I was just curious, has anyone made from scratch a relay harness for the headlights( high, low, fog)? I have trying to find kits through Auto parts stores, but it seems like they don't know what I am talking about. I was thinking about a kit, but it doesn't seem like very good quality, but I could be wrong. Also does anybody have a step by step diagram and instructions. I have seem a final product but have not seem a step by step shot of this. I am very confused on the wiring and which terminals are what. I am looking to build separate setups for high low and fog so there is less load on the headlamp switch after I replace my original one. I am looking into getting a set of driving lights as well and that is why I wanted to build separate harnesses so they will produce less load but they will still work together like it did from the factory without melting the switch and causing a fire. Please Help. Thanks Brian

 

Yes, here is my setup:

https://plus.google.com/photos/11555...67774490549511

I used 1 cubic inch 30 amp automotive relays from Radio Shack, but you can find other brands, such as Bosch from most auto parts stores. I also used their 30A fuse holders with 10 gauge wires, that you might be able to see if you looked carefully. The reason I built my own was, like you, I was not satisfied with most of the kits that were available. I used 10 gauge wires throughout to minimize resistance. You can see the 3 wires from the fuse holders crimped into a large lug that's bolted to one of the studs on the starter relay. I also soldered that crimp to further protect it from moisture. The other thing about most kits I didn't like was that they all used a push-on connector for the relay, relying on friction to hold them in place. I drilled holes through the spades on the relay and used stainless bolts to fasten the ring-lugged wires to them.

I don't have a diagram to illustrate what I did, but here is the concept:

Intercept (cut) the wires going to the high/low beams of the head lights. Use the wires coming from the headlight switch to feed one side of the relay coil. Some relays have diodes across the coil, so you must connect this wire to the correct side of the coil. If they have a diode (my RS relays did not), you want to make sure you reverse bias it with the wires from the head light switch; ie, connect the wires from the head light switch (positive) to the relay coil terminal that is connected to the cathode side of the diode. The relay should come with a diagram for this. Ground the other side of the relay coil. So now turning your headlight switch on will activate the relays.

Run the wires from the fuse holders to one side of the switched contacts on the relay. Connect wires from the other side of the relay contacts to the wires going TO the head lights. This will already make a big difference in lighting performance, and save your head light and dimmer switches and wiring. But you can go a little further by replacing the stock wiring going the the head lights with heavier gauge wires. This would mean rewiring the connectors that plug onto the light bulbs.

If your car came with fog lights, you can do the same procedure to insert the relay into its circuit. Otherwise, you do it with the switch and wire you install yourself for the fog lights.

 

Amazon sells a heavy duty Headlights harness made by PUTCO, switchable from the headlights switch but powered from the battery, complete with relays.

 

Headlight relays were stuffed into a fuse box at the time I did a more comprehensive electrical makeover.
This was both tidy and convenient.

There is a pdf, subtitled "Relaying the Headlights" that contains schematics.