I always thought it used the ABS sensors to tell individual wheel speed for both systems, not sure if they do thou.

 

Could be! I'm not exactly sure how it works except that it's a senor and computer control of some sort.

 

It does it on all three vehicles with or without traction control on. On my silverado, traction control cannot be turned on or off. I don't even know if it has traction control except for a limited slip rear end. But the other two, ssr and tahoe does it with it off. A local auto mechanic has told me it could be a problem with the Crank sensor. He says it could be reading wrong and making the timing retard.