Welcome to the forum, the quickest way, may be to have all trouble codes checked, manufacturer specific, everything. See if the codes point to anything? When you check a fuse, you also need to use a testlite, see if fuse circuit is hot. Even if the fuse is good, if there is no voltage, the circuit is dead.
On and off, bright and dim are controled on the headlamp ground circuit. There is a headlamp relay in the left instrument panel junction block. When the relay is energized, it completes the ground circuit for the headlamp. There is voltage to coil side of relay, not sure if that is battery voltage, didn't track the circuit, use a dmm. The BCM grounds the coil side of relay. The headlamp switch grounds a signal from the BCM, that is how the bcm knows the switch was turned on. Just speaking for myself, without a code or something to point us in the right direction, it's hunt and peck the wiring circuits.
Monday, May 22nd, 2017 AT 1:01 PM