Transmission control system with gear shift failure detection

A method of controlling a transmission control system with gear shift failure detection which includes a transmission, each gear of which is equipped with a synchromesh mechanism;

• an actuator unit consisting of a shift actuator for making a gear shift in a shift direction and a select actuator for making a gear shift in a select direction;
• a control unit for calculating a target position signal from an amount of pressdown of an accelerator pedal, a vehicle speed, and a set position of a gear selector to control not only said actuator unit so that a gear is set within a target range but also a clutch so that connection or disconnection is made according to an operation of said transmission;
• a position detector provided in each of said shift and select actuators for detecting a position of a piston rod;
• a servo cylinder in response to a signal from said position detector to position said piston rod at a given position of each gear;
• a speed detector in response to a signal from said position detector of said shift actuator to detect an operational speed of said piston rod of said shift actuator;
• and a decision maker in response to a signal from said speed detector to decide that a gear shift is faulted if said operation speed is lower than a reference speed for a predetermined time outside a synchromesh mechanism operational range of said transmission, which comprises said steps of:
• turning off said shift actuator so that a hydraulic pressure on said piston rod becomes zero if said decision maker decides that said shift actuator failed to make a gear shift and if the piston rod is at a relatively shallow shift-in position;
• or
• driving said shift actuator into a neutral position if said piston rod is at a relatively deep shift-in position and then making a shift-in operation again.