Headlights on makes the dasboard go dark

It wouldn't hurt to clean all the grounds you can find, particularly the ones connecting to the headlight housings.

I would have the battery and alternator checked, just to be safe. AutoZone will do it for free if you don't have the tools.

Dave

There is an "instrument brightness control switch"

Its not a design feature is it? My missus has got a FIAT that does the same thing - turn the ignition on and all the panels and illuminated switches light up - turn on the headlights and said panels and illuminated switches dim a bit. I think the logic behind it it that if its dark enough to need lights you don't want your dashboard glaring you in the face and blinding your night vision.

Nige

That was it! Thanks.