Disclaimer: While this worked for me and should be fine for any 4th gen proceed at your own risk.
Ok, so I decided to look into this some more and see if I could come up with a solution. This is what I have tested and works. This is on a 2016 Ram 2500 but I imagine 2014-2018 are probably all the same?
Side note: If you are using your high beams for DRL's you are going to want to disable them or switch them over to the low or fog beams (can be done with AlfaOBD). I had my high beams as DRL's but simple changed it to the low beams.
Goal was to tie my light bar into the high beams and also have a separate switch to turn it on with protection (I actually have multiple lights hooked up to separate switches and high beam but going to show just 1 here for simplicity).
I found the high beam wire coming out of the BCM inside the cab. There is a left and right HB wire but the right was easier to get to. The wire is hard to get to but can be done.
The wire you are looking for is the WT/GY (white/gray) wire coming out of the C1 connector pin "2" on the BCM.
Here you can see where I spliced in to the WT/GY wire coming out of pin 2. It's a 18awg gauge wire. I stripped back the insulation and soldered it but you might be able to use one of those crimp splices but there isn't much room in there to get a pair of pliers in there to crimp it. Like I said it's hard to reach but can be done.
Here is a diagram of how I hooked it up. If using just the high beam switch just ignore the switch I have shown. Like I said, I have multiple lights and switches so if someone is interested in that I can make another diagram showing that.
