There's no need to re-invent the wheel, you can download a service manual from MyMopar for free
But since you did not tell us what you are working on ^^THAT DIAGRAM^^ (the one posted above) may not be correct. It is in fact only correct for the newer models which keep the parking lights on with both tail and headlights
On the earlier models, the park lights are picked off from the P terminal which as you see is not connected in the diagram.
A few comments, that can be important and helpful when running down problems
The BLACK power wire to B1 is 1 of 2 power feeds. That wire is NOT fused as it comes from the "welded splice" from the big black in the ammeter circuit. B1 ONLY feeds headlights and NOTHING else
B2 gets fused power and supplies everything else, including instrument lamps. That circuit is a "trick"
HOW THE instrument circuit works. B2 must be powered from the fuse, and the tail or headlights must be on, and the dimmer switch rotated somewhat "to the left." At that point power FROM the switch DIMMER control goes OUT to the INST fuse on TAN. At the other end of the fuse, all dimmer controlled lighting is distributed on ORANGE wiring from the fuse box
The yellow is the ground / switch leg for the dome circuit. It works the same as the door switches........when you twist the dimmer control all the way left, a switch contact makes and grounds the yellow, which completes circuit for the dome/ courtesy lamps.
