Unwanted brake anti-locking...

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  #1  
Old 11-29-04, 08:55 PM
cheapfurcoat
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Unwanted brake anti-locking...

I have a `99 Ford Ranger XLT 4x4 with 4 wheel anti-lock brakes. It is a 3 liter 5 speed and has 48,000 miles on it.
When coming to an easy stop, at the last two feet of travel the anti-lock pump comes on. When hard stopping it does not. This problem started as a once in a while thing but has escalated into all the time now.
This past weekend I replaced the front pads, had the rotors turned and put new shocks on all 4 corners. I bought a front ALB sensor from Ford thinking that I could disconnect the sensors one at a time to figure out which was bad.
This does not work. Disconnecting either one of them stops the problem but illuminates the anti-lock brake light in the dash.
How do I determine which sensor is bad?
 
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  #2  
Old 11-29-04, 09:07 PM
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could be a bad wheel bearing. At least that is the similar cause on some late 90s Chevy S-10s.
 
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Old 11-30-04, 02:15 AM
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Well, disconnecting a sensor disables the system so that's why the problem goes away. What's happening is that one of the speed sensors is reading zero speed before the rest.. Now, the problem is to determine which one and why. The normal procedure wouild be to use a scanner and "snapshot" the data at the moment it occurs. Unless you want to just start changing sensors that may be good, this really should go to a shop equipped to solve the problem. As the earlier poster said, a loose wheel bearing could also cause it but that would be pretty easy to check.
 
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Old 11-30-04, 04:10 AM
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Since you already own the sensor try it on 1 side and if it doesn't help try it on the other if you can remove them without breaking them.You would be interested to know it may only be rust between the sensor and the mounting area.Another possible problem would be a damaged reluctor wheel,cracked or chipped tooth.Well you have something to start with but I will add one more thing on an older Explorer I put an aftermarket rotor on 1 side and it did the same thing and I had to remove it.
 

Last edited by davo; 11-30-04 at 03:51 PM.
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Old 11-30-04, 02:47 PM
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Originally Posted by davo
but I will add one more thing on an older Explorer I put an aftermarket rotor on 1 side and it did the same thing and I had to remove it.
I had the same thing happen on a Ranger although I think the situation is rare.
 
  #6  
Old 11-30-04, 08:44 PM
cheapfurcoat
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I checked both front wheel bearings when I did the front brakes. They are fine. The pulse wheels are actually inside the hub assy. and the sensors are mounted outside with the sensor part probing inside the hole. The rotors are the factory ones and still have plenty of meat on them. I would hate to try the sensor on one side because the whole front brake assy has to be taken apart including the backing plate to get to the sensor. I just may take it to someplace with a diagnostic computer to fix this or at least tell me which sensor to replace.
 
  #7  
Old 12-01-04, 05:41 AM
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I had a similar problem with my anti lock brakes on a Mercury Sable. There was a ring with teeth on it that the anti lock sensor uses. The ring was cracked, so the sensor would think anti lock was required. Not sure if the ranger has the same design, but I had the ring replaced and the brakes worked fine.
 
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