Hello, the only possible way to disable this feature would be if a Chevrolet dealer would agree to do so. They would have to access and reprogram the body control module to turn the feature off. But since it is considered a safety feature, most of them are reluctant to do so. Some basic info below on the system for you. Thanks
The BCM can also control the door lock and unlock relay based on inputs from the power door lock switches, vehicle speed (from the VCM/PCM over class 2 data bus), mini wedge (door jamb switches). The BCM will lock all doors when the vehicle reaches a speed of approx. 15 miles per hour. On vehicles equipped with RKE, the BCM locks or unlocks the doors base on the command received from the remote control door lock receiver on CKT 461 (ORN).
Unfortunately, I don't know what you already know or have tried. But with this system, anything you do to disable the locks so they don't lock automatically will also disable them so they don't lock at all, unless it is done through the computer. That is what controls the automatic sequence. If you unhook the speed sensor, it is going to cause problems with other systems, same if you unhook the computer, same if you unhook the door locks. The only suggestion I can make is that you might try unhooking the light blue wire from the control module at circuit 195 and see it that works. Have never tried it, but do know if it is open the automatics don't work. Other than that a reprogram is the only way I know. Sorry. They don't build those systems so they are easy to defeat. If you try that, do not unhook the wire in a manner that will keep you from reconnecting it just in case. Diagram below. It may not work, but it is the only other thing I can even suggest. Thanks
Schematic and Routing Diagrams | Document ID: 354926