[350]

Anybody else have their ABS randomly kick on at low speeds, almost stopped? The last few days it was wet so I was thinking maybe upgrading my brakes would stop it a little quicker than the ABS made it think it should, but I got it today when it's complately dry out. I've also been having Stabilitrak activate basically every time I drive the truck so I turn it off first thing, so I'm guessing ST isn't causing it, soemthing is up with ABS that is causing this? Any ideas?

Thanks

 

[Bill Johnson]

Front Wheel Speed Sensor the most likely cause....
If you can find someone with a Tech2, or scanner that can monitor ABS/Speed sensor data, you'll most likely see the left or right sensor drop to 3MPH before to whichever "Good" sensor drops...(Trailblazers start at 3MPH, not 0MPH)...For instance, (Bad LF sensor), all the sensors are reading 10MPH, you slow down, all sensors are dropping like they should, then when all sensors hit 7MPH, the LF drops to 3MPH....EBCM is noticing a speed difference, thinks there's a wheel slipping, therefore engaging the ABS....

 

[350]

Tech II pulled a code for front right wheel speed sensor, didn't read the speeds or anything. I figured the code was old cause I swapped the hub last year and I had had service stabilitrak before, how much of a PITA would be be to swap sensors on the hubs? I could move my old one back to see if it goes away because I didn't have issues with the ABS back then.

 

[350]

The code I had was C0040 Right front wheel speed sensor circuit, swapped in another wheel speed sensor yesterday on front right and no difference, still kicking in at low speed. Any input?

 

[truckshop]

Any slack in the bearing? A bad hub can do this also.

 

[350]

How would I check for that? The hub is about a year old.

 

[truckshop]

Jack up the front and feel for any movement in the hub.

 

[SLOWHITE]

Maybe the wheel speed sensor isn't installed exactly correct. For example, full size chevy trucks 99-07 style had a problem with rust forming on the wheel speed mounting surface of the hub. This small amount of rust would lift the sensor just enough to throw off the sensor reading and would result in the problem your having. The GM fix was to remove the sensor, clean off the rust and paint it with an anti rust paint, then reinstall. So maybe your sensor isn't in the exact spot since just small amt of rust could throw off the reading... Not trying to be a dick, just a possibility.

 

[Bill Johnson]

How would I check for that? The hub is about a year old.

AfterMarket, or GM hub?

We've seen alot of people having problems after putting in a cheapo hub in, they end up in my dealership anyways, then have to go through the hassle of getting reimbursed....

 

[Red Rocket]

Don't ever deal with cheap Hub's.. Bill Johnson pretty well covered that one well enough.

It's with out a doubt a hub issue. Rust or no Rust in the sensor you might as well just replace it IMO.. You can take your time clean up the sensor install it then a month later deal with the same issue. If a car or truck came into the shop for this issue and the customer wanted to patch it with cleaning the sensor and putting it back. They would tend to be back for a new hub within a month. I feel as that removing and cleaning it is just a patch 90% of the time.

 

[ForceFed]

Are you tuned or stock?
Tunes can screw this up too.

 

[350]

Aftermarket hub, I swapped in the OEM sensor that worked fine from my old hub, no difference. I'm tuned too, but the hub and the tune were both done about a year ago, maybe 5-6k miles since both would have been done. So you guys are thinking it's something internal in the hub and not the sensor itself?

 

[Bill Johnson]

Changing sensors never works, the tolerances are so different from hub to hub, sensor to sensor, I've changed them on customer cars, and sometimes it's worse....I really dont think a tune would change anything, since you didnt tune the EBCM...the only thing I could suggest, is to make sure the wiring harness hasn't got pinched, and the connectors to the EBCM have no oxidation....probably a good Idea just to unplug them and put die-electric grease on them anyways...If all is good, then bite the bullet and get the right hub from a dealer....They're expensive, but you won't have to worry about what is right or wrong in the future...

 

[mrinken]

I have the exact same problem as the OP except my Stabilitrac also activates randomly at say 30 mph. New no hubs recently. How hard is the hub install? Maybe I could get one from two-tons instead of getting raped at the dealer?

 

[350]

My stabilitrak is acting up too, but I have a dlifferent code it was my steering angle sensor. Honestly my other aftermarket hub is fine and they're so freaking cheap I'm probably gonna get another one. If you can change your rotors you can do the hub, the hardest part is finding a 36MM deep socket for the axle nut.

 

[gn2beatu]

If you have a depth gauge you could measure the distance on the right hub vs the left hub. If it is off like a 1/16th you could just take and remove a small amount of metal where the surface of sensor is mounted. Hey its a free shot? ;-) Did you clean the other sensor on the other side so they would match? Allot of debris build up on the magnets. Did you could remonitor the speeds with the Tech2 to see whats going on after you swapped.