Gauges go to zero, battery light on and radio won't come on.

[Youngblood25]

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.

Edited March 14, 2022 by Youngblood25

[EightTrackHits]

You’ve started with everything that I would start with.  Check grounds of course.  Check continuity of the harness from the alternator if you have a schematic and a multimeter.

 I think this issue is a good candidate for a dealer scan.  
Please follow up and let us know what you find out.

[richard wysong]

how many keys on your key ring? too many may be turning the switch just enough to shut it partially off or you may have a bad ignition switch

[dna9656]

Listen to Richard, he's pretty sharp. I had all kinds of weird S _ _ _ going on with my gauges, I got a overhaul kit for the stepper motors (the are what moves the needles on your gauges) and replaced them all to no avail, so I sent off on the web for a overhauled one and have had no problems like that since. These trucks have electrical systems akin to to the ones on old British motorcycles. A company called Lucian made harnesses for BSA, Triumph, others that was nothing but trouble; they were known as Lucian Prince of Darkness Electrical Systems. They were not just poorly made they were poorly designed.

[Cade Sartin]

im having the same problem  checked all the grounds ik of and still not working