2003 Sierra Brake Noise

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  #1  
Old 09-30-09, 10:02 AM
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Lightbulb 2003 Sierra Brake Noise

Hello, I have a problem that I can't seem to figure out yet...serveral weeks ago, my truck started to do something funny while braking. It feels similar to when the ABS kicks in and the pedal moves on its own, BUT the abs hasn't been kicking in. There is a vibration in the pedal, a noise that goes along with it (not a metal to metal noise) and it doesn't appear to be affecting braking ability. The truck only has 50k on it, so you can tell it only gets occasional use. I have already replaced the rear brakes last year, due to non-use and rusting out. So I figured the fronts just went bad too. This weekend I pulled the old pads and rotors off and of course, they were bad, one of the pads was wore almost down to the metal backing, and rotors were too far gone to turn.

So, new pads, rotors, I figured I was good. Went a day without the noise/vibration...and then it came back. I'm not sure what this could be, the caliper pins were nice and greased up, so the caliper should be moving smoothly on them...

I am getting the noise/vib when I roll up nice and slow on a stop sign (I don't like to brake hard, my wife says it's almost painful how slowly I stop most times). It also doesn't happen every time, but if I brake with force, there is no problem.

It almost feels as though the brakes are skipping or sliding (that's the best I can do to explain it), but there is no loss of stopping power when the noise/vib occurs.

Any ideas???
 
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  #2  
Old 09-30-09, 03:46 PM
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Location: santa fe /texas
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sounds to me to be what is refered to as non requested abs application.
usuals caused bu a speed sensor problem.
can be difficult to diagnose-without proper scan tool to watch speed sensor signals.
look for a loose bolt holding one the 3 sensors
a worn place in the sensor wire
metal contamination on the end
take the front calipers off-watch the seensor ring as you spin the rotor-no cracks-or left right runnout
possible - remofe ring gear cover look for damaged toothed ring
ring rear_carrier loose-moved left rt by hand
 
  #3  
Old 09-30-09, 03:51 PM
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Would this "non requested abs application" cause any of the dash lights for the abs to trigger on??? I haven't seen any lights on the dash light up when the problem occurs...
 
  #4  
Old 09-30-09, 03:56 PM
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not untill the processor looses the signal all together.
or the faulty signal becomes too eratic
or the difference between the 3 signals reaches a predetermined value(abou 5 mph at 30 mph)
that is why you cant put bigger tires on the rear
 
  #5  
Old 10-01-09, 04:07 AM
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Just one more question...would this "non requested abs application" actually engage the anti lock brakes??
 
  #6  
Old 10-01-09, 05:31 AM
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Quick way to tell if it is the abs, pull the abs fuse, under hood fuse block, think its a 40 amp maxi fuse ,orange, or disconnect the connector with the large red and black connector at the abs motor, (drivers side under truck bout 1/2 way back lots of brake lines going to it and 2 connectors)
There is also the posibility that you have a front hub going south on you, jack up the front end and check for "play" on each side. I will do a search for any bullitins gm might have related to your problem and let you know.
 
  #7  
Old 10-01-09, 05:34 AM
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found this as some one else said:
This bulletin is being revised to add the 2007 Silverado/Sierra Classic models. Please discard Corporate Bulletin Number 03-05-25-007C (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 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.
Parts Information
Part Number
Description
Qty

89022217

(Canadian P/N 89022218)

(Package of 2 cans)
Rust Penetrating Lubricant

(Each can will service 50+ vehicles)
1

01051344

(Canadian P/N 993037)

(Package of 12 tubs)
Wheel Bearing Lubrication - Tub

(Each tub will service 25+ vehicles)
1
 
  #8  
Old 10-01-09, 07:56 AM
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Okay, I just went out and took the fuse out (60amp, yellow) from under the hood. I didn't have any braking problems. I wouldn't have guessed it was the abs...

thanks for your help...I will start digging into the abs and see if I can't get this resolved. I will report back with info this weekend when I have time to get working on it.
 
  #9  
Old 10-01-09, 08:09 PM
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as stated by the above member-look for loose wheel bearings-other obvious stuff.
is this a 4x4-where the ft wheel bearing is in the steering knucle-not the rotor /hub?
 
  #10  
Old 11-10-09, 06:01 PM
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Just an update if anyone is interested...I finally had some time to work on the truck...turns out that both sensors tested poorly using DIRTWRKZ instructions, tested around 250ACmV. Decided that if I'm going through the trouble to remove the old ones to try and clean them, I might as well just get the parts and replace them with new ones...best price I could find was about $120 bucks for the pair...then I found a great deal on the complete hub/bearing assembly which actually comes with a new abs sensor on it too, for only $160 for the pair. So, the front end is getting some work done and I will have new hubs/bearings/abs sensors in a couple days once the rust penetrating liquid does it's job and I can get the old hubs off.
 
  #11  
Old 11-15-09, 12:48 PM
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Okay, I don't know if anyone is listening or not, but here goes...

Can anyone give any helpful hints on removing the hub/bearing assembly from my truck??? Obviously, everything is aged and rusty and stuck on really well...I had to hit the 3 bolts with wd40 multiple times over 4 days before they would give...they are loose now. The axle nut was not a problem, those are loose now too. I just cannot get the hub off the truck...any ideas???

I wouldn't have guessed that removing 3 bolts and 1 axle nut from each side of the truck would have been this frustrating of a job

Thanks in advance for any input...
 
  #12  
Old 11-18-09, 07:20 PM
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sorry been out of pocket for awhile, i will look at one tomorrw and let ya know the best attack plan
 
  #13  
Old 11-19-09, 03:25 AM
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Sounds good. My next thought is it to take the knuckle off an attack it that way to pop (that word makes it sound so easy) the hub/bearing out...but that seems like it's getting a little out of my DIY range. Hopefully you can come up with a better solution. Thanks.
 
  #14  
Old 11-20-09, 06:13 AM
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I swear i sent a response to ya yesterday, anyway. front end guy says either beat it off or replace the spindle. I/we use gm
heat riser penitrant for everything, best stuff i have ever seen for removing rusted/stuck on parts.
 
  #15  
Old 11-22-09, 05:16 PM
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JOB DONE...Thanks for the help. Turned out to be quite a job. Ended up taking the knuckle off and pressing the bearing out. Of course the upper and lower ball joints were very well seated in place and took some "persuasion" to break free from the knuckle. Then it was all I could do to have my father in law's 12ton press take the hub out of the knuckle, but, everything is done now and the brakes work great...no more non requested abs application...

I'm glad this project is done.
 
  #16  
Old 11-24-09, 03:09 AM
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Can anyone give any helpful hints on removing the hub/bearing assembly from my truck??? Obviously, everything is aged and rusty and stuck on really well...I had to hit the 3 bolts with wd40 multiple times over 4 days before they would give...they are loose now. The axle nut was not a problem, those are loose now too. I just cannot get the hub off the truck...any ideas???ac compressor
 
  #17  
Old 11-24-09, 03:16 AM
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Sounds good. My next thought is it to take the knuckle off an attack it that way to pop (that word makes it sound so easy) the hub/bearing out...but that seems like it's getting a little out of my DIY range. Hopefully you can come up with a better solution. Thanks.
ac compressor
 
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