I have a 2001 Blazer when the brakes are applied the pedal kicks back then applies normally it doesnt do it when they are slammed on just when approaching a stop sign or something it has 80000 miles and a v-6 and has ABS

 

Take it to a qualified brake service center and have the ABS and Power Brake Booster checked. Something is causing the master cylinder to push back on the pedal...

 

It is quite possible that you have a dirty reluctor ring on one of the wheels that is confusing the ABS speed sensors. If the ABS were to activate, it would tend to push the pedal back at you if you weren't really pressing down hard on it.

There actually is a TSB (technical service bulletin) on this very subject.

 

so what would be the recommendation on what to do or go to a shop and have them look it over. I'm not sure if I'm having the same issue or not. i notice it more when I'm sitting idle the pedal feels like it is pulsing. but isn't really being pushed back at me. Just feels like a vibration in the pedal. mine is a 99 with about 121K miles on it.

 

OK, I've got an '00 Blazer that has this EXACT problem:

Bulletin No.: 02-05-25-006A
Subject: ABS Activation at Low Speeds
Condition: Some customers may comment on ABS activation at low speeds usually below 5mph. 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 builtup on the sensor mounting surface.

Now, I got the hub off and trying to figure out how to get at the part to clean it off. Is it even possible for a newbie to do??? Hub seems to be one sealed unit.

I took it to Midas a few weeks ago to get a code read and they wanted $2,500 to replace both hubs. They said the truck wouldn't make it to the end of the day and the bearings were shot. Funny, I can't detect any bearing noise or play when I checked the wheel. Love theirBS.

Any thoughts on how/where to clean this??

Thanks, Doug

 

[ol]Raise the vehicle on a hoist.
Disconnect both the front wheel speed sensor harness connectors.
Place a DVM across the terminals of each sensor connector.
Rotate the wheel with hand speed and measure the ACmV's. The reading should be at least 350ACmV's.
If the reading is between 200 and 350ACmV's, remove the wheel, caliper and rotor in order to gain access to the speed sensor.
Remove the wheel speed sensor and plug the hole 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, ScotchBriteâ„¢, 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/N89022217 (Canadian P/N89022218).
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/N01051344 (Canadian P/N993037).
Install either the original sensor or a new one in the hub and secure the sensor. Ensure that the sensor is seated flush against the hub.
Install the rotor, the caliper and the wheel.
Place the DVM across the sensor terminals and recheck the voltage while rotating the wheel by hand. The voltage should now read at least 350ACmV's. [/ol]
You should be able to see a round steel ring with a bunch of square teeth on it.

 

Thanks so much for the reply.

I just did the reading on a hubI got from the wrecker & it was good (as per your instructions). I'll go out and do the same on the hub on the truck in a few minutes.

My question now is: the speed sensor is built into the hub 99 to 01 had this). The connection is with one allen bolt and the other side looks like it's puched in with a steel rivet. Either that or someone has ground off the top of a bolt head. I can grind off the head, but if it's been punched-in, I probably can't replace that without drilling it out and tapping new threads- getting into a real pain. Does this sound right??

Thanks again, Doug

 

I have a used hub sitting on the garage floorI can fart around with tonight and get back to you on it. Mine is from a '00 S10-Blazer.

 

I have the same problem, mine is one little kickback just as I come to a stop. I checked my front ABS sensors, they were clean other than just having some red axle grease on them. I wiped it off anyways, so we'll see what happens. Here's some pics of a new hub assembly, and what a new sensor looks like. All I needed to pop it off was a 5mm allen. Just remove the one screw and carefully wiggle it out (it's plastic, don't snap it)

 

Great pics! Nice job.

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