Pulsating abs

This is my second post about my ABS problem.
At low speed my abs seems to pulse and come on even when the road conditions are perfect and their is no loss of traction whatever.
The abs sensors are approx. $200.00 Canadian and I have been warned that I would possibly have to replace the backing plate through which they are mounted.
I have to find the one that is creating the problem. Does anyone have any suggestions on doing this? If I disconnect the sensor at the closest connector will it show a failure on one wheel but still operate the others?
Any advice is appreciated in this matter as I want to get it resolved while I am swapping rotors and pads as I also seem to have a slightly warped rotor.
Thanks for your help in this matter,
Blair
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There is a TSB on this. I quote:
Brakes - Antilock Brake Activation at Low Speeds
Bulletin No.: 02-05-25-006A
Date: December, 2002
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
This bulletin is being revised to change model information. Please discard Corporate Bulletin Number 02-05-25-006 (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 speed sensor mounting surface on the hub to remove rust and corrosion.
Important: Make sure that the sensor sits flat on the hub. If the sensor flange is distorted, replace the sensor.
8. Apply a thin layer of bearing grease to the surface prior to sensor installation.
9. 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.
10. Install the rotor, the caliper and the wheel.
11. Place the DVM across the sensor terminals and recheck the voltage while rotating the wheel by hand. The voltage should now read a least 350 ACmV's.
-tih
--
Don't ascribe to stupidity what can be adequately explained by ignorance.

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I've got a 99 jimmy, i've had no problems, only problem I have is the ABS activating when trying to stop at a sandy intersection after a snow, I dont get stopped. Thats why I popped the hood, got into the power box and yanked the fuse. Now I have no more worries or ABS.
writes:

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From my experience, and others I have talked with about ABS, it doesn't work for squat on ice, sand, or a combination of the two. Wet and dry roads is about the only place they seem to work as they are supposed to.
I have stopped 50+ feet sooner than ABS equipped domestic and import cars and trucks of various years wit a Dunlop GT Qualifier tired '74 Cutlass on icy roads.
I don't believe in ABS or trust it... I am with Adam...pull the fuse!
writes:

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Interesting story to back that up...
An older dude in the neighborhood that me and a friend worked for back in high school decided he was going to teach us how to *really* drive.
One day while we were going down a 4-lane he stated that, if it came down to it, one should be able to slam the brakes and cut the wheel, slide sideways through a break in the median, and come out into oncoming traffic having executed a 180 on dry concrete. Not that you'd necessarily need to, but more or less just to demonstrate control of one's own vehicle. We laughed...That was a bad mistake, and at 45mph, he proceeded to prove his point...in a high-top Ford conversion van.
Needless to say, the guy really knew how to handle his vehicle and depended entirely on being able to predictably lock up and unlock the brakes when needed to do controlled sliding and skidding.
A couple of years later he came home all freaked out. He said he'd almost ate it in a wreck. While trying to do his usual thing to get out of harm's way, the ABS kicked in and prevented him from sliding. He had no ability to control the vehicle because it simply didn't react the same.
I guess it just goes to prove that it all comes down to the driver, and their knowledge of the handling characteristics of their vehicle.
~jp
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Same experience my self, I've always owned a vehicle without ABS and now we got this 99 Jimmy, and it has 4 wheel abs I DONT like it and if I ever buy a vehicle with it again it will ALWAYS be disabled.... Like I've said before I like having control of my vehicle with my foot, not some undereducated computer. We had an '06 Cobalt in December for a rental car, it had ABS and it was the same way with that car, if you came to an intersection with a little sand or gravels on it from the snow trucks, or even salt, they kicked in and caused you to run the stop sign.
"Shades" <shades_1970(at)netins(dot)net> wrote in message writes:

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Lets face it...ABS was developed for those people who are clueless about opperating a motor vehicle. i for one know that if my truck is sliding and nothing happens when i steer the wheel it is most likely because the wheels are not turning. cars are funny that way, wheels are funny that way... they need to be 'rolling' in order to controle the vehicle
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Adam wrote:

    The ABS in my 93 Buick Park Ave worked good even in the Snow. The ABS in my 98 Buick Century sucks.
    Last winter a inch of fresh powder on the ground. I have a green light approaching a intersection at 35 MPH (in a 55 zone). Some idiot runs the light and stops in the middle of the intersection. I applied the brakes, Low-Trac light, vehicle sliding. I left off, drop from OD to 2nd gear. Re-apply brakes lightly, causes vehicle to slide. I start applying the park brake (4 notches) and drop to first Gear. I stopped 5 feet from the passengers side door of the car sitting in the middle of the intersection. I still have a green light (and legal right of way).
    The guy behind me wasn't so lucky. He slid his Mazda in to the ditch trying to steer while braking.
    Any time Im on slick roads (rain, sand, snow, ect) and I apply the brakes I get the Low-Trac light. The brakes modulate, and the braking distance is increased. Releasing the peddle and re-applying with in 4 seconds does not do much good.
    Basically it comes down to a piss-poor system design. Charles
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Blair wrote:

I have had the ABS pulsing brake problem at low speed (5 mph & less) 3 times.
Twice on the left front (2000 Z-71 4x4 Silverado) & 1 time on RH front.
Prob was the wheel speed sensor gone bad... $62 ea US GM Parts Direct...
Dealer fixed it under the 6 year GMPP warranty all 3 times....
Prob is you lose your low speed braking at Stop signs & in Gas stations.
Not a good feeling. All is fine now... but I expect another ABS
sensor purchase in a couple years....
I know the feel of the problem... Pulsing on dry pavement under
low speed braking AND no brakes (auto brake release at low speed too).
A chevy or GM dealer can easily spot the 'which side problem' by doing
a test drive with the GM computer plugged in... The computer
reads both the speed sensor output voltage as the wheel spins....
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I have a 2000 Silverado with this problem, but I received a "Recall Notice" for this problem about 2 months ago. The recall only covers owners that live in high salt or corrosion areas. I guess if you buy a truck in the South and move North your on your own.
Al

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ajtessier wrote:

Yes, correct... but I live in Wisconsin & we were NOT included on
the GM ABS recall Notice Letter.... Had 3 'bad' ABS speed sensors
so far replaced under Warranty however..... Go Figure??

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I just did 500 crunches, and my abs are pulsating, too. :)
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I refuse to buy any vehicle with computerized brakes, shocks, etc... don't like cruise control, rain "sensing" wipers, individual "climate" control, or any of that junk. Just something to make the dealerships more cash with useless repairs. Don't even like AC, took it off my '86 Silverado... I've got electric windows, so I control the "air" without even leaning over in the seat. :-)
GC
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