Replaced headlight switch and connector. Everything worked for a month and now no dash lights tail lights.

Are you having a repeat of the same connector meltdown issue? is there a moisture in the cab issue ? Following the schematic and testing the circuits at fault may reveal excessive resistance in the connectors between where you have the melt and the load is in each circuit. Hard use, off road use, Even parking brake release jarrrrs the fuse panel and all the connectors. Places where electrical connections experience excessive vibration, jarrrring, moisture present, exposure, or just plain unprotected from the air, makes the dissimilar metals begin to react and create oxidaion and eventual cheese. it HAS been 25 years and beyond for that rig, bud.

There is a motorcraft switch and wire kit that provides extra long wires and increases their gauge diameter. The lil biddy one can be replaced further away or up to the next connection in order to increase its heat carrying ability, but finding resistances caused by loose fit and oxidation will give the most effective use of your time and materials.

Have you checked your fuses. Most times dash and tail lights use the same supply power.

instrument illumination for ford trucks ? aren't they fused by a very small separate fuse that powers that circuit when the switch is pulled out? It is also located in the fuse panel, but is powered by a bridging from the next fuse over, I thought. . It may have just melted again if the cause was not found, and the symptom was treated.