PURPOSE: To reduce the number of terminals of a control unit for the number of signals required by providing a discriminating means by which which signal generating means is operating is judged.

CONSTITUTION: Respective signal generating means generate signals in accordance with their respective setting conditions, and based on these signals, a control unit 2 changes the exciting solenoid in an electronic hydraulic control circuit to control a transmission 1. And out of these signal generating means, a plurality of signal generating means 5, 6 to be connected to a common input terminal 7 of the control unit 2 generate respective signals in different regions each having a different condition each other. These signals are input into the control unit 2 through a common terminal 7, and it is judged from the difference in respective signal generating conditions that from which signal generating means the signal has been generated.