High beam/low beam HID retrofit question

[warrior]

Since I'll be doing a HID retrofit into my low beam and keeping my high beam as is.. I'm going to have a problem with switching between the two since when you flash your highbeam, subaru's electrical system shuts off the lows.

Now, I believe from reading that subaru switches grounds.. so if I custom make a relay system for each.. one for the lows, one for the highs and have a permanent ground.. would that fix this problem?

I believe I'll have it wired like so:

86 - high beam signal
85 - ground to chassis
30 - battery
87 - output to high beams

Same for the low beams.. make sense?

[warrior]

Did some researching, according to Daniel Stern this won't work for ground-switched systems.

Hmm.. basically, how can I separate the two from each other.. if that's even possible.. secondly, does anyone have a diagram of the headlamps electrical system??

[warrior]

Update:

Ok, so I figured it out... thanks for your help guys :P

For future reference because I know someone will follow what I'm doing and will need help. Basically, a simple little diode is needed that goes from high beam common ground wire to low beam common ground wire.. in that direction.

A diode only allows flow of electricity one way so this way, when you switch to highs, the diode will still allow ground signal to go to the low beams.

:)

[rougeben83]

Or you could just permanently ground the low beam to chassis. It'll stay on when you flip the high beams on.

That's what I did.

[warrior]

Or you could just permanently ground the low beam to chassis. It'll stay on when you flip the high beams on.

That's what I did.

I thought about that, but according to an article on Daniel Stern's website, he said this will not work?? I figured that would be the easiest way to do it as well.

Maybe the ground switched system only applies to dual filament bulbs and it could be potentially dangerous if both filaments are hot. Since the JDM's are a two bulb system, maybe it can work.. where did you ground it from and to where??

I was going to use this diagram as a reference and wire it this way:

https://sl-i.net/FORUM/images/imported/2007/04/relaycircuitgif-1.jpg



Many Japanese vehicles, as well as a few others, use a "ground-switched" headlamp circuit. In these circuits, the headlamp and beam selector switch break or complete the ground side of the headlamp circuit, rather than the feed side. On these systems, it's imperative to use both negative and positive existing headlamp wires to trigger the relays. It is tempting to run the existing headlamp feed wire to relay terminal 86 (trigger feed) and simply find a convenient ground for relay terminal 85 (trigger ground). However, this will not work with ground-switched systems. Run the vehicle's existing feed wire to terminal 86, and run the vehicle's existing ground wire to terminal85.

[rougeben83]

...it works for me. And I don't know how many others that did HID's on their cars on NASIOC.

I would suggest you go over to the lighting section there. They have a good sticky regarding HID's (granted, it sounds a little too elitist at times, but yeah, there's good info there).

[ProdriveDreams]

I did it, and ooo how it works.

[backpack09]

? with HIDs or halogens? With halogens you will be drawing a lot more watts through your already anemic stock wiring to fire both bulbs.

[warrior]

Instead of waiting for someone to reply, I went ahead and made a diagram of what I believe my harness will look like.

http://img66.imageshack.us/img66/7403/9007harnessqd3.jpg

Since I have a switch to turn on my low beams, which in turn makes the Power Common hot, I've decided to always ground the low beams (thank you prodrive and rougeben). This way when I switch to high beam by either flashing or turning them on, the low beams will always remain grounded and the HIDs (once my retrofit is complete) will stay illuminated. I can turn them off by turning my switch off.

The high beams I want to upgrade to thicker gauge wire so I can insert 100watt high beams. Since the Power Common wire goes hot once I turn on my low beams, and it too is connected to a relay, once I flash or turn my high beams on which switch to the high beam ground on the connector that's connected to the relay, in turn it opens that circuit allowing flow from battery to turn on my 100 watt high beams which will be separately grounded.

[rougeben83]

You can just use one relay and that's for the low beam. I have a 30amp running to a 12g wire harness.

For the high beam, I just used the factory connections; you won't be drawing anywhere near the current of an HID at startup using those H3 bulbs the retrofit kits have for high beams. In addition, aside from flashing people (the real reason why you retain hi-beams on retrofit kits), you won't be using them for long periods of time since they don't even add that much additional lighting to the HID's - this is going to be true even with 100w bulbs. If you want additional lighting, get some driving lights. You can wire them to to a relay triggered by the highbeam switch and use them as high-beams instead.


I didn't bother running the ground back to battery. I just use the chassis for the ground. I have grounding wires that daisy chain all the battery, engine, fenders and firewalls so I'm guessing the difference in voltage drop between either source would be minimal.

[warrior]

I don't want to add anymore driving lights onto the car.. Mark installed 100watt high beams to his JDM Projectors and he said it did wonders.

I think I'm going to leave my wiring the way I have it and see how it works.. I'll test it all out before.. I'm just a little concerned about my high beam relay setup (not sure if it will work) but I'll only know once I hook it all up :D

Thanks for your help!

[ProdriveDreams]

Your wiring diagram appears correct to me. I see no problem with the way you have it set up.


? with HIDs or halogens? With halogens you will be drawing a lot more watts through your already anemic stock wiring to fire both bulbs.

I actually did mine with HID's, but i did run a wire straight from the battery to both highbeams. The only problem with this setup is that high beams do not turn off with the ignition switch, and when your headlights are not on, the highbeam indicator works opposite of intended. Meaning when my car is off the highbeam indicator is still on. I will eventually re-do my silly harness from H4 to JDM+HID ballast, and when i do i plan to add relays for both high and low beams, and then add 100 watt driving lights.

Not the perfect solution for everyone, but im fairly certain a simple diode would put an end to the High beam indicator problem.