Chip did you ever find out anything on this? I ask because I was convinced based on some info I found online that I probably needed to replace the sensor in my 2004 Tahoe. It seems to wander on the highway at higher speeds, like you are driving in a stiff wind but there is no significant wind. So I checked with local GM parts dept and they identified the steering position sensor on their diagrams and ordered the part for me. It was $153. I found online diagrams and directions on replacing it. Then the odd part, I got under the dash to look at the sensor and determine how difficult the job was going to be only to find that my Tahoe didn't have a sensor. The steering shaft has the bearing and holder for the sensor but there is no sensor there and I can't locate any electrical connection where one would plug in. The dealer parts guy swears there is supposed to be one on these vehicles. I plan to talk to one of the service techs in the morning to see what they say.
Anyone else had this issue?