Low beam headlights not working need help

[Lateralus]

Hi, I'm having a issue with my 2001 Cadillac Seville STS. Low beam headlights. They're periodically not working, even at times one will be working and the other will not. It comes and go's
I live on Georgian Bay in Ontario Canada. The problem started after getting my car stuck in snow and I suspect a wire harness or something has gotten moisture in it or something along that line. Now the low beam headlights constantly malfunction in wet weather and will not work again until what seams like they dry out. It takes parking the car in a heated garage or for the temp to drop to a constant -8 or lower for a day.
I have checked the bulbs/ballasts and all fuses and the headlight switch itself.
I suspect the problem is up under the front wheel wells. When stuck in deep snow and reversing a lot of snow gets thrown up into the wheel well shielding towards the front of the car, packing in there pretty tight. It could also possibly be from snow going though the front of the car at the bottom of the grill and under the radiator.
Now I'm willing to jack the car remove a wheel and tear the shielding off and clean all possible wiring but, as there is a lot of shielding I was hoping you could point me to a harness or something that would affect both lights as I do not have ideal conditions to be working on a car and it would be greatly appreciated if you could pinpoint it.
Thank you.

[Ohio Jim]

Lateralus,

Man it sounds like you are on the right track. I am not aware of the wiring placement, however, I would think to start at the lights and work your way back. I have been having a 'similar' situation with my battery cables on my '99 STS. The sun roof drains, I suppose, are leaking under the back seat. Every so often, the car would act as though the ignition was dead. I would clean the already clean cables and that would solve it for some time. At the worst moment, it would show up again. I have a post elaborating on this. Long story short, it has been more than a month with the problem not reappearing. I used a product made by CRC called 2-26. (See other post). Beware, can reads to give it 4 to 6 hours to dry. I ended up pulling the car into the shop were I work on a Saturday night and applying the product. It appears to have worked, as I think the problem was moisture related. You might research any electrical spray which displaces water, for a solution to your problem. You should be able to locate wiring diagrams to find the vulnerable areas where the breach most probably occurred. A second thought... my son has an '01 STS with a headlight issue only on one side. You mentioned ballast, so I am thinking you have HID's. I think his problem turned out to be a faulty ground!

Best of luck in your quest. If you cannot locate the diagrams, you seek, please let me know as I may be able to get them to you.

Ohio Jim