Control system with failsafe for shift-by-wire automatic transmission

A control system for a shift-by-wire automatic transmission, comprising:

• a first range changing valve for having a first range changing valve input port switched to communicate with a first range changing valve first output port and a first range changing valve second output port;
• a second range changing valve for causing a second range changing valve first input port connected with said first range changing valve first output port to communicate with first and second range ports selectively and for causing a second range changing valve second input port connected with said first range changing valve second output port to communicate with at least a third range port selectively;
• and drive means for switching and operating said first and second range changing valves;
• failure determining means for determining a failure that one of said first range changing valve and said second range changing valve fails to be switched;
• and
• failure control means for outputting an instruction signal to said drive means to change the range by actuating the other of said first range changing valve and said second range changing valve if said failure determining means detects said failure.