Recently purchased a 1997 C2500 Suburban LT. Has the GM keyless entry system. After a couple of weeks of everything working okay the 'all-unlock' feature of the power door locks quit working. Pressing 'lock' from either front door will lock all the doors but pressing unlock will only unlock that single door. Doesn't matter if you use the keyless entry fob or the actual door switch; neither will unlock all the doors, only the drivers door. When you start the truck with the ignition key, all the doors lock and when you turn it off they all unlock. So, the solenoids work, fuses are good, wiring is good... I bet this is just some crazy programming I accidently activated. Any help out there?