Malinois1

Its the 5.3L with 102,000 miles roughly. The shop went through and cleaned up the fuse box, wiring harnesses etc. Not sure about all the grounds but appreciate the video.

Hello all, thanks in advance for any insight to my starting issue. I have a 2017 GMC Sierra 1500 that is having starting issues in the morning. It's been to the shop several times, and everything checks out good. We're currently thinking it's possibly moisture inside the headlight wiring harness and once it dries out the truck starts just fine. What's happening is when you go turn the key in the morning all the lights come on as normal etc. When you turn the ignition to the start position all the lights go out and when you release the ignition they come back on. Battery, ignition switch etc. have all been replaced. The truck is parked outside at night, when the shop had it, they had it inside and it wouldn't act up at all. When its parked outside over night, I can hook up a battery charger, give it a 100amp boost and the truck will start. When I do this, it does throw a P2535 code and a fuel code but once cleared they don't come back until the next morning when we try and start it. If it's left inside a garage or shop everything works fine. Again, thanks in advance for any assistance.