This is how I wired up my Hella 500's. When you get these lights, I would highly recommend just tossing the wiring harness that comes with it and making your own with quality parts. Especially the in-line fuse holders. This is my first write up. I wish I had a few more pictures of the process, but I get into a work mode and always forget to take pictures. I'm not going to cover mounting the lights, because there are plenty of other threads about that.
Here are the basic tools you need. I might have left a few things out of the picture.
Here are the supplies you will need. There are a few things not included in the picture, like different colors of wire I had. I used 16 gauge wire. I already had the relay from the wiring kit that came with the lights, so I just used that until my Bosch relay comes in the mail.
Here is the fog light switch I ordered. It has the switch, wires, and plug that comes with it. I ordered it from ebay for $70. It was kind of pricey, but it is a genuine toyota part.
The first thing you want to do is remove the blank switch covers from the three holes on the left side of the gauge cluster. The easiest way to do this without messing up your dash is to put a wood screw into one of them and pull it out using the screw. Since the switch will take its place, you don't need the cover anymore and you can throw it away. After you have one out, you can pop the others out fairly easily if you reach behind with your finger.
Now you can assemble the switch. First take a razor blade or small screw driver and pop the little plastic clip open on the white plug. Then you can insert the wires into the plug. They only go in one way, so just as long as you don't have to force them in, you know you are putting them in the right way. After all the wires are inserted into the plug close the tab you previously opened. Test to make sure it plugs into the switch securely.
Here is a picture of the switch in the upright position. Starting from the top going down the wiring is as follow: 1 - Power source for the switch (this can come from the aux fuse box inside the cab or straight from the battery. if you choose the fuse box inside the can the switch will only work when the ignition is on.) 2 - goes to the 85 pin on the relay. 3 - negative feed for air conditioner controls. 4 - positive feed of air conditioner controls.
Now you need to choose your power source for the switch. The best option is probably the fuse box inside the truck, so that the lights can't accidentally get turned on without the key in the ignition. To do this use a fuse tape like the one in the picture for the materials needed photo. This power source will only need a 5 amp fuse, because all it does is supply the power to actuate the relay. It is safe to use the inside fuse box. I chose to tap into the fuse box under the hood, because there was only one available blank fuse in the inside, and that is taken up by my gps power. Either way you need to make sure the blank fuse you are using has power.
Now you need to start running wire for your switch. The fog light switch only goes in one position in the blanks (the far left). When you try to insert it, you will see what I am talking about. There are tabs on the switch that have to go into a specific hole. You could just cut out a notch for the tab with a razor blade, but I just chose to use the hole it fit into. Either way you need to run all your wires through the hole you choose. For the switch, since we already covered the top wire. Now we will move on to the second. Run a wire from the second pin on the switch to the 85 pin on the relay. Use a female type spade connector at the end to connect to the relay.
Now for the 3rd wire. This wire goes to the ac controls. Pop the ac control assembly out of the dash using a utility knife, but be careful not to break the blade. The wires you are going to tap into are the green wire and the green wire with a white strip. The green with white strip is the negative, which goes to the number 3 wire. The solid green wire goes to wire number 4. These wires are fairly small, so be careful not to damage them. I chose to splice in a wire and solder them back together and cover with shrink tubing.
The best way to get these two wire back to the switch is to run them through a small hole you seen in the front corner where the ac control pull out. It is hard to describe, but this hole is basically the easiest way to get the wires under the dash so you can run them to the switch. There is an opening under the dash that you should see the wires come through. It really helps to have second person for this part to push the wires through while you watch under the dash to make sure they come out.
Here is a crappy wiring diagram I made before I started just to have a plan for what I was doing. The main thing is just make sure you have fuses in place, so you don't start a fire if anything was to go wrong. Not sure how well you can see the numbers for the relay, but hopefully it helps.
I chose to solder all of my connections, and cover them with shrink tubing. Don't be scared of soldering, it really isn't hard. It just takes a little extra time. It really helps to have an extra set of hands to hold wires for you while you solder though. I don't trust the just crimp style connectors. That is jut my opinion, you do what you want, but I want the strongest and most reliable connection on my electrical work. If you use the crimp connectors, I would suggest at least using the weather proof kind with the shrink tubing that comes with it. For my butt connections I just mesh the wires together and give them a little twist and then solder them and cover with shrink tube. For ring terminals I use the crimp connectors and take off the plastic cover. I then crimp them on the wire and finish it off with solder and shrink tubing.
If you do everything right, the led in your switch will light up and dim with the rest of the dash. It will also, obviously turn on your lights. I chose to tidy up all my wiring with wire loom. It protects the wires, and gives everything a more clean and professional look. I hope all this can help someone. I welcome any comments or criticism so I can do better on my next write up .