2004 GMC ENVOY XUV User Comment / Complaint

I purchased a new 2004 envoy xuv from rally gmc in palmdale, ca (purchased in january 2004). at about 74000 miles (2000 miles after extended warranty expired), the speedometer started registering 45mph, regardless of what speed i was actually going. in addition, it now jumps from speed to speed in 5mph increments. i discovered this while driving from la to dallas on the interstate at freeway speeds in early december 2006. i originally thought it was because it was cold outside, and a sensor had ice on it. but after it warmed up and i found myself going about 80-90mph, while the speedometer registered 45mph, i realized the speedo had failed. i pulled the icu fuse and the speedometer reset and started acting ok for the rest of the trip. it faulted again about a week later and has never worked right since. rally chevrolet/gmc in palmdale ca quoted me a price of $600.00 plus to fix it, plus an indefinite time in the shop.