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Head light relay mod write up....WOW what a difference

198K views 474 replies 125 participants last post by  87 Wrangler 
#1 ·
Head light relay mod write up with pics...WOW what a difference

High everyone,

I am going to attempt to document my method of the headlight mod using relays. This is my first write up ever and I don't pretend to be any kind of a mechanic or expert of any kind. I am sure I could have done some things better but like I said I am a total amature at this stuff and did the best I could. I was amazed at the before and after pictures of the difference in brightness.
As we all know the factory headlight system leaves much to be desired. Using under sized wiring and running all that juice up through the switch is well, just plain cheezy to say the least. I can thank this forum for the idea and the guidance to complete this mod.

To start out I used this diagram:



What you will need:

2 30 amp 12v dc relays.(one for low beam and one for high beam)..local auto parts store
A bunch of 12 ga wire of a few different colors
2 inline fuses 12 ga with 25 amp fuses
various connectors and such

I started out by cutting the wire at factory headlight connectors. I took the pins out of the connectors and cleaned them all up. Then I soldered the 12 ga wire to the factory pins and reinserted them in the connectors (I didn't want any of the factory 18 or 20 ga wire or whatever it is anywhere in the circuit). I would suggest going to the auto parts store and getting new connectors. They are an off the shelf item and don't cost much.

Use a pick or a connector disassembly tool to get the pins out of the connector.



I cleaned them all up and soldered my 12 ga wire directly to the pins.



I then followed up with 3 layers of shrink tube and reinserted the pins back into the connector. Be sure the locking tabs are sticking up plenty far and listen for the click when you stick the pin back into the connector, gently tug back out on the wire to confirm a positive lock. I also coated all connections with dielectric grease.





Next I soldered in a T splice to run the other headlight and ran the loom behind the grill.



Using a pick I split the wire and inserted the other wire into the split then twisted them togeather. After soldering I used plenty of electrical tape, then zip tied over the electrical tape to keep the tape from ever unravelling and finally it will go into loom.

Next I mounted the relays on the inside of the wheel well behind the driver headlight.



I used crimp on female spade connectors to connect to the relay pins but I should have used relay connectors designed for this purpose (I will redo sometime with a solder on connector sometime).

I then ran power from my battery to the relays. I used two seperate power feeds but looking back I only needed one power feed wire then I could have soldered in a T splice just before the relays to run both relays...oh well, lots of lessons learned during this project.

On each of the power feed wires I soldered in a 12 ga 25 amp fuse holder. Be sure to get a good water resistant one with the push on cap like this one.



Loom and ziptie everything up and enjoy your much more reliable and efficient lights!!
On the before and aft pics the left headlight looks brighter because I am parked crooked in my garage and I am pretty close to the garage door.

Before:

After: Not only are they much brighter notice how much whiter the light is....can't wait for it to get dark and go for a drive... hehe


And while I am at it just for fun my white face gauge mod:






 
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#5 ·
I cut the wires at the connector on the back of the headlight...these wires will power your relays for the switching action. You will only use the wires from one headlight. I believe the white one is high beam and it goes to one relay. The green one is low beam and it will switch the low beam relay. Black is ground.
 
#6 ·
Whitefacegauge.com. They gave VERY good service. They have a great website with good detailed instructions. Kit was like $25 shipped. I also bought some flourescent orange paint for the needles from a different outfit. The paint is like $8 for a teeny little jar but I had plenty left over. I used a toothpick to apply the paint...worked great. probably the best mod I have done so far as far as bang for the buck.
 
#4 ·
A few Questions:

These are stock, sealed headlamps?
What was your total time on this project?
Do you have more pictures of the overall under-hood appearance of the wiring? How much clutter does this add?
You mention using water-tight in-line fuses and yet your connections at the relays are exposed. Any solutions to this issue?
 
#7 ·
These are stock, sealed headlamps?
Yes these are the stock sealed beams. I used the existing lights that were in there...really brought em to life.

What was your total time on this project?
Total time was a complete day..prolly around 8 hrs. I am sure it could be done much faster but I had the attitude of just tinkering and having fun all while learning.

Do you have more pictures of the overall under-hood appearance of the wiring? How much clutter does this add?
Yes I can snap more pics if you want. Does not add much clutter for what you get. Well worth it and if you do a good job and do not rush it looks pretty cool. I was out of black loom and the auto parts store only had blue. I was not sure if I was going to like the blue but now that it is all done I must say it is not bad at all.

You mention using water-tight in-line fuses and yet your connections at the relays are exposed. Any solutions to this issue?
As I stated in the write up you can buy relay connector plugs and looking back this is what I should have done. I will upgrade this in the near future and update the mod.
 
#8 ·
I've got a similar setup.

If you think it's an improvement now wait 'til you throw in an E-code H4 conversion and higher wattage bulbs!(Assuming you plan on upgrading the headlamps from the sealed style). My lights out perform most aftermarket HID kits that I see on the road in terms of usable light and the E-code are damn good at putting the light where I need it and not in people's faces...

Only differences are that I separated mine from the alternator completely (means I'm getting about 12v steady as opposed to 14v-16v from the alternator-mine jumps around quite a bit sometimes-that's mostly because I'm just picky about light flicker though...) And that I used a pre-made relay harness (got it for free)... Same setup as yours but I need to clean up the wires (it's a one size fits all so many wires are far too long for the jeep, I coiled them and zip tied them out-of-the-way for a rainy day.)
 
#10 ·
#16 ·
Yes it should work on both. Then you can upgrade to headlights that have replaceable bulbs & really throw some light.The sealed beam halogens & the H4s have the same plug,so that makes it an easy mod.
 
#12 ·
Someone wanted more pictures of the overall job:

I am also running my KC lights from the battery to a relay so I am starting to get a bit of a mess going. I will be looking into a fused terminal strip or a breaker box mounted on the firewall to clean up the mass of wires coming off of the batt. I am also looking into a relay block to clean up the relays as well





The blue loom going around behind the engine carries the main power feed to the relays located on driver front wheel well.



 
#15 ·
I'm in the procurement process now on my Headlight relay project on my CJ7. I found some nice distribution blocks at pick a part on 80 - 90's GM trucks. They are open studs but a high plastic wall around so you don't get accidental grounds to tools and such. I also found some nice heavy relays on S-10's with AC. Yours looks like it came out very nice. I hope mine works out as well. John
 
#19 ·
What wattage are those bulbs? I did the H4 conversion as a complete noob and didnt take into account bigger bulbs might = bigger wires.

I ended up burning out the socket and damaging the other (hence the relay mod). Its been fantastic ever since, but just something for those with higher watt bulbs to think about if on the stock setup
 
#20 ·
Just an update on my relay Mod. Since doing this mod I have went to the Rampage H4 lights and it is an unbelievable improvement!
My relays with the open push-on connectors left some to be desired though. Below is a pic of the original relay mod.



Then I decided to go with the relay socket like in the pic below to tidy things up a bit.



The problem is when I add more mods like additional lighting, electric fan, or what ever else tickles my fancy the mess of relays and fuses will begin to be too cumbersome so I decided to look for options to make things better and more of a factory/professional look so came up with this.



It is a fuse relay panel from a 92 S10 blazer. I completely gutted it, cleaned it up and started from scratch, rewiring it to my custom needs. The relay/fuse box will accomodate up to 6 relays and a dozen or more fuses. It is totally enclosed top and bottom with a hinged lid.

Below is the wired and installed results

I used weatherpack connectors so the whole thing can just be unplugged, removed and modded or serviced as needed

Before​


Since my horn was not being used I removed it and used the space to mount the power center.

After​








 
#21 ·
I did a similar relay conversion (I used separate fuses for high and low beam circuits), and I agree, this is the cheapest, best upgrade in terms of bang for the buck.

To others reading: before you waste money on expensive lights etc, do this (actually since high performance lighting is more sensitive to voltage loss, this should be done first, regardless)
 
#23 ·
I'm so glad more Jeepers are doing this instead of HIDs in H4 conversion sockets...
 
#24 ·
What a great mod, congratulations, I did this myself before, and I used H4 headlights with Hella headlamps, but I never thought about using a fuse box, that's awesome. I want to follow your example, will start looking for a box. Congratulations again!
 
#26 ·
It was easy to gut and rewire. I used all of the existing connectors, i just soldered and used dual wall sealing shrink tube on each splice to attach my new leads onto the existing wires according to what gauge I needed. I had to open up a couple of the terminals and recrimp my new wires to them because there were not enough terminals wired for 12 gauge for my needs.

The terminals were a different style that I had never seen before. They are super heavy duty....much heavier than your average spade connector.

The other benifit is I am going to run a 2 gauge wire to source the box from my battery so I can eliminate all the wires coming off of my battery. In essence it serves as a terminal block/strip as well with built in fuse panel.
 
#28 ·
Nice thread, and I just noticed tonight that I have one headlight out... I will be doing some of this soon..

Subscribed!! :cheers2:
 
#32 · (Edited)
:thumbdown:

jumpers may havr voltage drop of their own.

you could run a 12 ga wire direc to the bul (also be sure the bulb ground is good) . you can also read voltage drop (under load) from hot terminal on battery and from ground side of battery to ground side of bulb. This will show how much power is being lost.

[I posted this reply on a tablet. Sorry about the sucky spelling. Looking at it now, I'm embarassed ]
 
#33 ·
Wow, way more info than I was looking for but thanks! I just want to jumper one light at night against my garage door to compare them side by side. I subscribe to the KISS method and I like to see how it will/will not work before jumping into things.

I really like your suggestion of measuring the voltage drop! THANKS!
 
#35 ·
evanjeep said:
Did you keep the same wires from the switch that dims/bright to the relay and just wire them to the relay? And power come from the battery to the relays to the lights bigger wires= more power to lights? Is that right. Im trying to figure it out lol
Got it right exactly. There is a wire for low and hi beams. Those two go to a relay each which then goes to each light. One relay powers low and one relay power high.
 
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