A bad egr leads to reduced power so computer turns off abs and stabilitrak. You are technically in limp mode. Due to bad egr. Every gm car does that.

 

I doubt that it's related, but I had an 07 Equinox that threw those lights on me on a trip from FL to TN. I stopped at an Autozone and asked them to scan the codes and it came up as a bad EGR valve. I thought that was BS, and drove it on home to TN with those lights on. It ran fine. I took it to a buddys shop when I got home and he scanned it and came up with EGR valve too. Hmmmm. I ordered an EGR valve for it, replaced it, cleared the codes and those lights NEVER came back on. I drove it for a few more months, but hated it, so I traded it for a Chrysler 200. The 200 was a much better vehicle. Never mind that, I don't know if that's what's going on with yours, and I have yet to figure out how a defective EGR could effect the abs and stabilitrack, but it sure as hell did on mine.

 

I got a scan tool that does steering angle calibration. It “cleared” stabilitrak light. Till drove it. Then the stabil error message came back. I have a new egr valve. I’ve heard of the egr theory.

 

It's a little soon to tell, but I may have actually fixed the problem or at least found a solution. Catalytic converters.

I had a check engine light (showed up a few months ago, wasn't there from the start of the problem) for my lower 2 O2 sensors. The catalytic converter on the firewall side is right next to the front passenger brake line and the heat shield sort-of vents the heat onto it. I figured it had to be a heat issue because brake fluid expands when its hot, which makes sense why it releases when I crack the bleeders (cracking the bleeders randomly started releasing the brakes, for the first while if you cracked them nothing came out but something changed and I couldn't tell you what)

I replaced both catalytic converters and all 4 O2 sensors (still have the check engine light because I guess I got cheap sensors) and not only does the engine run at operating temperature and never higher (it used to be slightly higher on the highway about half the time) but I haven't had to crack the bleeders in about 3 days, and I've driven about 6-7 hours in that time highway and city. I can still feel in the brake pedal that they start to get a *little* tight, but nowhere near enough to need to crack them.

So the problem isn't completely fixed, but I'm definitely onto something and don't have to crack the bleeders now. My next idea is to flush the entire system and use DOT4 since it's made to handle slightly hotter temps without expanding. I mainly wanted to update this post with at least something since it looks like I completely abandoned it.

Bonus picture of the car in question, will continue to update this thread as the problem changes.

 

Thanks for the update and what you think the problem may be. I'll be interested if your switch to the DOT4 brake fluid makes any difference. Please let us know. After all, we have tried to help you figure it out.