Many vehicle manual transmission components have a controlling feature that guides the transfer of power from the engine through the drive train and to the wheels. Control modules are the parts that control this transfer of power and are the key components that shift between gears and change the speed of the automobile.
Without a transmission, your vehicle cannot move. The drivetrain connects the front and rear wheels to the engine, and the transmission is the primary power source for motion. If the control module is failing, you may not be able to shift between gears. Other transmission problems might be noticeable by sounds or performance.