Make shift kill switch?

Soon after I arrived at NAS Miramar, spring of 70, I made friends with a guy who I remained friends until his death. At the time he was young and going to engineering classes. Brand new K20 Chev 2500. Ignition switch IN THE DASH. He put together a little circuit that required a particular letter be sent --in Morse- via the brake pedal, I think "C" (Dah di dah dit) If you did not do that it would not start. I don't know if it worked, but the truck never got stolen!!

He lived in Paradise Hills, near National City. It was not quite as ghetto then as it is now