Volvo Repair: 1990 740 Electrical Mystery, haynes book, temperature guage

Question
Richard,
I have 1990 740 wagon with the 2.3 8V FI engine with auto trans. The car was not driven very much for a couple of years. When it was begun to be driven again on a regular basis, several "gremlins" have appeared. First, the cruise control  has stopped functioning, the speedometer would hang up or freeze, the temperature guage is not working and the display light on the radio doesn't light up. The radio works but no display. The speedometer would begin to work after pounding the dash above the instrument cluster and now seems to be working fine but the other problems persist. My local Volvo service center can't seem to find any answer. The temp sensor was replaced but no better results. I have done some investigating behind te instrument cluster but have not found any loose wires or anything out of the ordinary. I was wondering if there is anything in common, a ground lug or junction that all of these may have in common. My Haynes book doesn't offer anything of significance and the local service center could only offer a long and expensive dash removal to investigate. On several occasions I have observed the display light on the radio working but after a bump or two it goes out again. I have removed the radio but again no loose connections. Just looking for a place to begin looking.

Answer
Tony, the cruise is probably an easy fix.  Check the vacuum bellows for holes, Also check all vacuum lines.  Lastly adjust the cruise switch on the brake pedal.  If that switch isnt adjusted properly, the cruise will not work.  As far as the speedo, Its usually the actual speedo head that goes bad on these. If you already checked all the connections, I would check all the screws on the circuit board for tightness.  Its most likely the head.  Sorry for the bad news.  Throw Mr Haynes in the local file 13.  Roger