[. . . ] The operator may then remove the ignition key without shutting the engine down. [. . . ] Movement of the vehicle is prohibited by interlocking the SAFETY LOCK 4 with the brake light switch, a neutral safety switch on the gearshift or a parking brake operated switch. Operating any one of these will cause the relays in the SAFETY LOCK 4 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. Mount unit in a suitable location protected from moisture and excessive heat. 2. The relay will close, the LED will be illuminated and the engine will continue to run when the key is removed. The LED will continue to be illuminated and the engine will continue to run. [. . . ] The LED will continue to be illuminated and the engine will continue to run. [. . . ]