Help!!! I've tried 3 fuel gauges and none work.How do I check the board or gauge to see if I am getting power to them? Can I get it from some where else? The wiring from the tank seems to be fine as far as I could follow it.Also how do I get a light to the small clock after making my large clock/tach swap?Everything works great but I can't see the thing at night! Thanks

The fuel and temp gauges get power from the small voltage regulator. Its the
transistor looking thing on the back of the dash. It's plugged into a small
socket and the metal tab on it is screwed to the back of the speedo. It's right
next to the temp gauge. You probably dislodged it or maybe you broke one of
the legs on it. This regulator takes the 12v and reduces it to 10v so do not
put 12v to the gauges. The regulator may have gone bad but they don't go bad
often.

The small clock is supposed to have a harness that runs from the back of the
tach. This supplies the clock with power, and lights. If you didn't get a harness with it you can make your own pretty easily. Let me know if you need
to find out what terminal is what on the tach. The schematic is in the Bentley or Haynes books. The terminals I'm referring to are a cluster of three on the
back of the tach. As you already know the one single terminal is for the tach
signal. Rpms are much better than a large timepiece.
Dave 82 242ti 263k mi.

I have changed that little regulator or what ever that thingy is called. The temp gauge works fine, also. The tach works and lights up...it's the little clock that doesn't light.No big deal,though,because the clock on the radio display works. The gas gauge is driving me nuts,though.

"The tach works and lights up...it's the little clock that doesn't light."

You misunderstood. The 3-wire harness between the clock and the tach provide both operating voltage (red wire) and lighting voltage (green wire) to the small clock. The black wire is the ground. If you have the harness connected OK, check the light bulb.


Good Luck,

Bob

:>)

The problem with your gas gauge could be the sender. The one on my 1978 has gone bad; gauge is correct when the tank is totally full and totally empty; the rest of the time (between 1 gal and 14 gal) it's in the middle. Kind of like a stopped clock being right twice a day. This REALLY became a problem when the odometer went out; up till then, we'd been simply refilling the tank every 200 miles. Now we just sort of guess; good thing it's not our primary transportation.

Anyway, I'm almost certain the trouble with my car is the sender. Problem: it's in the fuel tank, and I've been told it's very expensive and hard to find a new one. I got adventerious and tried to pull one off a junkyard car. Was such a nightmare getting into the tank, and I had to cut so many fuel lines/jiggle the fuel pump so much, I decided I'd rather live with the problem than risk blowing myself up trying to do this procedure on my own car (junkyard cars, fortunately, had their tanks trained).

Bottom line for you: don't overlook the sender. My general experience with cars - Volvos and otherwise - is that when a gauge is malfunctioning, the problem is almost always the sender to that gauge. The 1989 fuel gauge sender might be easier to replace than the 1978. I'd look into it.

As for the clock light: I have that same little clock as yours in my 1984. This may sound like a dumb question, but are you sure the light bulb itself isn't burned out?

I'm not even sure that there IS a light in the clock! But I really do need to fix the gauge....I'm driving from Upstate NY to N.H./Maine and back each week.

there is a light in the back of the small clock. very easy to fix. remove the trim around clock, pull clock out(make sure you dont loose the rubber pieces that hold the clock in the dash), and the wire that goes into the round part of the clock on the back should pull out and expose the light(holder) u have to get the light from the dealer. about 2.00. good luck-scott