Transaxle Input Speed Sensor

The input speed sensor is mounted in case cover facing drive sprocket. See Figure . Sensor consists of a permanent magnet surrounded by a coil of wire. The sensor mounts into case and maintains a slight air gap (0.045-0.019") between itself and drive sprocket. An AC voltage signal is induced in input sensor by rotating drive sprocket which contains 39 teeth cut in its outside diameter. The voltage output and frequency will vary with housing speed:

• Low Speed = low Hz and voltage amplitude.
• High Speed = high Hz and voltage amplitude.

Inside PCM/TCM, this analog signal is changed to a digital signal. This digital signal is then compared by processor to a fixed clock signal internally within PCM/TCM to determine actual turbine speed. The PCM/TCM uses input speed for control of line pressure and speed calculation. Output voltage will vary with speed from a minimum of 0.5 Volts AC at 100 RPM, to more than 100 Volts AC at 8000 RPM.