inappropriate ABS Activation

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  #1  
Old 10-23-18, 08:04 AM
P
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inappropriate ABS Activation

2000 Chevrolet Suburban K1500

I am experiencing inappropriate ABS activation during slow braking. (4-7 mph) Before this gets too far, I am well aware of the existing issue with Chevrolet trucks and SUVs getting rust under the wheels sensor and causing bad readings leading to ABS activation. I had one front hub replaced in 2010 and the other in 2012.

I bought a new hub and was going to replace the bad side. I asked my tech to use his scanner to identify the bad hub so he plugged it in and we went driving. He expected to see either the front left or right side ABS solenoid activate which would indicate that the wheel speed sensor was bad on that side. Unfortunately, he was seeing all three solenoids activating (left and right front and rear drivetrain). He was totally confused because that is not how it is supposed to activate. It is only supposed activate the solenoid for the sensor that reads slower than the other wheels. They can't all be less than each other! His conclusion is that only because of the improbable readings, it must the the ABS computer. If that is the case , I am pulling the fuse because this vehicle is rusty/crusty and not worth $1000 in parts. Trying a used one is a risk not worth taking because of the labor for getting the old one out.

The one thing that he did see was an occasional lack of response from the front left sensor. You would expect that to trigger the ABS but it didn't.

As stated earlier, I already bought a replacement hub (with the sensor included). I am inclined to try replacing the left side hub (or at least cleaning the rust from the existing sensor mounting) to see if that makes a difference. Because I can't explain the ABS activation, I am hesitant to go that route.

Any ideas or suggestions?

- Peter
 
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  #2  
Old 10-23-18, 11:32 AM
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Does that rig have replaceable Reluctor Rings (aka ABS Tone Rings) ?

Sometimes, under rusty conditions, these rings crack and spread their teeth enough to throw off the ability of the ABS Computer to calculate speed.

I had this problem on my 2002 Volvo up here in Vermont, and took pictures of a rusted and spread Reluctor Ring that I replaced:

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And another with a close-up of the crack:

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You can check your Rings for such cracks by removing the Sensor and peering down the hole as you slowly rotate the wheel.

I had to go to the United Kingdom to buy replacement Rings . . . . here in the US they want to replace the entire axle while the Rings are less than $25 apiece !
 

Last edited by Vermont; 10-23-18 at 11:51 AM. Reason: Repositioned images
  #3  
Old 10-23-18, 11:51 AM
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No. The tone ring is part of the hub and the sensor mounts into the hub and is sealed. The only exposed surface is the outer face of the hub where the sensor mounts. I could replace the sensor only but not the ring.

- Peter
 
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