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I have 1999 GMC Sierra. There are no check engine lights on. The engine runs well and 4 wheel drive works well. When I brake when going slow (like 10MPH or less) sometimes the ABS engages causing noise and difficulty braking. It is just the left-front wheel that is making the noise. This happens around 30% of the time when I stopping at the end of my dirt road or pulling up to my house. It doesn't happen when I'm on the road.

Can you give me some suggestions on troubleshooting the cause of this?

Thank you.

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GMC and Chevy trucks have a known problem with their front wheel bearings.

The ABS sensor slides into the wheel bearing and is bolted on from the outside. This type of sensor is very sensitive to the gap between the sensor and the reluctor wheel inside the wheel bearing.

Over time rust builds up between the bearing and sensor and will pull the sensor slightly out of the bearing increasing that gap. With the gap wider the sensor will drop out at lower speeds making the ABS think the wheel locked up.

There are two fixes. Replace the bearing. This gets you a nice clean bearing surface and new sensor. The second is remove the sensor (very difficult without breaking it), clean the surface with sand paper (block the empty hole with a rag or something. Then put the sensor back in. Put a little oil or grease underneath the sensor before putting it in to help with the rust.

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  • Thank you for the details. Some people in person had commented that I probably need new wheel bearings on that wheel but nobody could tell me why. This is very helpful.
    – mrtidy
    Apr 18, 2017 at 18:25
  • @mrtidy not a problem.
    – vini_i
    Apr 19, 2017 at 0:09
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    Following up on this: I bought a wheel bearing hub assembly and replaced the old one. The old hub assembly was difficult to get off but I did get it off and then new one on. I've driven around town quite a bit now since the replacement and no more troubles. Thanks again.
    – mrtidy
    May 15, 2017 at 14:17

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