The regular lights don't work on my Defender.

The switch is good, the bulbs are good, but the regular lights are not receiving any current. High beams work and all the other lights work. I was told that the black relay in the cabin (the one all the way on the left) was for the lights, but all the lights still work with all the relays in the cabin taken out.

Where could the problem be?

It was the relay(s). Problem was two of them were bad and when I switched them it did not help anything.

Check the headlight dip switch for current on both high and low levels also check the emergency flasher switch for sticking in the middle of it's travel you may need to tap
the switch several times to get to return to normal position . If that's the case replace
the emergency flasher switch . rovertec1958