Volvo Repair: 1999 Volvo S80T transmission fault code, gm transmissions, volvo dealer

Question
I have a check engine light and fault code that says transmission service urgent.  The specific code indicates a sticking solenoid.  There doesn't seem to be anything wrong with the transmission.  It shifts very smoothly; however after driving 10 minutes or so it goes into limp home mode and will only run in 3rd gear.  The Volvo dealer says I need to install a new transmission to fix.  I think the only problem is the transmission sensor is sending an incorrect fault to the computer causing the activation of limp home mode.  Is there any way to disable the limp home mode so I can continue to drive this car without performing an unnecessary and expensive transmission replacement?

Answer
Gene, sorry these GM transmissions are notorious fot this issue.  It will fail eventually.  Ive seen these cars New on the showrom floor with 10 miles and we had to replace the transmission.  The dealer is right and no there is no way to disable the limp mode.  Its all computer controlled.  ROger