View Full Version : Need some info on the headlight wiring harnesses.

02-04-2006, 12:44 PM
Yep, definitely think that upgrading the harnesses will help light output, so I would like Pictures, diagrams, whatever that can help me find where the relays are, and where the wiring goes.

CN: I want all the info I can get, because I want to make my own wiring harness (smaller guage wire).

02-04-2006, 02:36 PM
Just get another set of relays and hook them up at the end of the original harness.

02-04-2006, 02:37 PM

02-06-2006, 06:41 AM
What sha_zapple means is instead of trying to replace all the existing wiring for the headlamps, if you simply wire in new relays at the end of the existing circuit you will save yourself a lot of time and headache.

In this case you would use the existing 12V headlight circuit simply as an interposing relay setup where it would drive another relay instead of the headlights directly. The new relay circuit could be wired straight off the battery with a properly rated inline fuse and with a larger gauge wire so there is less resistance, meaning less voltage drop across the wires, and therefore more voltage at the bulb.

But it may not be necessary. The first test would be to measure the voltage of your "system" compared to the headlight voltage. Best time to do it would be after returning home from driving for a while. Turn on your headlights and measure the voltage across the battery terminals and then across the headlight. If there isn't much of a difference then the exercise may not be worth much as all. If you see a significant drop, then you are loosing voltage in your existing wiring.

Another thing to keep in mind is that all the loads together add up for voltage drop. It isn't only your headlights, it's your wipers, rear defrost (a big one) HVAC, Radio, and then the signal, parking, and brake lights. Even if you have your headlights tied to the battery with as little resistance as possible you will still never get more voltage then what the system can put out under load.

So another way to raise the light output more effectively is to reduce the load on your system at night. For instance: Changing your parking, signal, and brake lights to LED's. By doing that I gained 1.0 to 1.5 Volts on my system. The LED's draw very little current and therefore very little voltage drop too! I have seen a noticeable improvement without any wiring changes.

If you add up all those bulbs together, you've got just as much wattage there as your headlights put out.

02-06-2006, 12:47 PM
...measure the voltage with parking lights on, then with headlights on. that'll tell you exactly how much strain your headlights add.

02-07-2006, 06:34 AM
I agree with the above. the stock system was pretty well engeneered to provide the right amount of electricity to the headlights. running straight power isnt really going to help the output a whole lot. its just these lights in general dont have a great output. If you are getting a voltage drop when running with everything on pick up a new battery. an optima red top will get rid of your problems considering your alternator is in good shape