ABS problem on denali - apparently never seen before...

A week or so ago I was driving my 2000 Denali gradually coming upto a stop sign. Almost stopped I felt the brakes release and grab again (in the brake peddle) and also heard the abs come on. Over the past few days I have had some close calls such as #1. reversing out of driveway and the abs comes on. The truck continues to move after applying brakes. (grabs and releases and then grabs again after pressing harder on brake peddle.)#2 this is the shocker I was driving into a parking lot and the abs comes on ( i heard the abs noise) and i haven't even applied the brakes. I took the truck to my mechanic and he test drives it and reports the abs came on just driving down the road, at a drive-thru, and just sitting in the truck while idling.
If anyone has/had this problem or has any suggestions it would be greatly appreciated!!!

You are going to need a front wheel bearing / hub assembly or two.
Your dealership will know how to diagnose which wheel bearing it may be.

The wheel speed sensors are built into the hub. As the hub/bearing wears out, it allows the reluctor (pick-up) wheel to move away from the wheel speed sensor. This causes too much of an air gap, and the wheel speed sensor sends an erratic signal to the EBCM (electronic brake control module).

This in turn looks like a wheel slip and the ABS is energized and engages. This usually happens at low speeds, because the signal is more erratic at lower speeds.

The only true repair is to replace the bad wheel bearing/hub assembly. GM does explain a removal and readjustment procedure, but I haven't seen that fix last more than a couple months before the same concern re-arises.
Hope this helps.

A couple questions about the wheel bearing thing. I understand that the sensor/reluctor spacing is an issue,but it is my understanding that ABS cuts out at 10mph (or you would never stop the car). If the ABS activated while sitting still ,there should be no speed sensor reading from any wheel.It has been my expieriance that a WSS that eractic would turn on the ABS lite. GMCtech-I ask these questions to help myself later when I see this problem. If you can give me more specifics on the hubs causing this problem, I would appreciate it.

After speaking with my mechanic, he is sure it is the front pass. side wheel speed sensor. As for the abs coming on while at a stand still the mechanic, plus two others as well the gm tech guy have never encountered or heard of the problem. The gm tech guy suggested that my mechanic try a number of different things to try and resolve problem ex: replacing the pass side wheel sensor then testing truck plus a list of other things. The only problem is the gm tech guy suggests trying all of these things but I am on the hook for the bill. this trial and error could end up costing alot of $$$ and maybe still won't be fixed.
I phoned gm customer assistance centre today and explained things to them re: speed senors and abs coming on while at a standstill. there response was the "speed sensor" recall does not apply to my truck and as far as the abs coming on at a stand still she had no response except that they could not offer any help.

Bronco2 (and others that may be looking)

If the ABS is in a current engagement mode it will continue to activate all the way down to 0 mph. As far as it continuing after the vehicle is at a complete stop, I too am at a loss.

My guess is there may be two issues at work here- 1. A bad wheel bearing, and 2. An internal electrical fault in the EBCM that is causing continued engagement of the ABS motor.

Hope this explains a bit. But, as far as the ABS coming on at a stand still :dunno: Maybe it is just looking for some attention. :attention

I just spoke to my mechanic this morning. A RECALL has just been posted last week. RECALL #04094 "Engagement of Anti-lock brakes at slow speeds. Service Bulletin # YR138016
I know that the 2000's are included yet I was told that it only is for a certain batch of VIN #'s. I phoned the GM dealer and he told me, it does not apply to my yukon vin# yet I am having that exact same problem (which started a few weeks ago.) Figure that one out. Frustrating!!!!!!!!!

smitsz 1...I have the same problem on our 2000 Yukon XL. Just talked to the GMC service dept. and they said it's a "Front Wheel Speed Sensor Corrosion" recall. It's a cleaning/wire harness replacement apparently.

Even tho we also have a 2000 Yukon XL, our vehicle doesn't fall under the recall either. The service guy couldn't tell me why.

Does anyone know who to call to let GM know other vehicles that aren't included in the recall are experiencing the same characteristics?

Just got off the phone with GM cust. assistance and spoke to a rep.in Oshawa again! I explained I would like to speak with a supervisor. I was refused. I once again explained the problem I am encountering with my ABS system - the abs coming on at low speeds or even while at a standstill I mentioned I heard a recall re: ABS system was announced last week "Engagement of Anti-lock brakes at slow speeds" recall # 04094 service bulletin # YR138016. The rep asked me my vin # and she said I was not included. I said it does apply to 2000 Yukons does it not? The rep did not want to answer the question. In fact she was quite evasive speaking a bunch of mumbo jumbo and beating around the bush!Finally, I asked the question repeatedly until she answered. Her reply Yes, it does include 2000 yukons. Yours unfortunately is not included. I replied lets get this straight GM has admitted their is an ABS problem with the speed sensors and ABS coming on at slow speeds issued a recall, I have this exact problem, own a 2000 yukon, but I am not able to have this fixed...
Something wrong with this????

I can't take credit for this information. It was listed on another site/forum by a highly respected poster, but apparently the recall is localized by vehicle and geographical location. Following is the exact quote:
"General Motors has decided that a defect which relates to motor vehicle safety exists in certain 1999-2002 Chevrolet Silverado, 2000-2002 Chevrolet Tahoe, Suburban, 2002 Chevrolet Avalanche, 1999-2002 GMC Sierra, 2000-2002 GMC Yukon, Yukon XL vehicles located in Ontario, Quebec, Newfoundland, New Brunswick, Nova Scotia, and Prince Edward Island."
Why a "defect which relates to motor vehicle safety" would be limited to certain regions is beyond me. I think a silent recall by ALL affected would be the wise choice. Of course, I don't have all the details, just the problem (apparently).

Hi, I think it has to do with the corrosive environment (cold, salt water) that is apparently limited to Eastern Canada.
May be not enough people in Western Coastal Canada?
They may have stricter laws up North?

I had the same experience on another topic with GMC assistance: Evasive and of no use, without giving any clear answer, just beating around the bush and then saying too bad for you...
They make Motor Vehicles look like a joy to deal with.

Take care, Eggert :bananasmi

I live in southern ontario, near port dover (on lake erie). the recall still does not include me....

When I call, I'll make sure to quote that ""General Motors has decided that a defect which relates to motor vehicle safety exists..." and ask them why it's been deemed my safety is not important.
I have to put a disclaimer out there tho...I haven't been told by a GMC service dept. that this IS my issue. I am just experiencing the same/similar symptoms.
It's just burns me that if it is a "safety" defect, that all aren't covered by a silent recall.

smitz,
You can go to www-odi.nhtsa.dot.gov/cars/problems/complain/ to file a complaint if you like.

I just got off the phone with transport canada "defects investigation dept." The gentlemen I spoke to has actually experienced the ABS problem on a 1500 series pickup. They are performing a investigation... More to follow...
Anyone else experiencing the ABS sensor problem who lives in canada is encouraged to report their problem.
Transport Canada phone # is 1-800-333-0510 and ask for the "defect investigations dept".

I have found GM to "limit" their recalls when prior years are affected too.

I have a 1989 Firebird with a leaky gas tank.

GM recalled 1990-1991 firebirds with a leaky gas tank. They somehow get away with "narrowing" the recall range.
and I know for a fact my gas tank leak was the exact same as the recalled units.

and to sit and argue with GM is useless.
the filing a complaint method will probably go futher.