1994 Lincoln continental, with no tail lights or running lights.

I have checked the headlight switch, the radio powers up but does not make a sound. On Fuse #4 it blows everytime I turn the headlight switch to the parking lights. All of the the tailightss, marker and license plate bulbs were burnt out and I have since changed them all. Is there is a special relay or something that I need to find or test to see if it is shorted out? When I tested out the wires behind the headlight switch I had continuity to brown white, and red yellow. The digital cluster works fine, except the the fuel indicator and oil pressure, battery and, temp gauges are dim, perhaps these are on a dimmer? Thanks in advance for your help.