On my '78 I noticed last night the lights illuminating the console guages were not working (all new bulbs as of last year). The speedometer and tach were lit properly. The last time I drove the car at night (about a month ago), the gauges were properly lit.

I checked the fuse and it's OK. I'm guessing I have a bad printed circuit behind the gauges. Before I take it apart or order a new printed circuit, does anyone here have any different ideas what the problem might be?

Try sliding the 20 amp fuse in and out a few times on the fuse block. Try another fuse, possible. I had the PC piece out, and cleaned up the copper runs. Also, the receptacles holding the lights in get a little corroded, and you just have to clean the little prongs up that twist into the pc board. I call it a board, but flexible plastic with the pc on it. Check the rheostat on the headlight switch.

I'll check the connections on the printed circuit. I can't see it being a problem with the headlight switch and rheostat as it works fine for the speedometer and tach illumination.

I used a test light and current is definitely passing through the fuse OK. All I can guess is either a bad connection at the printed circuit or a bad pc altogether.

Thanks and any other ideas are gladly accepted as well.

The switch and fuse are good, or the speedo would not light. The problem is a common connection or ground from the gauges. This could be a connection where the harness plugs into the circuit board. Not uncommon. Usually a cleaning takes care of it. Sometimes the pc will crack and lose contact. You can run a jumper wire around the plug to a location on the pc that is common to all gauge lights. The power and ground can contact anywhere. This saves the cost of a new pc. It the problem was elsewhere on the pc, some of the lights would work.
If you don't have power and ground at the pc plug, check the harness connections.

The grey wire is the light feed, black is ground.

Thanks Ken...it will be a day or so before I can make the checks you suggest, but it certainly sounds logical. A bad or dirty connector makes more sense than a bad pc, though that's certainly possible.

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