I didn't consider belt slip. I always enjoy your analysis cruzinquick. Do you think belt slip would cause an early shift? Tom's car is shifting at the correct rpm from third to fourth. The early shifts are occurring on the 1-2 and 2-3 shifts. Are the faster climbing revs in the lower gears more prone to belt slippage? Would it empower the traction control to intervene if the belt started slipping badly? I ask because I'm seeing similar data logs as Tom's. I'm thinking of unplugging fuses 17 and 18 as an experiment to see if I can eliminate traction control as the cause.

Oh, I took my car out and leisurely accelerated in manual mode through the 1-2 and 2-3 and the car shifted at redline. So something is causing traction control to take over on the full throttle runs; for both Tom and myself. (I have a Code 3 too) How hot should the belt get? After a run I can't hold the belt, it's too hot. It never occurred to me to hold the stock belt so I don't know if its hot from slipping or if the temperature is normal for the belt on our cars. I don't see any obvious signs of slipping. Just thinking out loud. If we can trouble shoot for Tom it will possibly help others too. (like me!)

Les