Hub Assembly 2001 Olds Bravada

I have the "brake" and "abs" light come on. I replaced brakes on all four thinking this would fix the problem. I replaced front-wheel hub assemblies which fixed the lights from coming on. But know they come on intermittently. Do the rear hub assemblies have electrical sensors as do the front? I don't hear any sort of grinding/groaning sounds from the rear. Tired of looking like a Christmas tree on my dash.