about a week ago,I was out on the highway and noticed when I got back into town that the transmission on my 00 sierra (2500 4x4 with a 6.0 L) was shifting really harsh through all gears, but still went from drive to reverse normally. Feels just like a shift kit in the transmission and will acftually chirp the tires on the 1-2, 2-3 shift. It even shifts hard into OD. Trans temp on the gauge was just off the low side pin (40 degrees??). After it cooled down, it was shifting smooth as butter again for a couple of days (city driving only), but as soon as I took it out on the highway (5 miles, then turned around to come back) the shifting was harsh again. let the truck sit for a couple of hours and it was fine again. Fluid level seems to be up and in good condition. Any thoughts what could be the problem from the gurus out there?????

 

check er for codes...i think the pressure reg or motor is letting too much line pressure occur

 

thanks argon, I'll have to check that next time I ahve a spare moment. I'll keep everyone posted.

 

OK, so to revive an old post........I FINALLY got to hook a scan tool up to the truck and got codes for transmission component slipping, TCC solenoid stuck, and an o2 sensor code. The o2 sensor code is a no-brainer. To deal with the transmission, I cleared the codes and went for a drive and the slippage code came back. Watching data stream shows a significant amount of slip in the torque convertor. With the TCC solenoid engaged, there is no noticeable drop in rpm. the solenoid data stream will then dis-engage, which will then give me the harsh shifting. Any thoughts??