My son's (my ex) 03 shows PO633 code- "skim key not programmed in PCM". Does that mean you can start the truck with an unprogrammed key? (I was going to try and start it with his unprogrammed key which can just unlock the door, but I thought that might disable it from starting with the programmed key if it is actually still programmed??) I just read the code by the 3 key on- off thing, and I know it can throw false codes.