I've got a 2014 Silverado High Country with every option (even the old man color-matched mud flaps with the bowtie engraved), crew cab longer bed, with the 5.3L and a fresh 6l80e rebuild. It's right at 144,000 miles now.
I run a Range AFM tuner and I have called before to ask what associated codes I should expect with the tuner, knowing it will aggravate the computer by using OBD port continuously, up to a certain level. I was assured it wouldn't upset the system or throw any codes. I'll call again today to make sure everything is updated and working properly on the Range side of things.
What I have done:
G218 ground clean up
G141 ground clean up
No codes found whatsoever.
Battery, alternator, and voltage regulator checked ok. zero other electrical gremlins other than those listed below:
What is still going on, about a month now:
Upon startup, I'll get service Stabilitrak, Brake Assist, Trailer Brake System, and a new one, when I come to a stop, the [service] Park Assist System will pop up.
Other odd symptoms - I remote start the truck regularly, and about 25% of the time, it simply won't turn on. It'll respond to my key inputs, but won't turn on, just as it should when a CEL is on or the fuel level is low.
Additionally, I remote started the truck at Autozone this morning. Started fine. I unlocked it, pulled the hood release latch, and the truck shut off. Same thing happened when I repeated the sequence. No other odd light or electrical anomalies other than the truck shutting off as if it was instructed to.
The only connection I can make would be the location of them all, which I will dig into today. The Stabilitrak and Park Assist systems both have buttons below the infotainment system, and I had the dash apart just a couple months ago to swap out pieces for the Apple Carplay/Android Auto upgrade. I'll tackle that today, in addition to rechecking all fuses, but I've been on top of those for the most part.
Another important note is that I've had issues with the trailer light signals coming out of the back of the truck for the better part of a year now, so the Trailer Brake System/Trailer Lights disconnected messages are not new and could be associated to my redneck fixes. I'd have poor connections or no connections with my boat trailer and no issues with the trailer wiring or grounding itself, and after a fit of rage, I added another ground off of the 7/4 pin stamped into the bumper and routed it directly to the frame at the rear of the truck, cleaned up the ground and all. I have also soldered each of the 7 wires to the 7 pin connector directly after confirming the connector works on another truck. Certainly not GM approved, but it's working fine, and has for the last year. I do understand the system is sensitive and most likely the reason I get those associated trailer messages, but if it could lead to the other messages, that's important.
I appreciate any leads to tracking this gremlin down. I've got a Haynes manual and the wire chasing has been unsuccessful, in addition to the lurking on this site and completing random improvements.