I just replaced both front wheel hubs with GM OEM parts. Everything went fine, made sure to secure the wires in their clips, made sure no pinched wires, etc. Didn't encounter any issues during this replacement.

The very first time I started the van (before moving it), the Stabilitrak and ABS lights stayed on, displaying their respective "SERVICE" messages on the DIC. I have never seen these lights/warnings aside from normal startup when all the instrument lights come on and shut off.

I drove it around the block, shut it off, drove it again. No noise/grinding/etc. The clunk from the bad bearing is gone at least. I'm not new to working on cars. Everything came out and went back in the same way. Any ideas?

 

there are a plethora of conditions that can trigger the warning.
The easiest way to find out what ... diagnostic scan.

 

I had replaced the upper A arms and encountered the same conditions. Found one of the sensors was seated just a hair off so it wasn't getting a correct reading.

 

Update:

I decided to test the sensors myself before spending money at a shop having diagnostics done. The first sensor I ohm tested was bad. I replaced it with the old sensor and everything is back to normal with the ABS/traction system. I will be getting a warranty replacement and swapping it back out when it arrives.