Brake Problem?

[cshupe]

I have a 99 4x4 Yukon that at slow speeds only has a brake issue I can't put my finger on. Right before you come to a complete stop the pedal pulses almost like an ABS feel even. Last night I turned into a parking spot and the pedal went to the floor and I came about an inch from hitting the car in front of me. I drove it home after that and they worked fine? Any suggestions?
Thanks,
Chris

 

[ERIC95TAHOE]

how are the wheel bearings?

 

[19Yukon97]

Is there any noises when this happens? I had an abs light on awhile ago. My dad bought me two new front abs sensors and the light went off. the next day i drove to a fastener company for some bolts... i pulled into the parking lot... i turned left and applied the brakes to go into a parking spot. i kept going forward (not what i wanted to do) and there was a loud vacumning sound almost like a schreeching... good thing i havde good reflexes i slammed on my parking brake before i came 2 inches from the brand new fastenal truck... i went home and took the sensors off and took them back to oreilly autoparts... come to find out the hispanics around here tend to buy a sensors for a car and then take the old one off and clean it really well and put it back in the box and return it and get the money back while still having the good one on their car. So the one i had on their was bad but it wasnt throwing the abs light code. Which the guy said it didnt turn the light one because it was techinically "NEW" to the computer on the truck. Might check on the abs sensors...
Hope this helps man. This is just what happened to mine and the story that went with it...

 

[bowtiefreak]

Same thing happened to mine, one of the front ABS sensors is bad

 

[foreverfalcon40]

What about ditching the ABS and pulling the fuse from under the hood?

 

[bowtiefreak]

that will tell you if it is the ABS system for sure.

 

[99Yukon_Z71]

Chris, check the exiter rings to make sure they are clean and free of metal shavings and debris. You didnt mention if you had any codes in the ABS Module. If you do, start from there.

Oh and Nikko, I would try to abstain from blaming just the"hispanics" as the ones doing fraudulent returns, because guess what?!?! When I worked at Oreilly's we got "caucasians" doing the same ****. Race dont matter!! So watch out what you say and how you say it, it will save you many asswhoopings.

 

[SunlitComet]

Brakes - Low Speed (Below 5 MPH) ABS Activation 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.

 

[cshupe]

I had to replace a sensor on my wifes 95 Burb at one point as well. But on her car it triggered a light on the dash, i can't remember if it was abs or service engine but on this yukon I have nothing showing on dash.

 

[SunlitComet]

Usually if your abs activates without a light at the same time it is because it sees a lock up condition that it does not think was caused by an internal error like a sensor malfunctioning electrically.

---------- Post added at 01:13 PM ---------- Previous post was at 01:12 PM ----------

so a dirty sensor may not trigger a light.