Light bar install (dimmer switch)

Hello everyone from Alaska here. We get very dark long winters and I am trying to install a LED light bar and some Hella headlamps on the van. I have wired many lights before on older vehicles by hooking into the dimmer switch by either plugging right into the headlight harness tapping into the wires there or using a fuse box.
Problem is I can’t find the fuse labeled driving lights or high beam lights and I have tried to test the harness that connects into the back of the headlight assembly switching high beam and low beam and the voltage on either of the wires doesn’t change. (One is ground, another one runs about 7v and the other one runs at 12 V.)
I guess I’m a bit thrown off because usually you have your ground and then whenever you have your high beams off one wire will read zero and the other one will have whatever volts you’re using for your low beam, and then when you turn your high beams on, your low beam will read zero and your high beam will read whatever you’re using for your high beam and that’s how you identify which one to tap into. Can’t get this result with this van.
Has anybody successfully wired aftermarket lights into the van listed above XSE? If so can you please tell me how you did it.