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ABS kicks in randomly, but no code

Discussion in 'Lifted & Offroad Suspension' started by Mindi51982, Sep 4, 2009.

  1. Mindi51982

    Mindi51982 New Member

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    ABS kicks in randomly, but no code (issue with stater?)

    So I have an interesting issue. Apparently it's common with my truck ('98 5.7L). The ABS will randomly kick in but it doesn't kick off a code. When I'm slowing down and almost completely stopped, the ABS kicks in. If I pump the break once, it goes back to normal. A guy that I work with has a plow truck that does that. It's been happening for years on that truck but hasn't caused any issues. I think they eventually just pulled the fuse for ABS and his issue went away. I guess I should try that. If it doesn't kick off a code, I have no idea what sensor would be bad. Anybody run into this issue and any advice as to how to fix it? It doesn't bother me now, but in the winter on icy roads it'll be a pain. Especially in Indiana...they don't salt the roads, leaving a very icy mess. Thanks!:great:
    Last edited: Sep 10, 2009
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  2. dano8928

    dano8928 New Member

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    Yeahhhh youre not going to get a code. Most likely its your wheel bearings. I had the SAME thing happen last summer. I took the fuse out also for a while but im glad that i took it in the garage because we took the wheel off and the mechanic i was working on it with said he would have been suprised if my wheel stayed on for one more day. There was nothing left to the bearing. it came out in pieces. So start there. I dont know why it screws up the Anti Lock but it does. I almost hit a stone wall because of that haha. But like you said i pumped them once and they worked fine. Good luck and let me know if that works.
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  3. Mindi51982

    Mindi51982 New Member

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    Okay good thinking. We have an on-site mechanic so I'm going to see if he can look at the bearings for me. That's a good place to start. Thanks! :great:
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  4. dano8928

    dano8928 New Member

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    No problem. I just got done looking at your mudding pictures with your ZR2. I had a 94 Blazer those things kick ass in the mud! haha let me know what you find out with your bearings.
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  5. Mindi51982

    Mindi51982 New Member

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    Had the mechanic at work look at it and he thinks it's something with the stater? He thinks it's like a disk with nodules on it that the sensor reads. If a couple nodules are rusted together, then the it can't sense to brake and the ABS will kick in. But he isn't sure if that's what it is called. It's either on the rotor or in the bearing. Anybody know?
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  6. Jimmiee

    Jimmiee New Member

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    It's called a reluctor or tone wheel. I believe you have found your problem. Can you clean it up so the sensor reads all the teeth? Even 1 tooth missing or a little mud can cause the ABS to kick in.
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  7. Mindi51982

    Mindi51982 New Member

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    Okay. Can you help me with where this is actually located? Is it behind the rotor or is it in the wheel bearing? I have a '98
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  8. Jimmiee

    Jimmiee New Member

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    Here's a picture. The sensor reads the teeth inside the rotor.

    Attached Files:

    • WSS.jpg
      WSS.jpg
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  9. 2COR517

    2COR517 New Member

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    A bad wheel speed sensor will cause the same problem. Your best bet is to get a good scanner on there and drive it. You need to see both wheel speeds and the rear driveshaft speed at once as you drive.

    That will help isolate which wheel is giving you trouble. My ABS computer was bad, so I pulled the fuse. All better now. Except that stupid yellow ABS light on the dash LOL.
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  10. 2COR517

    2COR517 New Member

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    Ahh, yeah. No. I'm gonna have to go ahead and disagree with you. I'm just not sure about that.

    Are you an Office Space fan? I love Bill Lumberg!

    Actually, I do disagree about the wheel bearings causing the issue. It's far more like that the stator and/or WSS was cleaned out in the process of changing your wheel bearing, in effect fixing the ABS issue at the same time.
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  11. Mindi51982

    Mindi51982 New Member

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    Okay so the entire rotor needs to be replaced?
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  12. Jimmiee

    Jimmiee New Member

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    No, not necessarily. Did your mechanic see a problem or was he just guessing? I would have someone check it that knows how the system works. The best way to check it is with a scanner. With a scanner you can see if the sensor is working or not.
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  13. Mindi51982

    Mindi51982 New Member

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    He was just guessing. He wasn't sure where reluctors were located. He just does general mechanical work for the company. He doesn't have a scanner or anything like an actual dealer at a shop would have. Is that part of the free brake estimates that you can get?
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  14. 2COR517

    2COR517 New Member

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    You should take the vehicle to someone with more experience with brakes, ABS in particular. You could try a Midas type shop and see if they will scan it for you. If not, look for an independent shop that doesn't have enough parking area for all the cars that need work. That usually means they are good, and fair.
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  15. Mindi51982

    Mindi51982 New Member

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    That's a picture of a 2wd. I have a 4wd 1/2 ton.
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  16. Jimmiee

    Jimmiee New Member

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    The sensor works the same way on your truck. Do you understand the reason for getting a scanner hooked up to your truck? Right now it's just a guessing game.
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  17. Mindi51982

    Mindi51982 New Member

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    Yeah..it makes sense. I just talked to my bud. He has access to a scanner and is going to take it home with him next week to test drive it and to figure out what's going on with it. So with that issue it wouldn't send out a code right? I have a Hypertech Programmer and it does read codes, but I don't think that would pick up a code since it's an ABS issue?
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  18. Jimmiee

    Jimmiee New Member

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    Right. You need a scanner that can read data as well as codes. The data will show each wheel speed. This is how the ABS knows which brake to pulse. If the ABS sees a wheel speed that's slower, then it knows that wheel has lost traction and is starting to skid. It then releases the brake on that wheel and as soon as the speed equalizes it starts braking the wheel. If the wheel skids again it releases and brakes again. You feel this in the brake pedal when that happens.
    Now if a speed sensor is acting up because of a missing tooth, mud, loose wheel bearing or whatever, you feel the ABS come on when braking. If the computer sees different wheel speeds with the brake off then it sets a code for the particular wheel and light up the ABS light.
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  19. Mindi51982

    Mindi51982 New Member

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    :great:

    Makes perfect sense. Thanks
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  20. Mindi51982

    Mindi51982 New Member

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    I was talking to a buddy and I found out the official diagnosis is called....ABS false activation. I may not need to replace the bearings afterall. Most of the time the false activation is caused by corrosion and build up on the sensor. Next weekend I'm going to take it apart and check the o-rings and the sensor. I'll try to clean up what is corroded, while ensuring I leave as much good metal as I can. I was told to make sure i watch the air gap. I'm not sure how to measure that or what it's suppose to be, so I have more research to do yet.
    #20

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