69 273 headlights wont turn on

The headlights ONLY power (not park and tail or courtesy lamps) comes off a splice in the ammeter black wire circuit under the dash and goes direct to the headlight switch. From the switch, power goes to the dimmer, and then out through the bulkhead to the low and high beam headlamps.

Easiest thing to do first, is access the dimmer switch and turn on the lights. See if you have power on two of the dimmer terminals. Power comes in one, goes out on 1 or other of the remaining terminals to select high or low beam