Any ideas where to start? I've read a mess of stuff on the net but none of it is silverado specific. The brakes work fine.

 

post the codes that have set.

Any bad wheel bearings? The wheel speed sensor is in the hub and bearing assembly. If the bearing has play the wss will be irratic.

 

Ok I'm gonna do my best to help with language that you may understand, I just recently had a problem where my ABS light came on, which I believe they maybe able to find a hard or soft code @ autozone for you. My problem was I took my new 08 chevy to LA Mudfest, not the best idea i don't recommend it. I started to hear this loud grinding noise like gears were just eaing at each other, luckil cause it's hevy it ran over 100k to the autoshop but my rear diffs were destroyed and the balljoints had to be replaced. The BAS cam on because of that reason. Now other things i came across if you did do any offroading or took it through a deep rain puddle the sensor could've been wet and disorientated, especially i it was mud. Other than that man i hope it helps but I know for a fact that light comes on to help prevent any further issue take it in asap cause you wont wanna ut yourself through that labor, Brakes may feel like they slip obviously cause they wont lock anymore. I hope this helps, my opinion take it into someone with more and more experience or the dealer