Are all 4 hubs the same?

[regalfriend]

I have a 97.5 GS. 130,000 miles. Recently my ABS/Trac off/SES lights came on. They dont come on until i start moving. I had the front left hub replaced a year ago. AC Delco. My brakes in the front are low, and need to be done. Not sure if related. I know the only way to properly diagnose is to scan w/ tech 1 or 2. A few questions. The abs/ traction and low tire light works off the hubs? If any one of my wheels slip, including rear does the trac enable, or the ABS?. Does trac just work if only the front wheels slip? I also have the low tire indicator. If 1 of the hubs go bad, why doesnt the low tire light come on? .....If i put the car on 4 jack stands, put the car in gear and let the front tires spin, will this set off the trac or ABS? If the problem is ABS related and not hub related will OBD tell me? I know there are alot of questions here, but am trying to avoid the dealer....in a BIG way.

[BNaylor]

From what I know the front hubs L/R are the same. The rear L/R match and appear to be similar to the front but have different GM part numbers than the front.

The low tire indicator system uses the same ABS wheel sensor as ABS and traction control but the calibration and tolerance is different.

You can try jacking up all four wheels but you may get a traction control indication or abnormal ABS. Low tire may even come on because the rear wheels will not be spinning.

In normal driving conditions, the only time I get traction control is when the front tires spin.

Have you performed an inspection on all of the wiring going to each wheel sensor to include the electrical connector? With a digital mulitmeter you may be able to detect a flaky wheel sensor by ohming out. Just go across the sensor contacts on the hub side. Ballpark reading will be around 1K ohms resistance. The one with the bad reading will be the bad hub. This doesn't always work but doesn't cost that much.