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Old 05-29-04, 03:44 AM   #1 (permalink)
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Lightbulb DIY for those looking to hook-up JDM one-piece lights

I recently got an email from a member asking how to wire the JDM lights to work with the USDM Legends. After composing a lengthy and detailed response with step-by-step instructions, I realized that others might be able to benefit from this info, so I've included the text of the email below.

Mods, if you feel that it might be helpful to put this in the FAQ or DIY section, feel free to add it there. Or if anyone wants to clean it up a bit, by all means have at it.

Happy reading!

**********
First off, here are the supplies you'll need. They probably shouldn't cost more than $25 or so:

1. Two 12V/30A SPDT relays (these can be purchased at almost any car audio shop...FYI, I had trouble finding them at Kragen, Pep Boys, and Radio Shack.) If you don't know what an SPDT relay is, just make sure it has the 30, 85, 86, 87, and 87a terminals.

2. Two H4/9003 bulb connectors (can be found at your local auto parts store). It'll look like a 3-pronged plug without the prongs and with 3 wires coming out the back end. Even though our bulbs are H4H, the H4 connector is identical and will work just fine.

3. A pack of slide connectors (at least 10) big enough to fit snugly over the relay terminals.

4. A couple feet of insultated power wire (12 gauge should be fine).

5. Some splice connectors (I used the ones for 14-16 ga wire). Alternatively, you can opt to solder a splice directly to the wire for a better connection.

6. Your typical wiring tools, i.e., wire strippers, electrical tape, etc.

Before you get started, you'll need to know some basics about everything with which you're working. It's probably important to understand the whole principle of wiring up your JDM lights to work with the low/high beam wiring of our USDM Legends. Because the H4H bulbs are dual filament, only one filament can be lit at a time. So you'll want to wire it so that when you turn on your low beams, a power is sent to the low beam filament, but when you flick on your highs, power to the low is cut and is instead sent to the high beam filament of the bulb. In order to do this, you need to use a relay. The layout of the relay is as follows:

30=main power
87a=normally closed circuit
87=normally open circuit
85=relay coil positive
86=relay coil negative

When you have a current going into the 30 terminal, it is sent out the 87a terminal. However, when you send power to the relay coil (85), it closes the circuit going to 87 to power that terminal while cutting the circuit to 87a.

Next are the wire designations from the headlight harness in the car. You'll notice that there are 4 wires going into the harness. The black one is the low beam ground. The red/blue wire is high beam ground. The remaining two wires that are the same color (don't ask my why) are the low and high beam positives. On the passenger side harness the wires are red/green and on the driver side, they're red/yellow. Of those 2 wires, the one that's closest to the black wire (low ground) is the low beam positive; the other one obviously is for the highs.

The only other thing you need to know is what each of the terminals are on the H4H bulb. If looking at the back of the bulb and imagining that the prongs are a triangle with the apex at the top, the top prong is for low beams, the right one is for high beam, and the left prong is the common ground.

Now, with all this info, you're ready to tackle the project. So, here's the step-by-step:

1. Using a splice connector, splice some power wire into the low beam + wire of the headlight harness. The length of wire you need will entirely depend on where you plan to mount your relay. Throw a slide connector on the other end of the wire and insert it into the 30 terminal of the relay.

2. Splice another wire into the high beam + wire of the headlight harness. Insert the other end into the 85 terminal of the relay.

3. Splice a third wire into the high beam ground wire of the headlight harness. Insert the opposite end into the 86 terminal of the relay.

4. Take the low beam wire of the H4H bulb connector and put a slide connector on the exposed end if there isn't one on already. Insert this end into the 87a terminal of the relay.

5. Insert the high beam wire of the H4H bulb connector into the 87 terminal of the relay.

6. The only thing left to do is to ground the common ground wire of the bulb. You can simply secure this to any bare metal spot near the headlight using a screw. I opted to ground it on the low beam ground wire of the headlight harness.

You may want to consider covering each of the exposed connections with some electrical tape so that you protect it from water/moisture, etc. Then decide where you'd like to mount the relays. After you've done all this to both headlights, you're good to go. What should happen is that when you turn on your low beams, the low beam filament will power on. Then when you flick on your highs, the low beam will cut off and the high beam filament will come on. There are other approaches you can take (and others have used) where you run directly off your battery but this will require you to add additional fuses. I chose to do it this way because frankly, I thought it was the easiest. Plus, it allowed me utilize the factory headlight circuitry and I didn't have to install any other fuses.

Wiring the headlights is the most important thing, but there's still the issue of the fog lights. So let's move on to those. To get the fogs to work, you'll have to wire in a separate switch. The fog light harness consists of 2 wires: yellow (+) and black (-). Decide where you want to mount the switch inside your car. Run some wire from the positive terminal of the battery to the back of the switch. This will require you to go through the firewall. Run another wire from the switch back out to the engine bay. Split this wire and run each to the yellow wire of the fog lights. You'll want to install an inline fuse on each of these wires. A 20 amp fuse should be fine but if it blows, you may need to push it up a bit (it may require some empirical testing to get the correct amperage for the fuse). The last thing to do is ground each of the negative wires on the fog harness to a bare metal spot near the headlights and you are done. As a side note, in search of way to achieve a cleaner and more OEM looking install, I'm currently working on a way to power on the fog lights using the factory fog light switch. These can be purchased fairly inexpensively (~$16) at Acura wholesalers. I just bought the switch a couple weeks ago but haven't had the opportunity to attempt to wire it in yet. I'm going to tackle this in the very near future and will pass a DIY along after I've done it.
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Old 07-18-04, 06:19 AM   #2 (permalink)
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Hey got a qustion Train. Have you done the foglights to the factory fog yet on the JDM?
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Old 10-08-04, 12:54 AM   #3 (permalink)
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If this helps, here's a diagram.

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Old 11-19-04, 02:08 AM   #4 (permalink)
 
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headlight bulbs

Dose anyone know where I can get those bulbs at. Looking for a hyper white version. Went to Autozone and they only had the H4 that are to fat to install with these headlights. You say they are H4H. any help would be great
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Old 11-19-04, 03:58 AM   #5 (permalink)
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Quote:
Originally Posted by 92ACLegend
Dose anyone know where I can get those bulbs at. Looking for a hyper white version. Went to Autozone and they only had the H4 that are to fat to install with these headlights. You say they are H4H. any help would be great

Buy them off ebay.
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Old 03-28-05, 04:40 AM   #6 (permalink)
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If you have JDM headlights, you have foglights as they are integrated (where the USDM highbeam is), but no, you don't have to use them if you don't want to.

There isn't a pre-built harness that you can get that's plug and play, but you can buy a harness and modify it if you prefer.
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Old 03-28-05, 04:57 AM   #7 (permalink)
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Yup. The JDM foglights are where the highbeams are on the USDM headlights. They aren't highbeam/foglights though. Just foglights. The JDM lowbeam bulb has a dual filament and acts as the highbeam too.

That said, to get everything working right, building your own harness would be better.
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Old 03-28-05, 05:37 AM   #8 (permalink)
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You'll need one relay for each function (low beam, high beam, fogs). As for the switch, you can basically run any switch you want; even an inexpensive toggle switch from Radio Shack. You can get an OEM switch for around $20 at the dealer.
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Old 03-28-05, 11:02 AM   #9 (permalink)
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Are you planning on making it blink? Well, in essence, yeah, you can pretty much hook it up to any trigger.

Why are your bumper signal wires hanging?
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Old 04-25-06, 08:10 PM   #10 (permalink)
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Quote:
Originally Posted by LegendGS
You'll need one relay for each function (low beam, high beam, fogs).
so how many replys do you need total to do the low/highbeams, and foglights for each side?
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Last edited by Ken; 04-26-06 at 07:36 PM.
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Old 04-30-06, 06:49 AM   #11 (permalink)
 
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Let me get this right,

all you need is 2 spdt 30/40 amp relays

on the 1 pc ka7 harness you connect the 3wires as followed:
1) Low Beam - 87a on relay
2) High Beam - 87 on relay
3) Ground - metal around bulb

from the Car Headlight wires you connect the 4wires as followed:
1) Red/Blue High Beam Ground - 86 on relay
2) Red/Yellow Low Beam - 30 on relay
3) Red/Yellow High Beam - 85 on relay
4)**What About Black/Low Beam Ground Wire?**

from the 1pc ka7 wire the following foglight as followed:
1) to a switch

from the 1pc ka7 wire the signal wire as followed:
1) connect it to the Car's Corner signal


Do this to both passenger and driver side.?

Last edited by ss812; 04-30-06 at 08:12 AM.
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Old 06-06-06, 05:09 PM   #12 (permalink)
 
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I am confused as well? on that diagram you have the high and low beams spliced into 2 wires from one? there are 4 wires coming from the car and only 3 wires on the H4H connector. The RELAYS have 5 prongs i get that one to connect eachother, but which do i splice and where is a good place to mount them? The relays that is...
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Old 06-06-06, 05:32 PM   #13 (permalink)
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Two wires from the lowbeam and two from the high beam make up the 4 wires. You don't split two wires from one anywhere.

So, basically, you have two wires from the lowbeam going to terminals 85 and 86 on one relay and from the highbeams on the second relay. You then have terminal 87 from the relay connected to the low beams wired to the low beam terminal on the bulb, and likewise on the highbeam. Ground the final terminal.

You connect terminal 30 on one relay to terminal 87a on the other then connect the remaining terminal 30 to battery power. That should be it.
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Old 06-07-06, 02:18 AM   #14 (permalink)
 
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yeah i figured it out for low's only but not the highs when i have my headlights on the high beam light on my dash is on but no highs at all not even when i flick it. I have the wire from my low stock harness running with the low wire to the H4H harness to one relay on the 85 terminal why is this the only way it works?
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Old 06-07-06, 04:11 PM   #15 (permalink)
 
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so what i meant to say is i have it ran directly together the stock harness to the JDM harness, to one prong on the relay instead of 2. It only works this way, i cant get my high beams to work yet only one of them works when i touch the wires together for the stock harness via JDM harness. I have it perfect in comparrison to the diagram up top but it does not work. any help would be appreciated...
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