My 2017 Acadia just started showing the steering assist warning when starting the car. Engine fans keep running on high and a/c stopped. After reading all the threads on this type of problem, a few posts mentioned cleaning the negative battery terminal. I figured worth a try. My terminal was clean, but by removing the battery connector and reattaching it, all the problems went away. Maybe it just reset a sensor? I’ll report back if the problem comes back.