This simple, low cost controller bypasses the ignition switch when activated by the closure of a momentary switch. The operator may then remove the ignition key without shutting the engine down. Movement of the vehicle is prohibited by the foot brake, a neutral safety switch on the gearshift or a parking brake operated switch. Operating any one of these will cause the relay in the SAFETY LOCK to drop out and interrupt the ignition circuit to stop the engine. The authorized operator need only insert the key, and turn on the ignition to operate the vehicle. With the key in the lock and turned on, the ignition circuit is completed as normal and the opening of the SAFETY LOCK relay has no effect on engine operation.