Pontiac Repair: Pontiac Aztek brakes, pontiac aztek, speed sensors

Question
Often when I brake, I hear a grinding sound and the pedal vibrates, the brakes do not engage.  If I release the pedal and brake again, they will engage.  My Pontiac dealer has not been able to duplicate these symptoms, but now it is getting worse and my All Wheel Drive Disable light is coming on along with my antilock brake light.  Any ideas about what is wrong?

Answer
Hi Kim:

well if the ABS lamp comes on it will automatically disable the versatrak system on that SUVand it then becomes an FWD only it will not drive the vehicle wit the raer wheels... More then likely you have a ABS wheel speed sensor that is cutting out or a wiring harness issue going to one of the wheel speed sensors. Pretty common issue. If the ABS lamp was on it should have stored a code(s) in that module and it should be pretty easy to at least have a starying point then. If you live in the rust belt like I do wheel spped sensors are VERY common and harness issues runs a close second. Good luck :)