brake problem

[jaybyrd66]

ok guys, got a question for ya, hopefully i can pick at someones brain for a lil bit and come up with some kind of solution here. ive got a 2006 silverado 1500 2wd with 4.3 and auto trans with avalanche 20s on it. heres my problem. it started a couple months ago and has got worse and more frequent here lately when im at speed everything works just fine but when im rolling real slow like thru a parking lot or down my driveway and hit the brakes to stop and at almost every red light and stop sign i come too i hear this kinda grinding noise like my ABS is trying to kick in and then my pedal will drop about an inch and my front brakes just let loose and all i have is rear brakes, i know this cuz i checked in my driveway and when they did it i pressed real hard on the pedal and the back tires just slid and the front didnt do a thing. but i can let up and press the pedal again and everything works fine again. then it will happen again about every time i stop. any ideas at all are appreciated greatly.

[usmcchevy]

Does this sound about right? (borrowed from another post)

Condition
Some customers may comment on ABS activation at low speeds, usually below 8 km/h (5 mph). Upon investigation, the technician will find no DTCs set.

Cause
The cause of this condition may be an increased air gap between the wheel speed sensor and the hub reluctor ring due to rust and debris built up on the sensor mounting surface.

Correction
Measure AC voltage and clean the wheel speed sensor mounting surfaces.

Raise and support the vehicle. Refer to Lifting and Jacking the Vehicle in the General Information sub-section of the Service Manual.
Disconnect both the front wheel speed sensor connectors at the frame and harness.
Place a Digital Volt Meter (DVM) across the terminals of each wheel speed sensor connector.
Rotate the wheel clockwise approximately one revolution per second. The minimum reading should be at least 350 ACmV's. If the reading is less than 350 ACmV's, remove the wheel speed sensor. Refer to the applicable Wheel Speed Sensor Replacement procedure in the ABS sub-section of the Service Manual.
Plug the wheel speed sensor bore in order to prevent debris from falling into the hub during service.
Clean the wheel speed sensor mounting surface using a wire brush, sand paper, emery cloth, scotch brite, or other suitable material. Be sure to thoroughly clean the wheel speed sensor surface. There should be no rust or corrosion.
Check the sensor head to determine if it has been warped/distorted due to the corrosion build up or other causes. Check the mounting surface on the sensor head for flatness by placing it on the edge of a metal machinists scale or other suitable straight edge to measure the flatness. Check the sensor for flatness in multiple (minimum 3) positions/directions. If the sensor head is distorted, replace the sensor.
Apply (spray) two thin coats of the specified rust penetrating lubricant (corrosion inhibitor) to the complete sensor mounting surface on the bearing hub. Allow to dry for 3-5 minutes between coats. Use ONLY Rust Penetrating Lubricant, P/N 89022217 (in Canada, P/N 89022218).
When the corrosion inhibitor is dry to the touch (about 10 minutes), apply a thin layer of bearing grease to the hub surface and sensor O-ring prior to sensor installation. Use ONLY Wheel Bearing Lubricant, P/N 01051344 (in Canada, P/N 993037).
Install either the original sensor or a new one in the hub. Ensure that the sensor is seated flush against the hub. Refer to the applicable Wheel Speed Sensor Replacement procedure in the ABS sub-section of the Service Manual.
Place the DVM across the sensor terminals and recheck the voltage while rotating the wheel. The voltage should now read at least 350 ACmV's.

[jaybyrd66]

thank you very much, that sounds like it might just be the problem. i will check into that as soon as i can. thanks again