| 摘要 |
PURPOSE:To ensure travel safety upon occurrence of solenoid stick by constituting such that a down shifted solenoid valve is shifted up when an engine rotation is higher than a setting rotation and maintaining down shift when the engine rotation is lower than the setting rotation. CONSTITUTION:Upon occurrence of solenoid stick in a solenoid valve S1, an automatic transmission having two solenoid valves S1, S2 is brought into power interrupted state and down shifted to 1-speed. Since an engine may be overrun, a computer commands shift down from 4-speed to 2-speed and provides power to the valves S1, S2, then an engine rotation is detected and compared with a setting rotation. If the engine rotation is lower than the set value, power is fed continuously to the valve S2 so as to maintain 1-speed state, while when the engine rotation is higher than the set value and the engine has over run, power is interrupted for the valve S2. Consequently, it is shifted up again to 4-speed thus avoiding overrun of engine. |
