Volvo Repair: 1987 Volvo 740 GLE wagon with m46 transmission., volvo 740 gle, freeway speeds

Question
Hello,
For some time now, the overdrive on my manual transmission has been
acting up.  It will only engage when the car has been cruising at freeway
speeds after an extended period of time.  The overdrive will not engage when
the car is cold.  

    Once it finally does engage, it goes on and off like it's supposed to.  When
you turn the car off, it will take a while for the overdrive to be able to work
again.  I hear the notorious "click" and see the green number 5 appear, but
only after some time.  Does this sound like a problem with the overdrive
relay, or the solenoid, or both?  Thanks a lot.

Answer
Ian, Most likely its a relay or the o/d relay but I have seen the actual switch on the shifter have an intermittent issue like you are describing.  There also may be an issue with the switch on top of the trans that allows it to go into the 5th gear.  Roger