I have a 2004 sierra 1500 with 72000 miles and am experiencing some harsh shifting. It only does it when I am just cruising. If I take off from a stop light at anything more that 1/4 throttle it shifts fine. If I take off slow it shifts very harsh from 1st to 2nd. Also if I dont completely stop at a stop sign before taking off again, its like it hesitates between gears. Anyone got any ideas

 

I should also mention that this truck came with 16 inch rims with 75 seris tires on it. I put 17 inch 75 series tires on it (factory take offs) Would this have any effect on it? Do I have to reflash the ecm for the different tires. When I put the tires side by side there really wasnt much difference.

 

Did you buy it new if not it sounds like a shift kit or a Corvette servo was installed, I could be wrong. You checked youre trans fluid right? most people pay money to get that but I do understand why you might be worried these trns pretty much suck.

 

Another thing to check into is computer programming. I put a diablo tuner on my 00 and it made it shift very hard at partial throttle shifts but at WOT it shifts nice and smooth. If it has been programmed and you have the programmer you can go in and adjust this so that it will shift the way you want at partial and wide open throttle.