stabilatrac or ABS?

[sunrisor]

I did a search and couldn't find anything similar, so...
'08 Envoy Denali with 150k miles.

Traction control system comes on (light on dash, limited throttle) only when cold. Lasts only a few seconds, then returns to normal operation. Doesn't happen any other time. This system seems to operate normally, except there is no reason it to come on in the first place.
When stopped at a light, ABS will pulse the pedal (rather unnerving since the vehicle will lurch forward). This happens completely at random. Steering could be straight, or not straight.

Front hubs seem ok (quiet), rotors and pads were replaced last summer.

There is no service light on. I haven't checked for stored codes yet. This seems to push me toward a wheel speed sensor, but not really sure. I read a few other threads that might make me want to check the steering position sensor.

any ideas here would be greatly appreciated.

 

[freddyboy61]

It is possible that this being caused by a build-up of rust/corrosion under the mounting plate that holds the front wheel speed sensor. This build-up raises the sensor out of the hub slightly and reduces the sensor signal amplitude. It could also be a week sensor, but try cleaning under the mount first.

 

[Mooseman]

So traction control is activating without any need for it? Is the ABS activating when just coming to a stop? That's usually a sign that a front hub is on its way out or the sensor/tone ring inside is wonky. Usual fix is to find the faulty hub and replace it. First I've heard of it setting off traction control. You can turn it off though until you can figure it out.