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Transmission Speed Sensor: Description and Operation

Output Shaft Speed Sensor


Output Shaft Speed (OSS) Sensor:






The Output Shaft Speed (OSS) sensor detects the speed of the transmission output shaft. The sensor uses variations in a magnetic field caused by a tone wheel to generate a pulse train output corresponding to shaft speed. The OSS tone wheel uses a repetitive pattern of three different angler displacements between teeth. The pulse width order can be used to determine shaft rotation direction. The magnetic sensor element may be a Hall sensor or a magneto-resistive pick-up. Due to the open collector design and the RC timing involved in the pull-up, the rising edge of the pulse train is not a reliable edge for critical timing, only the falling edge. The pull-up is located in the PCM to provide a wetting current for the sensor connectors. This applies specifically to the TorqShift.