early abs activation?

[givmiabrke]

check the inside of the cv drive shaft for missing teeth sensor can't read it when going slow ... had this happen ...drove me nuts chasing it down replaced bearings ,sensors and other stuff chasing it

[Hook'em_Horns!]

Originally Posted by Apoleian

kinda weird if there is a prob with the sensor that the light doesn't come on

The light displayed only means that the system is inactive/disabled. It won't display during activation (pulsating pedal) Check/clean the sensor.

Check for movement indicative of the hub needing replacement. This play will also cause false inputs and activate the ABS.

[TORCH]

yes check your hubs first, but there is a recall of sorts for this issue. What others have said is true, the hub builds up rust under the plastic sensor. This causes the sensor to be pushed out of the hole its in, ever so slightly, just enough to cause the sensor to miss at low speeds, contact a different dealer and ask them if your truck is covered for the low speed ABS activation recall. My 2001 gasser had the very same issue. GM will do one of two things: they will remove and clean the sensor and hub hole or if the sensor is rusted so bad that they can not remove it they are to replace the entire hub. I was told that this is a lifetime recall. they voided mine after they found out I had replace the hubs with not GM factory parts.

"I'm sorry Sir but due to the fact that you have replaced the hubs with non gm parts you have voided the recall. Is there anything else I can do for you today?" quote from GM service themselves!!!

I ended up doing it myself, took the sensor out, cleaned all the rust off then with some fine sand paper, then cleaned the mounting surface on the hub real good with a grinder!!! LOL never had another issue with them again.

[Fastmax 58]

Had a 2001 2500hd gasser that did the same thing and i had rust build up on the knuckle between the abs sensor and the knuckle. Clena the rust up and reinstalled the sensor and it fix it.

[Apoleian]

Thats exactly what I did fastmax. Yah, the sensor is held onto the hub by a single screw, and a rust scale builds up under the plastic sensor housing. Make sure you have bolts to pull rotor as they were very hard to get off from all the rust. gently twist the sensor out with pliers and plug hole before scraping off rust. Reinstall and your set. Its amazing that a little bit of rust causes such a problem. Anyway fixed now, thanks for all your help everyone.

[jasonharville]

Hey guys, I'm having this same problem on my 2001 HD. Just to clarify, is this sensor on all wheels or only front/back?

[Apoleian]

The sensor is on all the wheels. But 99% of the time its the front that will give you problems. Make sure you have some strong tools and a couple of long bolts for pulling your rotor off.