How to?

Problem is, abs and track control warning light on sometimes. When are restart the car I can drive a whole day without any warning.

Before I change my break pads rear and front the were very used. Some rust all around my wheel so I guess have rust dust inside also

I been to GM, but my warning light was off, when they scan it no code detected.

When the light turn on again, I press onstar for a diagnose, no code also even if the warning light is open!

What can be the problem?