I stumbled accross a fix last weekend for my dim dash board lights.
A couple of weeks ago I installed some LED bulbs I bought off of ebay: Item title: 2 x T10 Super White 6-Led Light Bulb
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These offered some improvement, but still was not happy with the brightness.
The following week I noticed my charging system was not charging (this was a new problem and did not have anything to do with the dimness of the dash lights), so I had the Alternator tested at Autozone, but it was fine. I had a new Motorcraft voltage regulator and starter solonoid (just did the solonoid for looks really) so I begain the installation. In the process I took my Dremel tool with a wirebrush attachment and cleaned the mounting holes and screws for the regulator and solonoid. I cleaned all the ends of the wires that connected to both the regulator and solonoid, as well as the battery terminal connectors at the solonoid and where it grounds to the regulator. I also cleaned each connector at the back of the alternator while I was at it. It took some time and patience, but when all was reassembled I tested the charging system with a voltmeter and I was getting almost 14 volts at idle.
That night I started to take the car out for a spin and when I turned on the lights I could not believe how bright the dash lights were, including the radio, clock, lighter, wiper knob light, headlight knob light, and auto shift light. I'm not sure, but the wire that goes from the solonoid accross the shock tower mount support and into the firewall may be the clue. It's round connector was pretty corroded.
Here are some before and after pics of the solonoid and regulator and the associated wires. I took thses pics as a reference for reassembly. Try cleaning up all the connectors, holes in the fender, and screws. Remember to disconnect the battery first. Apparently one or all of these wires was the problem.
In this pic I outlined the area in red for the wire I believe goes through the firewall. Not sure what the rectangular thing is called that the wire connects to on the solonoid, but I spent a lot of time cleaning all the contact points on it. It may be the key to the brighter lights.