Speedo reads approx 1/2 of actual speed. At 60 mph speedo reads about 30 mph, if you go faster speedo burys itself. I have changed vss, no help. Scan data reads same as speedo. I have changed ecm and tried 2 different proms, no change. Tire size is 1 size larg...

FIX posted 6/27/2005

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