2003 4WD 4dr Blazer. Approx 65000 miles. Due to living in the land of winter and sale a rear brake caliper stuck and ate a rotor. Took to a local brake shop.

Replaced both rear calibers with rebuilds, installed new rotors and pads.

Front rotors has some surface rust on them from sitting for 6 months but no wear and plenty of metal. Just put in new pads on the front.

Ok so the new quirk is when slowing down to a nothing at a normal stop with very light pressure on the brake pedal just before the rolling stops the anti lock brakes with pulse a couple time. Does not happen at every stop, just some of them.

I have not been in any terrain where I could actually lock up the brakes and see if the anti locks actually work. I guess I could do this on gravel the next time I am out. Any opinions?

 

That is rust under the wheel speed sensors pushing them further away so they don't read properly at slow speed. There is a TSB on this. Common problem in the rust belt. My 2001 had this problem when I first bought it and I know it is un-nerving at first and then very irritiating after you know what it is.

More than likely you can remove them, clean them up, and they will be fine at zero cost. But be careful not to get any junk down in the sensor hole when cleaning or you will be replacing a lot more expensive part. I packed the sensor hole tightly (not deeply) with paper towel before cleaning - then pulled it out with needlenose pliers when ready to put the sensor back in. Also be careful with the sensors when removing them as they are plastic and fairly delicate.

On mine, instead of the specified GM corrosion inhibitor and grease, I used a known excellent corrosion inhibitor grease for protecting metal on collectable firearms during extended storage (because I had some). (for salt water fishing reels) would work well also. Please be advised that WD40 and other water-displacing penetrating oils WILL NOT protect against corrosion. Still OK after 1 year.
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Bulletin No.: 02-05-25-006B
Date: January 05, 2006
TECHNICAL
Subject:
Antilock Brake (ABS) Activation At Low Speeds (Clean Wheel Speed Sensor Mounting Surface)

Models:
1999-2000 Cadillac Escalade
1995-1999 Chevrolet Silverado (Old Style)
1995-2000 Chevrolet Suburban, Tahoe (Old Style)
1995-2003 Chevrolet Astro Van, Blazer, S10
1995-1999 GMC Sierra (Old Style)
1995-2000 GMC Yukon, Yukon XL (Old Style)
1995-2001 GMC Envoy, Jimmy
1995-2003 GMC Safari Van, Sonoma
1995-2001 Oldsmobile Bravada

Supercede:
This bulletin is being revised to update the correction and warranty information. Please discard Corporate Bulletin Number 02-05-25-006A (Section 05 - Brakes).
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 wheel speed sensor mounting surfaces.
1.Raise the vehicle on a hoist.
2.Disconnect both the front wheel speed sensor harness connectors.
3.Place a DVM across the terminals of each sensor connector.
4.Rotate the wheel with hand speed and measure the ACmV's. The reading should be at least 350 ACmV's.
5.If the reading is between 200 and 350 ACmV's, remove the wheel, caliper and rotor in order to gain access to the speed sensor.
6.Remove the wheel speed sensor and plug the hole to prevent debris from falling into the hub during service.
7.Clean the wheel speed sensor mounting surface using a wire brush, sand paper, emery cloth, ScotchBrite(TM) or other suitable material. Be sure to thoroughly clean the wheel speed sensor surface. There should be no rust or corrosion.
8.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.
9.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 (Canadian P/N 89022218).
10.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 0-ring prior to sensor installation. Use ONLY Wheel Bearing Lubricant, P/N 01051344 (Canadian P/N 993037).
11.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.
12.Install the rotor, the caliper and the wheel.
13.Place the DVM across the sensor terminals and recheck the voltage while rotating the wheel by hand. The voltage should now read at least 350 ACmV's.

 

Thanks for the information.

 

Les, all of that info is already in a tech article.

 

Understood. I guess I'm guilty of not typically going outside this particular part of the forum very often to see what is there. BTW, thanks for them!!

Here's a suggestion. How about making the tech article index as a sticky in both the 1st gen and 2nd gen tech forums, and listing the spark plug info and fuel pump diagnosis as part of it. Yes I know it's already in the other place, but if you really want the tech articles to be seen and used........... seems like a lot of people hang out in and keep going back to certain places (like me).

 

We used to have a stickie for the tech article section in each sub-forum, but people complained about them taking up too much space. We can try it again, but for the most part, people are blind to the information that is here and in too much of a rush to search.

For instance, you searched a completely separate website to find the information you posted. It doesn't make a whole lot of sense to me, but I know what is here as I read pretty much every thread posted on this site so I don't really spend a lot of time looking for things when I need to point someone in a direction.

 

I know that someone will always complain, but I'm suggesting getting rid of two stickies (especially the spark plug one) and only putting one sticky back that contains links to all tech articles. Then I suggest leaving that as the only sticky in the 2nd gen tech forum and do something to draw attention to it.

Please remember that some of us don't know the forum nearly as well as you do. The Blazer Forum is way too big for most of us to follow everything that has been posted - or even currently what is being posted. I generally sit here in the 2nd gen forum and try to help answer any questions I feel I am qualified to comment on. Then I read the other posts to try to learn something new. However I agree there is a lot of information in the tech links that should be referenced whenever possible. My subscription to the on-line info will end shortly and I certainly don't intend to scan my factory shop manuals to post here - so this tech info will be referenced by me as much as possible in the future. Question is how to get the tech information recognized by as many members as possible.

I say if someone complains about having one sticky in a forum - then let them complain. For whatever reason, I had never found or noticed the tech article list before today.

 

Thank you this is what my 2001 Blazer does! Tires place kept saying something leaking onto brakes put hundreds into repairs never fixed it even replaced back end he put Jeep back end on my Blazer! Not sure about this must be ok as it still runs!