The speed sensor is mounted on the gearcase. It provides the control module with information about output shaft speed via pin 33 (B). The sensor is grounded via pin 23 (B).
The sensor, which is a Hall sensor, measures the output shaft speed from an 18-tooth wheel (parking lock ring gear). The control module uses the frequency of the pulses to calculate the output speed.
The TCM uses the information about the output speed and accelerator position to calculate when gearchanges are to be made. The output speed is also a measure of vehicle speed. The information is used to activate lock-up.
Diagnostics
If output speed is absent, diagnostic trouble code P0722 will be generated and the TCM will go into Limp-Home mode.