mjm-1957

Of course you are correct, brain fade, sorry for the misinformation.

More than likely with that mileage a good decarbonization with top engine cleaner may help to free up the piston rings and may help to lower your oil consumption but it is within GM guidelines.We are told that 1qt per 1000 miles is acceptable as stated above but I agree that is excessive. Just because I work there doesn't mean I agree with that.guideline.

I have been a GM line mechanic for 46 years. When I started in this business we overhauled everything, starters, alternators,steering boxes etc... now everything is throw away crap. Take one out, ****** can it and replace.No skill required.

There is an updated transfer case control module calibration for that exact problem. Call a GM dealer with your VIN and they can run it and check if it was ever done.

There a couple of older bulletins similar to what your describing. I can't figure out how to send a link but the actual bulletins are PIT4730B,document ID #4902455 and the other one is 08-07-30-021H document ID#4213654. They have a lot of good information in them about no start conditions and door locks cycling with gauge cluster problems. Hope you can get access to them. Don't throw anymore parts at this. Its probably a backed out terminal or an intermittent short to ground taking down the high speed lan. Good luck.

Does this vehicle have any aftermarket remote start or alarms added to it? First place I would be looking at if anything was added on. They are usually poorly installed and the components are garbage.

Potential water leak, just like a sun roof.The less openings the better.

Diesel engine takes 15W40 oil not 5-W30.

Give me the last eight of the vin and ill run it to see if you have any warranty left.

Powertrain is 5years -100,000 miles on a 2015. What is your delivery date? Any extended warranty?

You of course slid under there and made sure the shift cable and lever are still in one piece and attached I am assuming?

Does the shift quadrant follow the shifter movements and is there any check engine light on?

I would be looking for a loss of hydraulic pressure like a pump failure or a catastrophic mechanical failure.Any noises while running in gear and not moving?

Even if you unplugged the wiring harness you would still have reverse and one forward gear as a failsafe. That 8 speed transmission is a huge piece of ****** and has been trouble from the start in 2014. I am the transmission guy at a Buick- GMC dealer and can't believe that GM released this trash and can't come up with any fixes for it. I spend most of my time trying to fix the unfixable, harsh downshifts, flares on up shifts, delayed engagement and of course the TCC shudder.Absolute garbage, they should make a retrofit kit to slip a 4L80 in instead.

Me either.