ABS & brake lights come on simulateously, but is intermitant problem. on 2001 Chevrolet Blazer

Not always on when vehicle started, but usually does come on somewhere along the trip. Have noticed that it sometimes comes on if hit pothole or railroad track, like maybe a vibration can trigger it. Is this just a light problem? Or is it a brake issue?

Asked by for the 2001 Chevrolet Blazer
Most likely a wheel speed sensor problem, scan test will confirm but scanner really needs to be connected at the time of the falt! May have to let a mechanic drive it with the scanner hooked up until this happens, that is IF no memory codes can be found.
1 more answer
yes wheel speed sensor is erratic