I installed some aftermarket driving lights in my 4runner. When I was running the wires, I encountered the oddball circuit Toyota decided to use for their headlights. Instead of switching the positive leg of the headlight, toyota switches the negative side. This isn't unheard of, but it does present the problem of where to get a signal from the headlight in order to trigger the relay for the driving lights.
Ideally, the driving lights will be on only when the high beams are on. Additionally, a switch to turn them off would be nice. The stock headlight switch, when turned on, provides power to all the headlights fuses under the hood, regardless of the highbeam switch. I am not a fan of hacking factory wiring, so my hopes of using an add-a-fuse on the high beam fuse will not work for a relay signal.
My solution is to use an HID 9005/9006 pigtail.
Then, I can splice into the negative side of the headlight without hacking the factory harness. This is not my ideal solution, it creates additional connections in the headlight circuit that can be failure points/increased resistance, but it is preferable to cutting the harness.
Please post back if you have used other solutions for this problem. I'm certain I am not the only one.