Transmission slip 1-2 and 2-3

[Merc1973]

I noticed on my newly purchased Yukon that when the trans is cold, it shifts fine, but a little slower than my other vehicles. When warmed up to operating temps, the 1-2 shift is slow (Flaire?), but no slip, and 2-3 slips with a 500 RPM increase no matter what acceleration. I'm afraid to do WOT at that shift. It has 215k on original transmission, I only paid $2500!!! So A new tranny will not be a surprise. I will update the color/smell of the trans fluid after work as I have not yet checked. Whats my next step. The previous owner was good about maintenance, based on his records he provided. He did tow a large sailboat previously. I'm still waiting for him to mail the rest of his records. What is next?

 

[Merc1973]

Update: Trans fluid look brand new, smells fine. The level is within normal range.

 

[drakon543]

200+k and it was used as a regular/semi regular tow vehicle the transmission is worn out. Have it rebuilt or replaced your call on that.

 

[drakon543]

If you want to try and milk it out a bit longer until you have the work done you can try doing another pan drop to drain the fluid out. If its clean you probably dont need another filter but also your call there. When your ready to add fluid back into it use a container of lucas transmission fix. IF it helps its no better than a cheap bandaid. Continue being easy on it and save up for the transmission work.

 

[Merc1973]

Thanks, i think youre right. I will draw the life out as long as possible and keep babying it. Soon I will be buying a rebuilt RockAuto tranny, Transmission Authority. $1600 shipped and getting $350 core back aint bad at all.

Probably do this on jackstands in the driveway. Does the TCM have to go through adaptive learning for the new one? If so can this be done without $600 software?

 

[drakon543]

That im not sure about.

 

[retiredsparky]

Replacing the transmission will not usually involve a relearn. As long as the battery is disconnected when doing the work(a good safety practice), the TCM does not even know that the tranny is changed out.

 

[berti155]

Hey all! I'm new to this forum, actually signed up after researching the above problem. I have very limited experience with GM transmissions (worked mainly on European cars; grew up in Austria). I have the same issue with the slippage from 2nd to 3rd. It only does it when shifting up but 4th to 3rd is fine. It has become much worse. The transmission is in a '05 yukon denali with 135k miles on it. No trailer use. Once the clutch is closed there is no slip even at WOT. In a different forum I read about the same issue. They installed a rebuilt transmission but that didn't fix the problem. There was no solution. I'd hate to spend the money on rebuilding it and then still having the problem. Does anyone have any ideas? Thanks for your help!

 

[SnowDrifter]

Any chance your valve body has an internal leak causing your shift flare? --- not building pressure fast enough?

Does it hold once it's in gear or does it slip under load?

 

[berti155]

The valve body was my first thought too. It could be a sticky valve or similar. It only does it shifting up from 2nd to 3rd. Once in gear it does not slip. Pulled my friend's trailer the other day and no slippage uphill in 3rd. Can floor it and it still won't slip. I thought about going thru a rebuild but what got me concerned was the other thread I was talking about above. They had the same issue and a new transmission did not fix it. They were suspecting something electrical.