HEADLIGHT WIRING UPGRADE - CUSTOM HARNESS - PICS UP ENJOY

Last Updated: Feb 24, 2015
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So the first thing you need to do is figure out what you are going to do with your lighting, are you going to run high power bulbs down the road, or do you just want a bit of an improvement for everyday driving.

It makes a difference as to which products you use.

Now get a multimeter, Pen and Paper and do the following.

Turn the Multimeter onto DC 20 volts( some may be different but you need at least 16 volt capability to measure this )

start your truck, turn off the stereo and all accessories, and turn on the headlights. Let the truck idle for a minute or so.

Now measure and write down your battery voltage, it should be around 13.8 - 14.4, if not you might also consider getting you battery tested, and or your alternator tested to make sure they are in good working order.

Now take the black(-) lead of your multimeter and place it on the posotive battery terminal, and take the red(+) lead and touch it to the LO beam headlight on the drivers side. It should not read 0 and it should not be anywhere near Battery voltage. Most of the time it will be around 1.5 - 2.5 volts. Write this down, this is the (+) voltage drop for the drivers low beam. Now do the same for the passenger low beam, again write this number down, and then do the high beams (obviously you will need to turn the lights from lo to high beam for this part of the test ) on both sides and write these numbers down. You should have 4 numbers written down. Now take the (-) black lead on your multimeter and touch it to the negative battery terminal and test the ground on both headlights ( again you will need to switch between lo and high beam and write these numbers down.

Heres the fun part, you need to be able to add for this one...LOL

take the (-) and (+) from each beam passenger hi, passenger lo, drivers hi, drivers lo, and add them together, you should now have 4 numbers. These represent the total voltage loss at each beam.

Now figure that the LUMENS, or light output of the bulb will be directly affected by the input voltage of the bulb and you will see why a 2 - 4 volt drop is very significant.

10.5V : 510 lumens
11.0V : 597 lumens
11.5V : 695 lumens
12.0V : 803 lumens
12.5V : 923 lumens
12.8V : 1000 lumens ←Rated output voltage
13.0V : 1054 lumens
13.5V : 1198 lumens
14.0V : 1356 lumens ←Rated life voltage
14.5V : 1528 lumens
( the above is from DS lighting)

Credits

Created By: gravity5

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gravity5 +1y

This should have been the first step but collect all of you supplies....about 30 feet of 10 or 12 gauge wire, connectors, heatshrink, a soldering iron, solder, flux, wire cutters, wire crimpers, a flashlight, a test light/multimeter, fuse holders that are good to about 20 - 30 amps with 4 spots, 2 headlight wiring plugs, 4 relays, and some misc bolts, nuts wahser, and aluminum to make brackets.

gravity5 +1y

Here you can see the bare engine bay, and if you look closeley you will see 2 of the 4 realys mounted on the drivers side by the power steering fluid resovoir.

gravity5 +1y

Now take the 2 headlight plugs you bought and de pin the 3 wires in each....You dont need to even buy or use these it just makes it cleaner and easier to identify wires when changing headlight bulbs. And the picture shows the reason to de pin the wires....the wires the kit come with are 18 gauge ( crap ) and the wires we are going to use are 10 gauge (or 12 if you don't plan on higher wattage bulbs later )

you can see in this picture I have installed the spade connector on the 10 gauge wire. The H4 headlight bulb uses a spade connector that is around .300 wide and most of the ones you buy are .250(1/4 inch) make sure you get the .300 ones or they won't slide onto the connector on the bulb.

gravity5 +1y

Now you need to test the wires in the factory sockets...

these are the 3 connections on an H4 type bulb...1 will be ground and the two others will be low and high beam respectively, test the 3 wires and write down the layout.

the one on the left side of the connector should be ground (looking at the plug from the wire side not the headlight side) the other two wires differ, as the european configuration and the north american configuration are different.

No big deal though as long as you know which wire is ground.

gravity5 +1y

Now make a bracket and mount you fuse panel and relays.

I made mine from 1/8 aluminum plate, and mounted it to the car with M6 bolts using factory holes. And then mounted the fuse block to the 1/8 plate with Titanium M5 cap head screws thru 2 holes I had tapped into the plate when I made the bracket.

gravity5 +1y

Now for the wiring, the fun part

First off we will start by doing the trigger wires to the relays.

Now that you have your wire colours labeled as to where they go and what they do, dut off the factory headlight plug about 1.5 inches from the socket, this should give you plenty of room to run the stock wires to the relays....For these connections Blue Crimp on or Solder on spade connections are what you will use, heatshrink them if possible.

Run the factory ground wire to TERMINAL 85 on both relays, you will need to split the wire to do this.

And run the Low and Hi beam wires to Terminal 86 on the realys ( 1 relay for high beam wire and 1 relay for low beam wire.)
Thats it for your trigger wires, DO NOT Ground the relays, some cars need both a ground and a posotive to have the circuit complete.

Take the aftermarket plug that you removed the wires from earlier, and drill out the 3 holes slightly to make the 10 gauge wire fit and clean all of the shavings from the holes.

Make a ground wire that has a ring terminal on one end and a .300 spade on the other end, make it long enough to go to a good solid ground point and to the headlight, with some slack of course. push it into it's appropriate slot in the connector. Now make 2 more wires with a .300 spade on one end and a .250 spade on the other end to go from the headlight to the relays( the .300 goes to the headlight side ) and push them into the connectors. Run the high beam back to the highbeam relay and the lo beam to the lo beam.

Super simple.

gravity5 +1y

The wires from the headlight to the relays go to 30 on the relays.

Now run wires from the fuse block, to terminal 87 on the relays...for the wires on the other side of the truck/car braid them as shown below to make the install cleaner.

and then run a 4 gauge wire from the positive battery terminal to the fuse block( thru a fuse rated between 40 and 80 amps depending on the wattage headlamps you run ) and plug all of the fuses into the fuse block, check all of your connections and turn on the headlamps, check both for lo beam opperation, and check both for high beam.

If there is any porblem turn off the headlamps and check your wiring.

RE AIM your headlamps, they will probably need to be aimed a little lower than before.

Enjoy your more powerful and more reliable headlights.

( Also it is now easier to add on LED headlight accents and they will be brighter too.

hex0rz +1y

Dude! Grav, you are the man! Lets see some before and after pics?

Very quality write-up!

gravity5 +1y

Unfortunately this car had 2 melted stock headlight sockets....thanks to shitty honda wiring and some 100 watt bulbs....LOL.

But I will assure you there is a very large improve,emt in light output....And I am going back to the PIAA GT-X bulb now, just waiting for them to get in.

hex0rz +1y

100 watts! Lol! wow! Well, I wanna definitely see how bright you can get 'em, lol!

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