Ok, I have a 2003 XC90 T6- I know great transmission! Anyway, it has 82,000 miles, the transmission was of course out, had it dropped and the clutch packs replaced and anything else in the master rebuild kit. Put it all together and is was fine for a few weeks. Now I have a “Service Transmission” message coming up and it won’t get out of third gear. After I turn off the engine then later restart it, the message is gone and it’s fine for a little while then does it again. Does anyone have any ideas?

 

I'd look for a loose ground wire or cracked connector to the transmission. Also check/clean connectors at the TCU.