Transmission Blues.....2004 z71..shifting into 2nd only after high revs

Good morning.....
I am new to the forum , but not new to Avalanche....
My baby wont shift into 2nd unless it revs high then i let off gas and it will shift..I think its shifting into 3rd..idk
So , there was a code for solenoid A being stuck..So I ordered and installed full solenoid kit with wiring harness...
I changed them all.. I refilled with synthetic fluid also...
Problem still there.. I'vr brrn doing more research and found that maybe T.P.S. is problem..Any feed back?
Oh..I had my meter hoked up when driving , so V.S.S. is working..And I replaced gauge cluster..
Please send any feedback or ides..
Thanks y'all

My 2004 EXT failed in the same manner you described.

Mine burned out at 125K.

New solenoids did nothing.

Clutch packs were worn out.

Time for a transmission rebuild.

And don't forget to have a new torque converter installed, as well.

Thanks..
Not what i wanted to hear , but figured as much..
It does have 250k on it

You are ahead of the curve with 250K on it.

Just get a rebuild at a shop you trust and you should be good to go for quite a bit longer.

I find it hard to believe that I now have almost 85K on this rebuild.

Nothing fancy or exotic put in at my rebuild and I did a pan drop and fluid/filter change at the 50K mark after the rebuild.

Everything seems to be holding up just fine.

But, then again, the last failure did not give any indication that failure was imminent.

It just up and failed one day.

I'm of the same mind as EXT4ME - you likely need a tranny rebuild.  I doubt that a throttle position switch would generate that error as it tells me the tranny is sending the command to shift but the shift isn't occurring - if there was a problem with the throttle position switch it would be preventing the computer from attempting the shift. 

250K miles out of one of these transmissions in these heavy vehicles is pretty good - mine started giving me problems around 200K.  You've probably got a seal that has failed or a stuck valve.