Volvo Repair: Overdrive switch, volvo 740, dash lights

Question
My 1989 Volvo 740 will not go into overdrive. It stays in fourth gear. I have been told the overdrive switch is probably bad.  How do you access this switch to change it and how difficult is it?

Answer
         Hello Paul,

                   Often the problem with OD's that stopped working is the OD relay...located within that mass of wiring that lives in the center lower area of your console...behind the ashtray...when you find it...you can test it....with the car in 4th...tap the relay against the shifter...se if OD light on dash...lights or blinks...of so...you need a OD relay.
              OD switches do fail...
                Use a test light...you'll figure it out.

           Good luck

      Bilbo