This will be a long story, but I will try to get straight to the point in the hopes this may prove useful to others here.
I purchased my 2019 Silverado RST in July of 2019. It came with a 6" Rough Country lift, 20" wheels and 35" tires installed with 21 miles on the odometer at the time I drove it off the lot. After approximately 3 months (4500 miles) I started getting several malfunctions and warning lights that included;
Service trailer brake system
Steering assist is reduced
Service power steering
Fuel level low
Check Engine Light
Brake Light Illuminated
A/C blowing warm
Gauge needles all acting erratically.
You can see some of these in the following video following this post.
After shutting the truck off and restarting it, all issues remained. I then shut the truck off and disconnected the battery and let it sit for 10 minutes before re-connecting. Upon restarting it, the check engine light remained on, however all the malfunctions went away. I continued my trip home (6 hours). The next morning I decided to take the truck to my local dealership to let them take a look, after less than one mile, all the malfunctions returned. Dealership kept the truck 3 days. They checked all grounds and pinned all wires. Could not locate the issues. So I took my truck home and within two days all issues returned. I left the truck with the dealership again, this time for a week. They ordered a new ECU and gateway and installed both. At the end of the week I took the truck home, didn't even make it all the way home before all malfunctions returned. This time however even trying to shut the truck off was an issue. Pressing the ignition button would kill the engine, but all the electronics would stay active. Pressing the ignition again, and the engine would start, however dash and most electronics would be dark. Disconnecting battery also would not correct the issue. So, I started the engine and drove the truck back to the dealership very carefully.
This time I left it with them for a month (I work offshore) to allow them to get it fixed once and for all. I also had a stern talk with the Manager as well as opened a case with General Motors. I wanted this truck off my hands at this point. Brand new, and already had technicians pull dash out, all wiring harness' apart, and all around just molested the truck (no longer new in my opinion). A GM engineer ended up flying into town to look himself on the 4th week of them having the truck and not being able to figure out what the problem was. It took him literally 4 minutes. He looked under the dash, saw the Hypertech programmer, and unplugged it. They drove it around for a few days and the issues never came back. GM washed their hands of it and cancelled my complaint.
Now, I spent >60k on this truck and still wasn't happy. Now I have a truck that reads approximately 5 MPH off on the speedometer. The truck was opened up and molested several times. However, it looks like there isn't much else to be done at the moment. The funny thing is, GM will not pay the dealership's technicians for all the time spent diagnosing my truck due to it being an aftermarket part that created the problem. However, this dealership installed these aftermarket parts, so they are on the hook, however they don't feel responsible to pay for all the technicians time either. So they pursued the aftermarket company that sold and did the install of the lift, wheels, tires and programmer. Nope...they don't feel responsible. SO on this goes to Hypertech now since the part failed. None of which concerns me. My truck operates like it should now. BUT, I will be taking it to said aftermarket installer to have a new programmer installed soon, and yes, this will also be on the dealerships dime.
So in closing, if you have a lift, have a Hypertech programmer and your dash suddenly goes into chaos mode.....unplug the programmer. I hope this saves someone the time and grief that I went thru.