04 GMC 4WD - ABS brakes grind

[fathersnsons]

Again I have to reach out to the mechanics on the site.

Our Pickup, has developed a challenge with the brakes in that the ABS, grind everytime we slow down & come to a stop.

Oddly it kicks in right around 9 mph. Other than the crazy noise they seem to be working otherwise.

We do have a trailer brake controller unit installed otherwise its stock.

I appreciate any helpful reply.

[Super Scout]

GM had an issue with this, I dont remember all the details but there might have been a recall as well. The wheel sensors get dirty from too much corrosion in the wheel bearings. Causing the ABS to kick on normally below 9mph.

Here is a link, hope this helps.
http://www.automotiveforums.com/t403797-nhtsa_investigates_gm_abs_problems__.html

[steveg0690]

Yep, sounds like a dirty or failed speed sensor. Chevy has yet to produce an ABS that is any good, I unhooked the ABS in my Blazer a long time ago.

[88wd21]

I agree with the dirty/failed sensor, for some reason I personally see it more common in the RF sensor. You can take e sensors out and attempt cleaning them. Sometimes it works, sometimes it don't.

[DMG]

The hub corrodes under the sensor and pulls the sensor a little bit away from the reluctor ring which causes the ABS to sometimes think a wheel is locked up at low speeds. You have to remove the sensors from the hubs and clean the surface they sit on. Often they are destroyed during removal but they can be bought seperately from the hub through a GM dealer.
The other possibility is that a unit bearing is going bad, check them for play with the truck jacked up.

[brooks294x4]

DMG is exactly right on this one, i work at the dealer and have fixed about 200 trucks by cleaning the hub surface under the ABS sensor. the sensors are prone to break when removing them, be careful and use some pb blaster to wiggle them out, they are $75 a side form the dealer.