Transmission issue 2500 HD

[Sba_95]

Hello gm trucks members ! 

I need your kind advice about my truck issue. I have a 2018 chevy silverado 2500 HD with the vortec gas engine and the 6 speed transmission. My truck was shifting vrey smooth in the first 1000 miles. Then , the transmission started to shift hard in the 2nd gear, specially when the rpm above 3500. In low rpm's the truck shifts smoothly. I took it to the dealer to check the transmission programing , they said that it has the latest program and everything is normal ! 

I like my truck but this hard shifting is very annoying. 

Many thanks for reading my topic and waiting for your advice. 

Best regards , 

[Sba_95]

I forgot to mention that my truck mileage is 9000 miles only 

[1SLOW1500]

Need a adaptive relearn and the scan and drive. I would opt for a full pan drop fluid change. I know sounds like over kill. But Gm will just kick can down the road. And what is a few hundred compared to cost and time later.
Oh also try to take. Notes when this happens. Is it a downshift if so 1 or 2, afm/DOD, after hard acceleration, engine coolant temp? Then try other shift patterns like tow.

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