# ABS kicks in when almost at complete stop



## famouslee99gt (Nov 6, 2006)

I have a 1999 Chevy Silverado 1500 Z71 and am having issues with my ABS. When coming to a stop, the ABS will kick in when under 10ish mph. I started to happen after I changed my driver front wheel bearing. It was a cheap Ebay bearing, so, now, about 3-4 months later, I bought a new wheel bearing and installed it today to see if it changed. Nope. When I changed it a couple months ago, the ABS & Brake light would come on but reset when I would shut the truck off. The ABS pump is not having the typical issue where it runs non-stop, but it kicks in for no reason.


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## overtime (Nov 5, 2009)

Gm has problems with rust built up under the abs sensors. both sides need to be cleaned. Also that cheap ebay bearing might wanna try a better one.


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## famouslee99gt (Nov 6, 2006)

I did replace the ebay bearing today and no change. The ebay bearing was only 3-4 months old. Maybe I have rust under the passenger abs sensor, although that bearing is only a year and a half old.


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## Joesno (Dec 8, 2008)

my 03 does it. just got used to it. so all i need to do id clean the sensor?


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## overtime (Nov 5, 2009)

Yep clean sensor. be careful when you pull it out of hub. You don't brake it otherwise dealer is only place that sells the sensor I think last I knew.


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## 06Sierra (Nov 30, 2008)

There was a recall in some northern states for that issue. Like the others said, it's the abs sensor.


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## famouslee99gt (Nov 6, 2006)

When I got the truck back in April 2006, I had it in the shop for that recall and they cleaned them. I was having issues then, it was just an open recall on the truck and I wanted it done. I'm not sure if they would do it again for free, or if this time I would have to pay since it's been done once.


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## mrfixx (Sep 21, 2007)

*mrfixx*

The proper way is to pull both front abs sensor,clean the sensor..Get a file and remove the rust off the mating surface where the sensor sits..make sure you see bare silver metal,this will tighten up the air gap SO the stater in the hub can be close enough the trigger the magnetic sensor..Apply Greece (not anti-seize has nickel in it and it will trigger the sensor) to the surface and reinstall the abs sensor..your problem is now solved..


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## samjr (Mar 18, 2008)

*my 04 sierra same thing*

abs sensor is $55 here in canada so in the us $40 i wood say but they want $150 aside to cleen them and if they brake then the $55 comes in


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## mcwlandscaping (Sep 8, 2005)

Pull out the abs fuse and be done with it


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## sechracer (Nov 4, 2007)

mcwlandscaping;868395 said:


> Pull out the abs fuse and be done with it


Agreed, I pulled my fuse and dash bulb. No problems since


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## nhgranite (Feb 26, 2009)

had the same problem on my 01.rust built up on the sensor. turns out i needed rotors, pads, calipers etc... anyways. it sucked with the abs coming on every time i stopped. thank god for the allison tranny's gearing. makes brake use minimal.


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## Burkartsplow (Nov 1, 2007)

ABS sensor at the dealer is $130 for oem. I was thinking of doing it myself. How long would it take and how easy or hard is it. thanks. Only one mine is bad, but I thought I would clean both or replace both.Thanks


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## mcwlandscaping (Sep 8, 2005)

I changed the abs sensors in my truck when I was having that issue and it worked for a day then did it again, turned out to be the module...that's why I said to just pull the fuse


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## affekonig (Aug 5, 2008)

Here's the procedure if you want to replace the sensors:

The following procedure provides instructions for repairing a corrosion condition where the front wheel speed sensor mounts on the front wheel bearing assembly.

Raise the vehicle on a suitable hoist and support as necessary. 
Remove both front tires and wheels. 



Compress the front brake caliper pistons. 
3.1. Install a large C-clamp over the top of the caliper housing and against the back of the outboard pad. 

3.2. Slowly tighten the C-clamp until the pistons are pushed completely into the caliper bores. 

3.3. Remove the C-clamp from the caliper. 





Important: It is not necessary to remove the front brake caliper from the bracket when removing the bracket in the next step. 

Remove the two bolts that attach the front brake caliper mounting brackets to the knuckle. 
Notice: Support the brake caliper with heavy mechanic’s wire, or equivalent, whenever it is separated from its mount, and the hydraulic flexible brake hose is still connected. Failure to support the caliper in this manner will cause the flexible brake hose to bear the weight of the caliper, which may cause damage to the brake hose and in turn may cause a brake fluid leak. 

Remove the brake caliper and bracket as an assembly and support it with heavy mechanic’s wire or equivalent. DO NOT disconnect the hydraulic brake flexible hose from the caliper. 
Mark the relationship of the rotor to the bearing hub. 
If equipped, remove the rotor retaining push nuts from the wheel studs 



Remove the rotor. 



Remove the bolt (1) that attaches the wheel speed sensor to the bearing hub. 
Notice: Carefully remove the sensor by pulling it straight out of the bore. DO NOT use a screwdriver or other device to try to pry the sensor out of the bore. Prying will cause the sensor body to break off in the bore. 

Remove the wheel speed sensor from the bearing hub assembly. 



Important: The mounting surface on the sensor must be flat in the next step in order to be mounted correctly on the bearing hub assembly. If the mounting surface on the sensor is warped or bent, the sensor must be replaced. 

Inspect to see if the mounting surface on the sensor is flat. Check the mounting surface on the sensor head for flatness by placing it on the edge of a metal machinist’s scale or other suitable straight edge to measure the flatness. Check the sensor for flatness in multiple positions/directions (minimum 3). 
• If the sensor mounting surface is NOT flat (1), the sensor must be replaced. Proceed to the next step and replace the sensor. 

• If the sensor mounting surface IS flat (2), the sensor IS to be reused. Proceed to Step 16. 





Remove the wheel speed harness mounting clips from the knuckle (4) upper control arm (3) and frame (2). 
Disconnect the wheel speed harness electrical connector (1) from the vehicle wiring harness. 
Connect the new wheel speed sensor harness electrical connector to the vehicle wiring harness. 
Attach the wheel speed sensor harness to the frame, upper control arm, and the knuckle. 



Temporarily plug the wheel speed sensor hole (1) in the bearing hub to prevent debris from entering it when you clean it. 
Important: All rust and corrosion must be removed from the wheel speed sensor mounting surfaces on the bearing hub in the next step. 

Using a wire brush, sandpaper, emery cloth, scotch brite, or equivalent, thoroughly clean the wheel speed sensor mounting surface (2) on the bearing hub to remove any rust or corrosion. 
Using compressed air, remove all debris from the bearing hub surface. 
Using a clean shop towel, clean the sensor and the O-ring. 
Important: While the corrosion inhibitor is drying in the next step, begin performing Steps 3-20 on the opposite side front wheel speed sensor. 

Apply (spray) two thin coats of the specified rust penetrating lubricant (corrosion inhibitor) listed in this bulletin, to the complete sensor mounting surface on the bearing hub. Allow to dry for 3-5 minutes between coats. 
When the corrosion inhibitor is dry to the touch (about 10 minutes), apply a light coating of the specified grease to the complete sensor mounting surface on the bearing hub and to the sensor and O-ring. 
Remove the temporary plug from the hole in the bearing hub. 
Install the wheel speed sensor in the bearing hub and install the bolt. Ensure that the sensor is seated flat against the hub. 
Tighten 
Tighten the wheel speed sensor mounting bolt to 18 N·m(13 lb ft).

Disconnect the front wheel speed sensor connector and place a digital volt meter (DVM) across the terminals of the wheel speed sensor connector. Rotate the bearing at approximately one revolution per second. The minimum reading should be at least 350 ACmV’s. If the reading is less than 350 ACmV’s, the wheel speed sensor must be replaced. Follow Steps 12-15 for instructions on replacing the wheel speed sensor. This step must be repeated after the new sensor has been installed. 
Notice: Whenever the brake rotor has been separated from the wheel bearing flange, clean any rust or foreign material from the mating surface of the rotor and flange. Failure to do this may result in increased lateral runout of the rotor and brake. 

Important: If the rotor was removed using the jack screw method, you must ensure that the hub flange is free of nicks or marks caused by this procedure. Remove all raised nicks or marks before installing the rotor. 

Align the rotor to its original position on the hub and install the rotor. 
Install the caliper and caliper mounting bracket assembly. 
Perform the following procedure before installing the brake caliper bracket mounting bolts. 
27.1. Remove all traces of the original adhesive patch. 

27.2. Clean the threads of the bolt with brake parts cleaner, or the equivalent, and allow to dry. 

27.3. Apply threadlocker to the threads of the bolts. 

Install the caliper bracket mounting bolts. Tighten the brake caliper mounting bracket mounting bolts to the specification listed below. 
Tighten 

• 1500 Series vehicles - 175 N·m(129 lb ft) 

• 2500 Series vehicles - 300 N·m(221 lb ft) 

Install the front tire and wheel assembly. 
Tighten 
Tighten the wheel nuts to 190 N·m(140 lb ft).

Complete Steps 21-30 on the opposite side front wheel speed sensor. 
Lower the vehicle. 
With the engine OFF, gradually apply the brake pedal to approximately 2/3 of its travel distance. 
Slowly release the brake pedal. 
Wait 15 seconds and repeat Steps 32-33 until a firm pedal is obtained. This will properly seat the brake caliper pistons and brake pads. 
Customer Reimbursement


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## overtime (Nov 5, 2009)

Only reason you need to replace them is if they brake just spray FF and you should be fine. Very common problem


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## famouslee99gt (Nov 6, 2006)

Burkartsplow;868699 said:


> ABS sensor at the dealer is $130 for oem. I was thinking of doing it myself. How long would it take and how easy or hard is it. thanks. Only one mine is bad, but I thought I would clean both or replace both.Thanks


I'm not sure how the 2500HDs are, but a brand new wheel bearing from Advanced Auto Parts with ABS sensor is only 100-130, depending on how much warranty you want.

And to some others, I will not pull my fuse. I would like the ABS to work. I'm not going to band-aid it by pulling the fuse


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## RichG53 (Sep 16, 2008)

famouslee99gt : I agree no band aids for me ...Only fixing it right in my book .....
There are reasons they build these SAFTEY devises into these Vehicles .....


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## nascar (Nov 11, 2009)

Pull the sensor and lightly file the face of the sensor and file the outer edge face and the top of the whole where the sensor plugs in. It brings the sensor in a little closer and it will be fine.


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## turbo38sfi (Nov 24, 2006)

Why pull anything? I received the recal from GM on this on my 02 Tahoe. Since it's a safety recall issue, all you guys should be able to call you local GM dealer and have it performed. They look up by VIN to see if the recall has been done yet and if not it should cost you nothing.


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## famouslee99gt (Nov 6, 2006)

Got the truck fixed. Took it to dealer finally and they told me it was actually the passenger side that was not reading to correct speed. I put a new bearing in this afternoon and after a 5 mile trip around the block, I never had any problems. I had put a different known good sensor in it over the weekend and that hadn't fixed it, so the bearing was next. That bearing was only about a year and a half old, but the tone ring inside must have been messed up in some form, but nothing I could see. Oh well, ABS works now and I don't have to stare at the lights on the dash.


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## mkwl (Jan 21, 2005)

RichG53;869499 said:


> famouslee99gt : I agree no band aids for me ...Only fixing it right in my book .....
> There are reasons they build these SAFTEY devises into these Vehicles .....


Just be ready to pay an arm and a leg to get the issue resolved- my truck has intermittent issues with ABS (not this one- just the ABS and BRAKE lights randomly go on and off), but my buddy from school (a certified GM mechanic) warned me- ABS systems are usually a few grand to get fixed if it's the EBCM that's no good...just a heads up...


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## famouslee99gt (Nov 6, 2006)

The truck is fixed though. The tone ring inside the passenger side wheel bearing must have had something go wrong with it and caused the sensor to not read the correct speed anymore. Now that I have a new bearing/sensor assembly installed, no more problems.


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## mkwl (Jan 21, 2005)

famouslee99gt;912084 said:


> The truck is fixed though. The tone ring inside the passenger side wheel bearing must have had something go wrong with it and caused the sensor to not read the correct speed anymore. Now that I have a new bearing/sensor assembly installed, no more problems.


Glad you got it solved! :salute:


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## famouslee99gt (Nov 6, 2006)

I'm glad too, because the one mini snow/ice event we had this year, it was a treat to drive without the abs because they would just lock up, and I didn't care for that again. That was just a dusting and the only thing we've had yet this year. Although it doesn't matter, since I don't have any contracts to plow this year.


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## corkireland (Feb 17, 2004)

That stupid abs problem just caused me an accident over the weekend. Had no problem on my 2000 Chevy Silverado then tried to stop at 8 mph behind a lady and bam! ABS went off and truck could not stop in time. Dry pavement and very very bad timing for that sensor to go bad!!

The recall was issued back in August of 2005 for GM pickups/suvs from 99 to 02 and even some newer vehicles with similar problems.

The problem i'm seeing as I'm researching this is that its a recurrent problem that cleaning alone does not fix. The truck inevitable has the problem again. Seems to be about 4 year increments or less. I'd suggest that anyone who has had the problem, especielly recently make a report to

www.safercar.gov

Personally I think the system continues to be faulty and if GM's supposed fix did not solve the problem, they should be liable for accidnets and replacing it with a safer system.

I'll get off my soap box now! :angry:


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## fordmstng66 (Dec 27, 2005)

06Sierra;868012 said:


> There was a recall in some northern states for that issue. Like the others said, it's the abs sensor.


All they do i remove the sensor, and clean it, then throw it back in. I had that done to my 2000 when i had it.


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## Seaway25 (Sep 15, 2009)

I had that problem in mine. I put in a new bearing and it went away.


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## nascar (Nov 11, 2009)

turbo38sfi;873008 said:


> Why pull anything? I received the recal from GM on this on my 02 Tahoe. Since it's a safety recall issue, all you guys should be able to call you local GM dealer and have it performed. They look up by VIN to see if the recall has been done yet and if not it should cost you nothing.


it is a geographical region recall. My truck was not listed, not every truck is listed even if it is the same class and parts. It is a stupid recall, they are short changing a lot of people.


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## tuney443 (Jun 25, 2006)

.''.Apply Greece (not anti-seize has nickel in it and it will trigger the sensor) to the surface and reinstall the abs sensor..your problem is now solved.. ''

Where would one buy this ''Greece''???:laughing: Wow--I'm not from the spelling police,but that is funny.


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## t.i.b (Jan 17, 2009)

sechracer;868648 said:


> Agreed, I pulled my fuse and dash bulb. No problems since


how do you get at the dash bulb?


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