Here is how the INST lights work and it is a trick.
First, the HL switch has TWO power sources. One comes from the welded splice/ammeter wire and goes to B1, powering ONLY the headlights
The second power source is from the tail light fuse, goes to B2 at the switch, and powers tail, park, and INST lamps
The tail power........
when the switch is in park or head, and when the dimmer knob is twisted somewhat to the left, goes through the dimmer control, OUT on the tan wire and down TO the INST fuse. Through that fuse, and out to all dimmer controlled dash lamps on ORANGE wires.
1...So the park/ tail circuit has to be working