[Blas]

The power for the low beam headlights is routed thru the headlight switch.
The first click on the headlight switch is the running lights and the second being the low beams.
You power-up both headlights via the headlight relay. (one wire from the switch powers both L & R)
Each headlight (R & L) has its own fuse (but as stated earlier; a common power source from the relay that splits) so if one low beam works you need to check power at the individual fuses (left and right – low beams fuses) Check both the “power in” side of the fuses and then the “power out” sides of the fuses. If you have power thru both the fuses then your problem is down-wire from the fuses.
Did you check for power at the headlight socket?
I would bet that the problem is a bad ground at the headlight socket.