Volvo Repair: Unknown Module Failure on 1999 S80, volvo dealer, oil light

Question
I now know that a 1999 S80 is the worst Volvo to buy, but even my Volvo dealer won't accept them as a trade in so what can I do.  My Volvo is generating "Brake Service Pull Over ASAP" messages with the Brake, ABS and oil light on, the instruments (speedometer, rpm, water) guages fail to work, and changing gears (Park to Drive) fails to register in the instrument panel and the car goes into limp mode.  Or the Transmission service message comes on and the gear shifts register, but the car goes into limp mode.  Once my mechanic reads the codes and clears them the car runs fine until the fifth time I turn it off and turn it on again.  The dealer has done a complete software upgrade, replaced numerous relays, the gear shift module, the ABS module (the ETM module was replace before I bought the car) and has recommended a full diagnostic for $600 to $1,000 and then it may be a wire or it may be a module, but they can't really tell which module and they may have to keep replacing them until the figure out the right one.  Next suggested module is the central electric module.  Is there anyway to just turn off limp mode because the car runs great until something triggers the service messages?

Answer
Robin, Unfortunately no.  The only thing that may help for a short time is to disconnect the battery for 15 minutes but after the car gets going again, the modules will start reading again and the problem will come back. It may be a defective ABS module that they put in.  It has happened before.  i would take your loses and go to a different dealer or just sell the stupid thing as is and buy a real Volvo.  If people would read my columns, all the S80's would mysteriously be found at the bottom of the ocean.  Its a hateful car.  At least the newer ones are a lot better than the 99-00 years.  Roger