No relay on that circuit. You have already checked the fuses hopefully? Check for power on the red/yellow wire going into the multifunction switch, and on the red/black coming out and going to the low beam headlights. If you have power going in and not coming out, it is the multifunction switch.
Ok I found a total of 4 fuses. 2 for low beam ( 1 each side ) and 1 for multi switch headlamp and 1 for high beams. All fuses are good. I don't have a way to check the power on the switch. I am in Alaska visiting and he does not have to many tools. The runnin lamps work but no lows.
Well unless you have an extra parts truck with you and just want to start throwing parts at it, you are going to have to do some diagnosis. Doesn't matter that the park lights work, completely different circuit.
Fixed: I did a little more searching and it seems others have had similar issues. And several of those cases turned out to be the low on the lamps burning out at the same time. Which is what he told me. He got in his truck to leave for work turned on his lights and they flashed and went out. Anyways it turned out both lows were dead. Got new lamps and they are fine now.