Main dipped headlights not working

There are no relays unless someone has added them.

OK, let's start 'from stratch' on the headlight problem

Start with the switch "on" and try the dimmer both positions. any lights? With the switch on, measure the incoming power (terminal B1) as well as outgoing (green) coming out of the switch. You should have good solid battery power there, within a few tenths of the battery voltage.

If so, move down to the dimmer, and check the green and "whatever is hot" of the other two terminals. Same thing..........within a few tenths of battery. "Double check" at battery to see what it reads

If you have it there the only thing left is the two terminals through the bulkhead where the hi and low beam power feeds. If you can acces them, check. If not, move out to the headlight sockets themselves, checking right at the headlights.