I don't like to have my gauge cluster to be too bright, but the aftermarket gauges I have are too dim when hooked up. Unfortunitely the gauges are too bright when I hook them up to the direct 12V supply. I would like to be able to still adjust the gauges with the dimmer but have them brighter than the regular cluster. Is there a way I can make a devise that takes the dimmer voltage but then bumps it up for the gauges?

Basicly I want to run the guages a few volts more that what the dimmer switch has but is still controled by the dimmer.

Does this make any sense?

 

I could think of a few ways to do this, depending on how fancy or simple you want it to be.

I'd say to start by getting an assortment of dash dimmers from the junkyard-----get them from Japanese cars, because the dimmer is separate from the headlight switch. Nissans use ground-controlled dimming, so I'd avoid them-----Toyotas are likely to be simplest.
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Then, the easiest way would be to attach the input of the dimmer to the car's brown parking light wire---found at the switch, at the radio, or in the driver's kick panel. Attach the dimmer's output to your aftermarket gauges, adjust it to the desired brightness, and secure it somewhere up under the dash where you can reach it if readjustment is needed.

Pro: Just a few wires to hook up. Con: You'll have to twiddle with two ***** anytime you want to change things.
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If you want to be really fancy, get to the wiring at the headlight switch and do something like this:

1. Find the dimmer wire from the headlight switch; cut it in half. Hook your aftermarket gaugues AND the Toyota dimmer directly to it. Then, hook the output of the Toyota dimmer to the other side of the wire you cut in half.

Adjustment: Turn on parking lights. Use the Toyota dimmer to adjust the factory gauges to match the aftermarket ones. Bury the Toyota dimmer in the dash and put the car back together.

Pro: You now can control everything easily, with your factory dimmer. Con: You can no longer turn your factory gauges all the way up, unless you take the dash back apart-----but it sounds like that's what you'd want anyway.

 

If you don't like the idea of wiring as Chris suggested in the previous post you may be able to find a different bulb # that is of higher wattage than the bulbs currently fitted into your aftermarket gauges. Check the numbers on them and compare them to ones available at Radio Shack and/or auto parts stores. It is most likely a standard bayonet base with the small bulb on it.

With a bit of experimentation you should be able to find something a bit brighter. Perhaps buy a handful of the same size from a wrecker, you'll be able to try all kinds of different numbers for cheap.

Don't be tempted to try 6-volt bulbs, they'll burn out very easily if someone cranks up your dash lights for even a few seconds!!

Years ago when I worked in the speed parts biz Autometer offered green & amber rubber boots to put over the illumination bulb in the instruments. If your current lights are too bright these would colour & dim them somewhat.

Alternatively, you could wire in one or more diodes between the voltage source and the aftermarket dash lights. Each diode put in series will drop the voltage by about 3/4 of a Volt. This would require insulating the diodes from the underdash metal or chassis, once you had determined how many diodes you need in series you could heat shrink the whole works and stash it under the dash - but of course this setup isn't adjustable either.