Headlights Wiring Upgrade

[NachaLuva]

A while ago I upgraded my lights from from dim to dazzling!

I thought I might share how I did it. There is no cutting of factory wiring by the way.

First, the schematic:




Note Subaru wiring is "positive switched", ie, the current goes from the battery to the lights then to the switch on the lights stalk. I know this is counter intuitive, it should be called "negative switched" as its the negative earth that runs through the switch, but this is what all the literature calls it

The lights relays are connected to the battery positive via the battery relay. As the lights are switched on, it switches the factory relay to supply positive to the lights connector, which I have used to switch the battery relay. This then provides the positive to the low and high beam relays.

From the diagram, follow the original wiring from the original headlight socket. These wires are controlled by the switch in the light stalk on your dash. Remember these are earth wires. As one or the other is switched, it provides a ground for the relay to switch on.

I did the driving lights relay at the same time so it would be neater. It is controlled by a wire going from the high beam relay (switching side) to the dash swich, then back to the DL relay. The DL switch is wired with a little indicator light. Unfortunately, because of the way its wired, the indicator light is always on if the switch is on plus the lights are on, whether its high or low beam. However, the relay only switches on with high beam. Its a weird peculiarity lol

Note that the DL are wired conventionally, ie, positive is fed from the battery relay to the DL relay to the lights then earth. Unlike the headlights which are battery relay to the lights then to high or low beam relay then earth. I did this as I always planned on using HID driving lights and I think (?) they need conventional switching.

Wiring layout diagram:



Lights socket connector:

 

[NachaLuva]

The wiring loom I made:

Fitted into the (dirty, lol) engine bay:

Connecting the connector:

These are the wires that control the relays. When you turn on low beam or high beam, they are fed current from the headlight connector and switch the appropriate relay.

The new lights connector:

I got these from Bright Lights Auto Parts:
https://myworld.ebay.com.au/brightlightautoparts/&_trksid=p3984.m1439.l2754
They are ceramic and wont melt.

The switch for the driving lights:

Got this from Repco, was a near perfect fit in the factory cutout

 

[NachaLuva]

I originally got 130/90W 6000K bulbs but they were crap! they looked cool but a few birthday candles lit the road better!

So then I got some 130/90W bulbs from https://myworld.ebay.com.au/blingwork_automotive_lighting/&_trksid=p3984.m1439.l2754Ringwood Automotive Parts: https://myworld.ebay.com.au/blingwork_automotive_lighting/&_trksid=p3984.m1439.l2754
nrap

These were good but I wasnt satisfied! I also got some Phillips Rally globes from blingwork_automotive_lighting

These are outstanding!!!

Finally, I very carefully adjusted the aim so I wouldnt blind oncoming traffic or draw unwanted attention from my mates in blue :iconwink:

 

[NachaLuva]

I used very heavy wiring (12 guage) from Jaycar for the lights and thin wire (3mm) from Autobarn for the control wires. All relays are Narva 40A resistor relays with twin 87 plugs. I got heat shrink tubing and that split tubing from Jaycar and used quality Japanese elec tape, so it wouldnt unroll. Fuses are waterproof 30A, from Repco I think.

The relays and fuses:


Hope all this helps. I know I was VERY confused at first, but with some help I slowly figured it out.

Clear as mud?
Please ask and I'll try to help...

 

[mr turbo]

Great write up Nachaluva :ebiggrin:

Well done mate

Regards
Mr Turbo

 

[Dedman]

After almost collecting a kangaroo on my last trip I decided it really was time to do something about my lights. I upgraded my wiring the using NachaLuvas guide but did wiring a little differently with the new globes having a common negative and switching the high and low beam positive supply. Also I don’t have any driving light stuff in there. Here is my more simplistic wiring diagram (don’t have the skills/software that NachaLuva has when it comes to making pretty diagrams but you get the idea and hopefully the simplicity will be easier for less electrically minded people to follow.)

I ran the wiring to the driver side globe just behind the grill as it was the shortest route so less voltage drop. Also mounted the relays just above the battery to keep wire length to a minimum (mainly because I didn’t have that much wire…:rotfl

I used a couple of 40A relays with sockets and also ceramic headlight connectors (had a melting connectors on a motorcycle once and I'm never doing that again…)

My new globes haven’t arrived yet but already I can see a difference in brightness (stock wires are stupidly tiny) and with my new high wattage globes I’m hoping for the finished product to be like day.

 

[taza]

Great to hear mate, I might go down this route soon. Could do with just abit more light even with my lightforce 170's..

 

[NachaLuva]

This looks fine, not sure why you're getting a voltage drop. Perhaps check the earth connections (usual culprits), also did you use double 87 relays or double up the wire in a single connector? I used double 87 relays also soldered all connections. I wanted to be certain there was no voltage drop also complete reliability as I have once had the lights switch off in an old car on a windy country dirt road at night....a pants changing moment! :rotfl:

 

[PigSti]

Is there a way of just reinforcing the existing harness to over come the dreaded voltage drop without a complete new loom?

 

[Dedman]

did you use double 87 relays or double up the wire in a single connector?

Used just single 87 but shouldn't be an issue I think some of the wires might just be a tad thin (teach me for being lazy and just using what I had lying around....). I'm thinking that I might redo it when i get a chance using heavier wires throughout and also complete separate circuits for high and low beam with separate fuses so there is a backup if one blows.

Is there a way of just reinforcing the existing harness to over come the dreaded voltage drop without a complete new loom?

I would say it would be far far more complicated than just making a second loom as NachaLuva and I have and the plus side with a second loom is that if it fails you can just plug the old one in to get you home.

 

[NachaLuva]

I'm thinking that I might redo it when i get a chance using heavier wires throughout and also complete separate circuits for high and low beam with separate fuses so there is a backup if one blows.

Cant remember the gauge of the wire but its very thick!

I considered separate circuits with separate fuses a must as if the fuse blows on one you can quickly switch to the other while you brake :iconwink:

with a second loom is that if it fails you can just plug the old one in to get you home.

Exactly...this way the OEM loom is totally untouched & ready to plug back in :biggrin:

You can also get this loom premade on eBay, Venom did this & it looks well made with no issues AFAIK...just plug & play :biggrin:

 

[idw]

12.5v @ 30amps over 2.5m (so battery round firewall to other headlight) with 10mm2 (7AWG) has a voltage drop of 2% so 12.2v at the light. That size should be safest (or go bigger but thats just making the wire more expensive and harder to crimp and terminate, really isnt any need to) as the fuse will blow before melting if your using the same gauge fuse housing (thats the important bit).

Thats best case anyway 7 awg will take 70-80amp.

Double voltage drop for ally wire.

But it all depends on the globes as well 100/80 h4 globes use 8.5amps when at full power (12/100 = 8.3amps) so over 2.5 metres on 5mm2 at 15amps (11 or 10 awg) wire still only 2% drop in voltage

So if your fusing right next to the battery (as you should) anything from 5mm2 up to what you can realisticly fit in the connector will show a huge improvment in output.

And for extra's assuming a rc of 90 if you leave your lights on its about 5 hours till the batterys dead and 1.5-2 hours till it wont start the car.

 

[Sarge98]

Nice work. The headlights are terrible so an upgrade is a good investment! Switch panel looks exactly like mine (even got the same switch) but mines for the lightbar.

 

[Dedman]

I considered separate circuits with separate fuses a must as if the fuse blows on one you can quickly switch to the other while you brake :iconwink:

Looking at your circuit diagram the high and low beam are on the same circuit with only one fuse.....

Also I have redone my wiring today with whopping 8gauge wire and now there is only 0.3v voltage drop when measured across the globe terminals. :ebiggrin: Cant wait to see if there is a big difference when I try it out tonight.

Nachaluva did you ever measure the voltage drop on your globes? I would be curious to see hear what it is with 12gauge wire and the longer run you have compared to the 8gauge. Those phillips rally globes sure do suck the juice. Not sure how much because I can only measure up to 20A but definitely more than that for 2 of them.......

 

[PigSti]

Here is my loom update for my OEM Reflector STi HID install. I thought if I'm going to do this I would finally install the HID.

I took your advice to leave the original loom in place in case I have to go back to it!

 

[Ratbag]

Gidday NL

Does the SF have glass headlight lenses? Rear shell?

SG (MkII, not sure about the MkI - 2003 to 2005) and onwards have polycarbonate ("plastic" ... ) headlight lenses, so can melt bits if the wattage goes too high.

They also have what is a weird setup to me, where the low beam lights are non-dipping. Or dipped all the time, I should say. Both high and low beam are single element globes. Is this the norm in modern cars?

IMO, humans finally got car lights right with the Austin Kimberley in the early 1970s with 4 separately adjustable square headlights. These ran 75/55W dippers in the outer pair and 75W in the inner pair. Our 1993 Camry had a very similar setup. Both had superb lights as standard ex-factory, with 300W of non-dipped output - 4x 75W.

Ex-factory, my Impreza lights were borderline acceptable - 60/55W, single reflector. The factory bulbs fried the non-thermoset plastic connectors. I replaced these with thermoset plastic ones and never had another problem with them. After that, I ran 90/55W bulbs, and these were OK, but nothing flash. We did a huge amount of night driving with these lights, but I was never really happy with them (compared to my old Kimberley and our then current 1994 Camry).

Wondering what remedies are available to fix these lights, or whether it is cheaper and simpler to fit decent driving lights one with a wider beam, and the other with a pencil beam. IME, once they get beyond the reach of normal headlights, these sorts of lights tend to throw sufficient light around the countryside even when only a single light of each kind. I have used 100W light aircraft landing lights to good effect in the distant past ...

 

[idw]

Ratbag, Is the outer lense plastic or glass? my old fords lights were poly, 2000 wet/dry and some toothpaste polished the hell out of them and they ended up far better after that. My SF headlights improved simply by ditching the headlight protectors and spending the time aiming them at the back of the shed, bit of ply with and x on it helps there too. I've also got lightforce 170's on the front with a pencil and spread beam, so theres more light comming out of the front of my foz then most.

 

[Ratbag]

Gidday Id

The "glass" lens is polycarbonate. The rear shell is some kind of plastic.

Thanks for the fantastic suggestion about the toothpaste :biggrin:.
I use toothpaste for cleaning lots of stuff, but it had never even crossed my mind to use it to clean up the UV deterioration of the D/S "eyebrow" (where the parking light is on the SG MkII). Worked an absolute treat, and it didn't cost 'only' $36 for the tube (already had some in the bathroom cupboard) ...

I have always thought that the P/S front of my S/H Fox had had some kind of minor bingle because the headlight assembly on that side is brand new. While cleaning it, I found a tiny patch of overspray on it, so confirmed my suspicion. There was never the slightest indication that the damage was more than slight, just the newer headlight and the paint is the very slightest different colour on that mudguard. One swatch different on a full Pantone chart is all :iconwink:.

How have you mounted/wired your driving lights?

 

[idw]

I cut a piece of 4mm angle and screwed it behind the SF nudge bar, mounted lights on that, I would of made a loom but the lights and loom were a 21st present a few years ago.

The mount has a little flutter as i forgot to screw the bottom of the angle, been meaning to fix it buy my girflriend nicely reversed into the front of my foz an now the nudge bar doesnt come off.

Anyone else wanting to polish the lights dont use anything courser than 2000 you'll never get the scratches out again!

Also if anyone is changing the globe reciever make sure the new ones installed to be waterproof mousiture and oils blow hella globes in a fraction of a second. Made that mistake changing a stage light had it blow glass into my arm when it was being aimed.

Has anyone done a before and after photo of the light output before ad after putting the loom in? Would be great for those thinking about the upgrade

 

[Ratbag]

I can see that having a nudge bar is sort of essential, given the shape of the SG MkII Fox, and the cost of driving lights these days ...

Either that, or spend one's life worrying about the safety of one's expensive spotties ...

I can see a piece of aluminium box section running across the front of the car near the bottom of the grill. It looks to be strong enough to mount a light bar onto, as long as the lights are protected by a nudge bar. I'm not sure what's inside the flaming thing though! The front of these cars is bristling with all kinds of crash sensors, so it pays to be really careful IMO.

I don't like the idea of attaching a light bar to the number plate mounting points. Seems to me that such a fixture would make it all too easy to steal the bar, lights and all! It is also far too far forward on the vehicle, putting the lights in constant danger from careless parking, amongst other risks.

What do you think of the Lightforce 140s? I can see that the maximum bulb is 75W, but this may well be sufficient with one pencil filter and one half pencil filter. They appear to be far smaller than the 170s, so could well tuck in better on the SG MkII. Bear in mind that I avoid doing a lot of night driving these days.

The ex-factory lights on the SG MkII are not all that bad (55W lows and 60W highs, giving good spread from the lows and pretty good distance from the highs), they just seem to fall to ground level a bit closer than I would like for open road driving. If they were independently adjustable, they could probably be made to work better ...

Perhaps if I can get the existing lights better adjusted, they will be sufficient.