Anti theft blinking

You will need to retrieve the trouble codes to see what direction to take with diagnosis. These truck have a tendency to lose key programming after a dead battery event, and the occasional and semi-rare PCM (powertrain control module) failure. But as I stated, retrieve codes first because it just might need a reprogram. If you only have 1 key, don’t do the “erase all key codes” option if you reprogram because 2 keycodes need to be programmed in the system to deem the anti-theft system functional.