I hope some one can help me. My problem is I have a really hard shift from 1 to 2 at mid rpm shifts fine at high an low rpm an lags an shifts rough from 3 to 4. I have replaced the TOS an vss fluid is fine not burnt. I'm stumped thank you for any help

 

I have an '00 blazer that does the exact same thing. I've replaced the power control module, (PCM), the tps sensor and had the tranny flushed with new filter. Also, When the tranny is in 2nd gear coasting and I hit the gas, the engine revs for half second and then catches gear and goes, feels like to much backlash in rear end but all other gears do not have the problem.

Before I bought my blazer I heard of 4l60e tranny problems, looks like they came true for me, what a crap tranny.

 

Did you have the pcm programed to your vin? That could be some of your problem.

 

I had a Chevy stealership put the PCM in so I'm assuming they programed it?

 

Does the hard shift occur when the transmission is cold, or only after its warmed up (driven for 20-30 minutes)? Have you checked for diagnostic codes? If you have code P1870 it could be the Valve Body Control in the transmission. The older 4L60E had a problem with worn TCC isolator and/or regulator valves, which would cause a hard 1-2 shift once the transmission is warmed up.

 

For me the hard shifts are worse when it's cold and better warmed up. I have had two different places read for errors and none found.

 

I gets worse when its hot after about 45 min or so. An it acts like the convert don't want to stay lock in 4th it has never given me a code or anything. That's y I'm stumped.

 

I have the exact same problem as well. At light throttle it shifts firm but fine.
Hard throttle, fine. Mid Throttle, Hard "shift kit" like feel. I replaced valve body, separator plate, accumulator pistons, fluid/filter, TPS also and it was like i've done nothing at all.Still shifts the same.I believe it may be engine related like a sensor reading off or the cat maybe.
Please update this thread if you find something.

 

If you changed your own fluid it's possiable the A or B solinoid was damaged during installation. (High to Low or Low to High) cant remember which one's which.

As a reminder, all hydraulic systems have to be bled of air. The owners manual actualy tells you to work the gears and reapply fluid in increments while in parks.

 

Maybe it's time to pull the valve body and inspect to see if valves are moving as they should. The smallest debris in the valve body can hang you up worse than you can think. Be sure to have separator plate gaskets ready to replace if you do, and keep a pan beneath when you pull the VB out. That's to catch any check ***** in case they fall out.