Not sure if this means anything but the ABS and TCS warning lights are not consistently on now as of yesterday's drive home after the car sat all day. They come on for like a minute then go out for 10-15 minutes then come on again and it repeats.

Clearly some kind of sensor is fouled up here? Also no leaks spotted on the ground when I pulled out of my parking spot.

I just had this problem on one of my trucks. Turns out it was a bad sensor. But, since replacement parts are all made in China (yes, even genuine GM parts), sometimes they are slightly out of spec. That’s why the replacement sensor wouldn’t work until we changed the hub assembly- even though the hub assembly was recently replaced.

On my GMC, if a wheel assembly is not communicating with the computer, it will work as old school brakes, the other wheels will still have the ANS action though. I drove with my mystery ABS failure for a year until I could get time to get it sorted out. The truck stopped normally the whole time. And yes I put black tape over the warning light because I didn’t want to keep looking at it.