The ONLY thing that high and low beams have in common is the stick (multi-function switch) on the steering wheel and the Body Control Module itself (the switch signals the BCM to operate the light relays). Highs and lows have their own set of fuses and relays. Your DRL and fogs don't depend upon correct function of that switch assembly.
As a test, please pull back on the thing to 'flash' mode to see if the high beams come on independently. This operates the high beams independently of the BCM and other portions of the multi-function switch.
If you can flash your brights that way, you've got a diagnostic issue on your hands. It could be something as simple as a lost ground to the multi-function switch, a failure of the switch (though it would have to be major to kill both sets of lights) or it could be a whole lot uglier at the BCM itself.
Since when did the '08 have DRL??? Ah - never mind .. see you are headed TO Arizona, living in Canada. Not sure how they wired those.
So to be clear, using the 'flash' mode on the high beams does NOT work? Fog lights DO work with the control as appropriate?
If you can read a pretty simple schematic, you'll see what kind of conundrum you've created here. Attaching '08 headlight schematic, though DRL operation (may just be a function of the BCM programming) is not in evidence.
Yes, correct, the fog lites only work with low beam selected, and still go off when hi beam is selected or if flash is selected.
Thanks for the Schematic I can read it. I still cannot figure it out so will take to dealer tomorrow and put off my trip till fixed.
If it was ONLY a high beam problem, there would have been a chance that we could sort him out without a trip to the dealer. Unfortunately, he's dealing with a failure of both high and low beams. If you have only a high beam problem, it may be a much less painful solution.
I have a similar problem 2009 Santa Fe. Driverside low beam not working. Took it to stealership since bumper to bumper warranty which obviously does not cover this issue and so wanted to charge me 250 dollars for a headlight relay replacement. Part is only 16 dollars. I'm going to DIY this weekend and will post updates if Op is interested.