I want to recommend www.cheapabs.com for being able to finally solve my ABS/Trac E-brake light problem. Like most high mileage Grand Prix the 3 lights came on, went to Autozone and it coded as a right rear abs traction sensor. Without thinking too hard I ordered the part from rockauto. Being impatient I just swapped out the parts without ohm-ing each sensor to assure a faulty unit. My luck the fault was not the abs sensor. I then replaced the rear abs harness, that is my impatience again getting the better of me. Forgive me as I normally drive a '91 Nissan with no ABS or electric anything.
After much searching I found Matt from cheap abs sent in my abs unit, very easy to do. A couple days later it was back and no more lights. So be warned about chasing electrical gremlins certainly with the abs sensors. Make sure to actually use your voltmeter and correctly identify the fault. Pontiac in their infinite wisdom used ultrasonication (using high frequency sound) to join electrical contacts or points in their ABS units. Cheaper, faster, and supposedly easier than soldering. I would also not recommend trying to fix it yourself unless you're an electrical engineer with experience doing that sort of work. $110 fixed and shipped to me, no more problems whatsoever.
