2016 Yukon Denali Electrical Gremlins

[Jw412]

Was driving on interstate and all gauges went to zero, no power loss. Got to gas station, turned off, and fired it back up and everything was reset. That was 6 months ago. 3 days ago, running up the street from home, all gauges went to zero. Got back home without turning it off and in the garage. When I shut it down and tried restarting, it wouldn’t restart. No crank but full lights. I can hear the relays when I press the button but nothing. Dash lit up like a Christmas Tree. Brand new battery and tested. Interior lights stay on and rear hatch stopped working. Tried working on it for 3 days, got to every ground that I could but not all of the. Was not able to pull A pillar. Pulled under hood fuse panel and removed ground today just checking to see if maybe something was loose or pins bent. Found nothing. When I got it put back together, reattached negative to battery and was able to start it before gremlins came back. Within 30 seconds, gremlins were back but was running so I chose to drive it to shop up the road. Leaving it run at the shop, senior mechanic came out, saw gauges at zero, radio was black, and interior lights on. Also no audible sound from the turn signals, no open door audible chime. He said he saw enough and pressed the button to shut it down. Vehicle would not turn off. He then held the button in for about 30 seconds and it shut down. He is going to dive into it tomorrow but I have no clue what to expect. I am asssuming its something the the body control mod as the rear hatch works off this according to my research. Did I miss something when trying to DIY? Glad I got it started and to the shop to avoid a tow, but upset I couldn’t figure it out on my own. My garage isn’t really set up for me to me climbing around under the vehicle (and its 10 degrees in there ) Hoping I just missed a ground somewhere other than the A Pillar drivers side. I cleaned two on frame behind front wheels and strap on firewall. Also tested negative battery cable using jumper and didn’t help so appeared it is good. Any thoughts? First time poster here.

Thanks all,

John
Pittsburgh, PA

 

[Jw412]

Sorry, maybe should have scanned the other posts more thorough before I posted. I came across one that someone posted about moisture potential in the rear bumper sensors or harness. This could be the issue and I will let the lead mechanic know in the morning to check this. A few months ago, my mirror indicators illuminated and stayed steady for about 45 minutes but it went away, very well could be a moisture issue back there. Especially after getting 18 inches of snow and driving around like a kid in a candy store. Will post follow up once I see what mechanic comes back with.

 

[Joseph Garcia]

Welcome to the Forum from NH.

Lots of knowledgeable folks here who freely share their knowledge, experiences, and perspectives. Knowledge is power.

I hope that you will become a participating member in the Forum's discussions.

Pics of the truck, please.

I'm stumped on this, as well. You did all of the troubleshooting steps that I would have taken. I do believe that it is still related to a ground connection issue, as the symptoms point in that direction, but you appear to have checked all of the critical ground connections.

One question, you said that you cleaned the ground strap connection on the firewall, but did you clean the other end of the ground strap on the motor?

Other members of this Forum much more knowledgeable than me in the K2 series of trucks will chime in.

Keep us posted on progress.

 

[Jw412]

Good evening,

The issue has been resolved. The rear sonar bar or sensor harness had a melted connection. He replaced the harness and it has cleared all codes and no issues with the Christmas tree lights on the dash or no starts. He found it yesterday, replaced the harness this morning and tested it all day. I am heading to pick it up now but he’s confident this was the issue. He mentioned that it was on the driver side rear (I’ll have him show me where when I pick it up) but doesn’t appear that it was against the exhaust. He said more than likely moisture related being in Pittsburgh with the weather we have here.

If anything changes, I will let you guys know. All in repair with troubleshooting, new OEM harness, labor etc was $810 which I feel was respectable considering he’s been at it for 3 days.