) to determine the optimal gear shift point and to ensure smooth and efficient shifting.
Location
The automatic transmission speed sensor is usually located on the automatic transmission housing, next to the input or output shaft.
Design
The automatic transmission speed sensor consists of the following main components:
* Magnetic sensor: Converts mechanical shaft rotation into electrical impulses.
* Tooth Ring: Mounted on a shaft and has a specific number of teeth that pass through a magnetic sensor.
* Electrical wires: Transmit impulses to the automatic transmission ECU.
Operating principle
As the shaft rotates, the teeth on the toothed ring pass the magnetic sensor. Each passing tooth causes a change in the magnetic field, which in turn generates an electrical impulse in the sensor. The number of pulses per unit time corresponds to the shaft rotation frequency.
Automatic transmission ECU
The automatic transmission ECU analyzes signals from the automatic transmission speed sensor to determine the rotation speed of the input and output shafts. This information is used for:
* Determining the optimal gear shift moment
*Hydraulic pressure control for smooth and efficient gear shifting
* Detecting slippage and preventing damage to the automatic transmission
Malfunctions
Malfunctions of the automatic transmission speed sensor can lead to the following problems:
* Incorrect gear shift points
*Hard or slipping shifts
* Automatic transmission fault codes
* Automatic transmission emergency mode
Diagnostics and replacement
Diagnosis of automatic transmission speed sensor faults is usually performed using a diagnostic code scanner or a multimeter. To replace the sensor, you need to drain the transmission fluid, disconnect the electrical connector of the sensor and unscrew the sensor from the automatic transmission housing.