Blowing #4 Fuse/ No Tail lights, Cluster, Parking Lights, License Plate light

MV8 said
Don't use fuses to determine if a circuit is good. Use the "ohms" setting on a cheap, digital volt meter. Most have a beeper setting when the leads are touched together. Clip one lead to the fuse socket side that goes to the lights, and the other lead to a good ground. Keep unplugging until it stops beeping to help you find where the problem is.

Actually this does not always / often work very well, because there is often something else on the circuit that you forgot about, some other accessory, or something the owner or previous owner "hacked" like a stereo and is now shorted. A bettery way is to "rig" a tail/ stop socket (1157) you want a bulb with some current draw, and in this case put alligater jumpers up into the fuse clips and to the stop light bulb. A heavy draw/ short will light the bulb. You can go around shaking/ testing/ disconnecting stuff to test.

For really bad shorts you can do the same thing with a stop light bulb or a headlamp which still works---put the lamp in series with the battery ground.

OP did you look it up--- what all does that fuse supply? I'll assure you it does NOT supply the dimmer because the headlamps get direct power from the ammeter circuit. the light switch has TWO power sources.

One HUGE flag, for me, is that fuse no4 also operates the LIGHTER

Could also be a short in the cluster lighting dimmer circuit, HOW THAT works. Fuse 4 feeds power to B2 on the light switch, which powers tail/ park/ and the dimmer control for the cluster lamps. After power goes through the dash dimmer control, it LEAVES the HL switch on TAN and goes down TO the INST fuse, normally on the end of the panel.Through that fuse and out to all dimmer controlled dash lighting on ORANGE lighting. So if the INST fuse is too large, it may not blow, or the short may be in the dimmer control or that TAN wire