I'm not sure but think miles must be stored in BCM for 04+ GP's, even with having a swapped in 5 button DIC that was at wrong mileage the GM dealer was able to read correct mileage with tech 2 on my buddies 08 GP when they did a reman trans replacement under warranty.when you power up what you'll see what miles?
miles are stored in your dic cluster, not the pcm, or the engine, only the car.