Skip to content
View in the app

A better way to browse. Learn more.

Ultimate Subaru Message Board

A full-screen app on your home screen with push notifications, badges and more.

To install this app on iOS and iPadOS
  1. Tap the Share icon in Safari
  2. Scroll the menu and tap Add to Home Screen.
  3. Tap Add in the top-right corner.
To install this app on Android
  1. Tap the 3-dot menu (⋮) in the top-right corner of the browser.
  2. Tap Add to Home screen or Install app.
  3. Confirm by tapping Install.

Relays & heavy wire to upgrade headlights

Featured Replies

I'm working on getting better output from my headlights on my 95 Legacy and the first step is to run some heavier wire to the headlights, and use relays to switch the power through the wires. I have it all wired up in what I think is the right way, but I'm getting some weird results.

 

I have two specific questions:

1) Has Subaru done something weird with the factory wiring that would make a normal relay set up have problems?

 

2) Has anyone done this set up with a similar age Legacy, and how did you do it?

 

Thanks in advance!

I'm working on getting better output from my headlights on my 95 Legacy and the first step is to run some heavier wire to the headlights, and use relays to switch the power through the wires. I have it all wired up in what I think is the right way, but I'm getting some weird results.

 

I have two specific questions:

1) Has Subaru done something weird with the factory wiring that would make a normal relay set up have problems?

 

2) Has anyone done this set up with a similar age Legacy, and how did you do it?

 

Thanks in advance!

Have you cleaned the terrible lenses? All the wiring in the world won't change pitted, hazed, and yellowed lenses.

They're crappy headlights and there isn't much you can do besides cleaning them.

Get the JDM ones if you want good output.

As it has already been stated, the biggest issue with pre 97ish headlights is that they fog up and turn yellow, clean them up and you'll be able to see much better.

 

After that connections get corroded and start to add resistance, clean em up with a wire brush and put some di-electric grease in the plug or deoxit the connectors.

If I had to guess, the "weird" results that you're getting are something like one side comes on but not the other and then, when you switch to high beam, the reverse themselves. In most of the later models, Subaru keeps both filaments hot at all times. If you meter the three wires at the bulb with the lights turned off, they will all meter 12v. The headlight switch sources ground for either the high beam or low beam. Bear this in mind as you wire up your relays.

 

Frankly, though, I think you're barking up the wrong tree here. As the others have said, the first step is to clean the head light lenses. There are a number of ways of accomplishing that. Personally, I use rubbing compound and an old terry cloth towel.

 

After that, if you STILL aren't getting enough light, get a set of the JDM or Euro light assemblies. As I recall, both of those markets still get glass headlights.

 

If, having done all of that, you still don't get enough light, upgrade to a set of HIDs. If that doesn't get you enough light, you need to have your eyes checked.

Dunno about euro ones, but the JDM ones are plastic.

  • Author

Thanks for all the replies to my original post, folks. I know about buffing the haze off the headlights. That's good advice, but not what I am asking here.

 

I am interested in getting full voltage to the headlights, and the stock skinny wiring and crappo connectors are the limiting factor. I am using a relay kit with ceramic connectors purchased from Daniel Stern Lighting, installed with heavy duty wiring. I have installed it as instructed, but not getting the results I expect. Low beams are dim, then when I switch to hi-beam, the lights won't go back to low beam.

 

I am specifically interested in hearing from someone who has succesfully upgraded the headlight wiring, using relays, on a '95 or so Legacy. If you don't have specific knowledge on this, please hold off on your replies.

 

I know some posters have done this wiring mod, so let me hear about how you wired your rig! Thanks, I'll really appreciate it.

  • Author

A quick email to Daniel Stern solved it. I had misunderstood the polarity at the bulbs due the ground-switching nature of Subaru's headlight wiring.

A quick email to Daniel Stern solved it. I had misunderstood the polarity at the bulbs due the ground-switching nature of Subaru's headlight wiring.

 

The negatively switched system throws everyone the first time they deal with it.

I've been contemplating this mod for a while. But I think I'll use the factory relays. They're already wired in. Just need to rewire them with 14 ga wire, or better.

  • 3 weeks later...

use a standard 5 pole 30A SPDT Bosch relay,

 

here is a helpful link

 

I have done this an almost all my cars except the ea82.

  • 9 months later...
  • Author

:headbang:Just wanted to let y'all know that the relays plus HD wiring kit I purchased from Daneil Stern Lighting is the Cat's Pajamas for improving front lighting on my 95 Leg OBW. They throw a lot more light than before the change. The stock headlight wires are tiny thin things, and lose a lot of voltage before getting to the bulbs. I think my lights are brighter now, with stock bulbs, than they were before, with "+50" bulbs.

 

Of course, I keep the plastic lenses polished out, naturally.

 

If you're disappointed in output from your stock Subie headlights, I recommend improving the wiring and adding appropriate relays.

 

Merry Christmas & Happy New Year to my fellow Subie-philes!

  • 9 months later...

I just ordered the kit from danielsternlighting.com along with the bright osram bulbs. I saw the commentary regarding confusion about the "polarity at the bulbs due the ground-switching nature of Subaru's headlight wiring". I am assuming i follow the wiring directions as described in his DIY instructions?

 

relaycircuit.gif

 

thx!

 

addendum - daniel stern replied "Yep -- just use the car's original low-and-common wires to trigger the low beam relay, and the car's original high-and-common wires to trigger the high beam relay, and you'll be fine"

 

and found this in the FAQ:

 

"SPECIAL CONSIDERATIONS FOR GROUND-SWITCHED SYSTEMS

 

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.

 

Now, what are we going to do now that we've used-up our one and only ground wire on the 85 terminal of the low beam relay, but we still have to install the high beam relay? Go to the other side of the car and you have another ground wire! Remember, the relay trigger circuits can be as long as you like, because they take insignificant power. So, you can extend the vehicle's existing headlamp wires to your relay mounting location. It is fine to use this method regardless of whether you have a ground-switched system or not, so go ahead and use it if you're not sure. "

Edited by FleaDog

That diagram will not work with Subaru's switched ground headlamp circuit.

 

Go by his written directions.

Ok, i guess i will try to make the proper schematic and post it up before proceeding.

Competition Limited in Michigan will sell you a wiring harness for your car along with options for higher wattage bulbs. This is a significant improvement but polishing the lenses will help you get the most out of your upgrade.

 

http://competitionlimited.com/ Ignore the HID stuff; sounds good but if the HID is not designed for your reflector and lenses, it's not worth the expense.

I got the $49 rik-2 h4 relay upgrade kit from daniel stern. It has everything you just need (relays, brackets, terminal blocks, terminals, plugs, sockets, fuses and fuseholders) minus the wiring and it's unnassembled versus the option of paying $145 for the same kit all put together. I'd rather save the $$$ buy the wire and do it myself.

 

I also got two osram 70/65w bulbs

Edited by FleaDog

versus the option of paying $145 for the same kit all put together. I'd rather save the $$$ buy the wire and do it myself.

 

I also got two osram 70/65w bulbs

Interesting, I just ordered a fully assembled harness from Competition Limited for my 2002 Impreza for $56 plus shipping. I've bought from them before and have always been pleased with the quality of the product. Also I did order the 80/100w bulbs for it.

I saw the kit that competition limited sells but heres the pic they show on theire site, in actual size:

 

image.jpg

 

And they dont go into any detail about the quality of the parts - i.e. wire gauge, relay brand/materials etc.

 

It looks nice but I want to know all those little detaiils.

Another consideration, higher wattage bulbs give off a lot of heat. Be certain that everyting in proximity to the headlights can stand up to the higher heat.

I saw the kit that competition limited sells but heres the pic they show on theire site, in actual size:

 

image.jpg

 

And they dont go into any detail about the quality of the parts - i.e. wire gauge, relay brand/materials etc.

 

It looks nice but I want to know all those little detaiils.

I just ordered my 4th kit from them; all on different Subarus over the years. The original owner was Gene Henderson who sold to the stage rally population and he was meticulous about the quality of the parts. I doubt Tyler the current owner would cheapen the product when his supplier is still in business. In any event, when I get the new harness I'll inspect it and post brands and such. I know for a fact that the harness has a heavy duty bulb socket to withstand the extra current used by the bulbs. When my first set of higher wattage bulbs melted the socket after a few weeks (didn't have the harness at the time---and I was younger and dumber then too) of use, I ordered the harness. I repair electronics for a living and the wire gauge is definitely sufficient for the extra current draw. The relays and fuse holders are both quality products, but I'll post that as I said.

 

Bottom line is everyone should upgrade the wiring, fuses, sockets and relays if you're installing higher wattage bulbs. It doesn't matter the source of your harness or parts; just do it right. You're better off in the long run with better lighting and safe from burning up the wiring or worse yet, the car.

Red = hot

Red/Blue = low beam ground

Yellow/Blue = high beam ground

subaru used left and right headlight wireing every one else used high and low curcits i take the signal from one headlight to turn on my realays to turn on headlights and wire the power feed right off the post on alt gives me 100amps at 14.50 volts to my 4 100 watt headlights works spanky

Please sign in to comment

You will be able to leave a comment after signing in

Sign In Now

Account

Navigation

Search

Search

Configure browser push notifications

Chrome (Android)
  1. Tap the lock icon next to the address bar.
  2. Tap Permissions → Notifications.
  3. Adjust your preference.
Chrome (Desktop)
  1. Click the padlock icon in the address bar.
  2. Select Site settings.
  3. Find Notifications and adjust your preference.