I bought a 2006 GMC Sierra 1500 5.3 a couple of years back and have been fixing issues ever since. Recently I was going for a trip and my radio starts to cut on and off. Then my alternator gauge drops to zero, but everything still works as it should. I restarted my truck, and everything went back to normal for another 30 mins or so, then all gauges dropped to zero, radio shuts off, everything besides my speedometer. I also noticed my doors will keep locking in intervals of 5 times I believe. I have checked fuses, bought a new battery, and upgraded my alternator to no avail. I have looked on other subforums and found people with the exact same issue but no answers to the problem.