Dim lights in dash

Find "the little" instrument fuse which is at one end of your fuse panel.

The way this works is, the dimmer gets power from the tail /park fuse, so make sure the tail lamps are bright, IE getting good voltage.

Then power goes through the dimmer, TO the inst. fuse, and then off to all the lamps

So check voltage at both ends of the fuse. If you can twist the dimmer far left and get nearly battery voltage, the dimmer is OK.

The dimmer is just a simple exposed rheostat, with a moving contact, so it's subject to damage, wear, and corrosion.