Head lights

Go to MyMopar and download a free service manual, or as "close as you can get." You may have to settle for Plymouth vs Dodge or vice versa

"The path" Think about the PATH that the headlights circuit takes.

POWER for both high and lo beams comes off the headllight switch and feeds to a terminal on the dimmer switch, which is a double throw switch. So stomping it switches the output of the headlight switch to either hi or lo. From there on separate wires, the hi and lo beam power goes THROUGH THE BULKHEAD connector, and around to the lamps. At some point (I don't know, likely the driver side headlight connector) the wire branches off to feed the other side.

There is only one ground for each side, usually tied together and connected at the radiator support

MOST LIKELY is a bad connection at the dimmer switch, a bad dimmer switch, a bad connection at the bulkhead connector, or a broken connection at the driver side headlamp