2001 Chevy Silverado External Unlock Btn

I have a 2001 Chevy Silverado Pickup with factory Keyless Entry and security. I have a lot of experience with older keyless entry and alarm systems, but from what I can tell, these newer GM vehicles use some sort of digital interface to control instead of relays. Perhaps someone can give me a brief description of why newer GM vehicles need addon modules to add features. More specifically, I would like to add a hidden external door unlock button (when I lock my keys in my truck). This button doesn't need to unlock startup capabilities just the doors? Do I need some sort of module that connects to OBDII port in order to make this possible? Pardon my ignorance, just trying to wrap my head around the newer technology. Thankswerd

The 2003+ Chevy trucks have the databus controlled door locks. The system goes away from the traditional (+) or (-) activated door systems and uses a data wire to control the locks because this allows less wiring and better communication between the vehicle and the computer system. The 2001 doesn't use this system so you can still use relays to control your locks .Jeff

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