Here is how dash lights work. The headlight switch has TWO power sources. B1, which is UNfused, and comes direct from the ammeter circuit, feeds only the headlights.
B2, which comes from a fuse in the panel, feeds, power to operate park/ tail, and dash lamps
The dash dimmer control -- (wiggle and twist the headlight switch knob to clean the rheostat and make sure it is twisted toward the left, CCW) --it receives power inside the HL switch from the same B2 source. This means the tail/ park lights MUST be working before the dash lamps can work
The dimmer controlled power is sent out on tan wire DOWN TO the fuse panel where it goes through the INST fuse. Then fed out to all dimmer controlled lamps on ORANGE wire.
I would start by checking tail park lamps, working/ twisting the dimmer several times, and then with the switch in park and the dimmer twisted substantially left, access the fuse box. Look underneath for the fuse with a tan on one end and several orange on the other. Check with a lamp/ meter and see if you have power there.