Headlights won't operate, Understanding headlight circuits and relays Options

[Prospectfarms]

When I pulled the headlight switch all the way out last night my lights would not open, and did not illuminate. No pop-up, no light. Parking and brake lights operate.

Best way to test the headlight switch? I'd like know how to test the wiring "downstream of the switch too. What circuits are closed when the headlight switch is pulled all the way out? Asking 'cause I was also seeing an intermittent alternator light that makes me think "voltage drop" at some connection and because I don't fully understand how the headlight switch acts on all the relays.

As I understand it, the relays at the bucket assemblies activate their respective motors and the high-low relay responds to input from the switch in the steering column. Since the lights pop-up and illuminate when the switch is pulled, the dash switch must directly energize a pin on all three relays?