Does anyone know how to wire in a voltmeter into a '83 240? I have all the parts, just do not know how to wire it in.

Thanks to all for all your help!
Cormac

Here's what I did:

Run a positive wire to a fuse with keyed 12V (I used #13 on my '88; yours may or may not be the same). Connect that wire to the positive side of the voltmeter. Wire the ground (inverted T?) to a valid ground connection (you can bridge with the ground from another gauge). All that's left then is the wire for the illumination, which you can also bridge to the illumination wire to another gauge (on the positive side). The negative side of the illumination can ground in tandem with the main ground from the gauge.

Hope this helps. Others may have better details.

--
Guid ('88 244DL 216k, '92 745 165k)

Guid's directions will work fine- I did it a little differently in my 83: I wired the voltmeter to the pos and neg wires going to the cigar lighter in the center console. This is "hot" in the ACC or RUN positions of the ignition. Connect the lighting terminal to the small brown wires that go to other lights (gauges, heater control panel, etc) and you will get the dimming function. To mount my voltmeter (and oil pressure) I got two of those square panels with the recessed opening that are used on the GL models to surround the small clock to the right of the instrument cluster. The gauges mount in the holes in the dash behind these panels - I just wrapped the gauge bodies with vinyl electrical tape until they were a nice press fit. The panels then snap into place and the recesses snug up to the gauge bezels for a factory stock look. And I still have all the space in my upper cubbyhole. VDO "Cockpit" series gauges are a close match for the std. Volvo dash gauges.

Takaisin Pääsivulle in Finland has kindly put on his web site the Volvo factory instructions for installation of the voltmeter accessory. The instructions with pictures and part numbers break the job down into simple steps, like Lego construction and are highly recommended.
http://kotisivu.mtv3.fi/karu244/jannite.html