Output Shaft Speed (OSS) Sensor
The OSS sensor detects the speed of the transmission output shaft. The sensor uses variations in a magnetic field caused by the OSS sensor gear to generate an output signal corresponding to shaft speed. The OSS sensor gear uses a repetitive pattern of 3 different angular displacements between the teeth. The magnetic sensor element may be a Hall effect sensor or magnetic pick-up. Due to the open collector design and the RC timing involved in the pull-up, the rising edge of the OSS sensor gear is not a reliable edge for critical timing, only the falling edge. The pull-up resistor is located in the PCM to provide a current for the sensor. This applies specifically to the automatic transmission.