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This whole headlight relay thing.....


rydsno
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OK, so i went down to the parts store today, got some relays, some 12 gauge wire, fuse holders and fuses. I spent about 4 hours messing around, making nice wiring harnesses, getting everything all set up. Ran 12 gauge wire right into the bulb sockets. Hooked them up, turned them on with great anticipation and excitement, aaaaannnnnndddddd.........not impressed. My stock wiring was brighter. Checked my grounds, checked my voltage. 12.20v to the stock lighting harness, 12.08v to the new, "heavy duty" 12 gauge harness. I even ran power direct from the battery to the headlight, and still not better. I'm pretty disappointed with the mod. I put it back to stock. Maybe someone can enlighten me, but i'm leaving them stock now. Just gonna buy nice fog/driving lights. Needless to say, i'm not recommending this mod....yet.

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How did you hook the relays to the battery? Where did you mount the relays? There should definitely be the same or even more voltage at the headlight using a relay. Did you check the voltage going into the relay and out of it?

 

The whole purpose of using relays is to cut down the distance the electric needs to flow from the battery to the lights, this applies pretty much to anything you use a relay for, especially with aftermarket lights, in the "old" days aftermarket lights only came with a switch, a very heavy duty switch I may add usually a 20 or more amp rated switch and when the lights were hooked up, power had to go from the battery to the switch in the cab than back out to the lights, a big waste of voltage.

 

Newer lights and this headlight mod using a relay is designed so the power goes the shortest distance from the battery to the lights, in this case of the headlights, (sorry if this is how you did this I'm just saying how I would do it and how it should be done), Anyway, The relays should be mounted as close to the battery as you can, run a heavy wire, with a fuse, from the positive on the battery to the "30" tab on each relay, than I would run the same gauge wire from the output of the relays, the # 87 position to one terminal on the headlight, I would than run a wire from that wire across to the other headlight, The ground wire should be the same size as the positive wire you use. The thing with relays is the trigger wire, the wire that turns the relay on can be very small as it only carries small amperage, which when aftermarket companies started including relays in their light kits the switches were able to become smaller and a lot less amp rated. The trigger wire would be the stock headlight wire for the low beam and for the second relay the high beam.

 

Another thing people doing this mod can do is to purchase a double relay (2 relays in one), some use a common power in terminal for both relays some do not, Hella and if they are still available Dick Cepek make double relays.

 

Let me know how you did yours,

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The stock wiring will provide pretty much the same voltage, assuming it's not loaded. The problem is that it (and the contacts in the headlight switch) can't pass full current to run the lights. If you're measuring without the bulbs, you're not getting useful numbers. If you are, well, I'm confused. Either way, your harness still shouldn't have more resistance then the stock spaghetti wires.

 

What's the rating on the relays? And where did you hook in your + lead and ground? (I hooked my ground to the engine bay, and the + direct to the battery clamp.)

 

Also: when I did mine, one light was really dim. After going over my connections, I realized the headlight plug was just loose. When I pulled on the plug, it took part of the back of the headlight assembly with it. Once I got it seated right (threading the little contacts back through), it worked properly. I doubt this is your problem, but it can't hurt to check.

 

Pics would help!

Edited by Slartibartfast
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Here's what i did......

 

(batt+) ---> (12g wire) ---> (25a fuse) ---> (50a relay) ----> (low beam).

 

stock low beam wire --> relay

 

relay --> ground

 

 

 

I even tried.........

 

(batt +) ---> (12g wire) -----> low beam

lamp ground -----> (batt-) / (chassis-)

 

The run of wire to the headlight was only about 30" long. In both scenarios, even direct from the batt to the lamp, it wasn't brighter.

I tried using batt- and chassis ground, no difference. I'm quite familiar with electricity and electronics, i work on low voltage systems(fire alarms) for a living. I understand the concept of line loss and amp draw, etc. The only things i can come up with are a- crappy relays or b- crappy headlight sockets. I even went to the extent of removing the connectors from the headlight socket and soldering the 12 gauge wire right onto them. I find it strange that even direct from the battery, I get no increase.

 

And i don't have any pics, cause i pulled everything back out:)

Edited by rydsno
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Clearly then you understand the electronics better than I do. :)

 

What bulbs are you running? I imagine the mod would have a greater effect on higher-amp bulbs... still doesn't explain how the voltage could be lower.

Edited by Slartibartfast
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You could always buy the clear ebay headlights and install projectors with hids like I did it was easy and they are the brightest headlights of any car i have ever sat in.

 

 

here was my write up....costs about 200$ though but best mod I did to the truck.

http://www.nissanpathfinders.net/forum/index.php?showtopic=31473

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Sorry I went into so much detail, was not aware of your back ground, just covering all the bases so to speak, I can't see how running a wire from the battery directly to the headlight bulb would have less voltage showing than going thru the stock setup, baffling me as well.

 

I will say without doing any electrical mods I installed a pair of those Silverstar Ultra bulbs in my Sentra and they made a big difference, nice thing about my Sentra (1990) is it has glass lenses so no yellowing, can't recall are the stock PF headlights glass? I swapped mine out to the hardbody style and have normal sealed beam headlights for now and they are a lot brighter than the stock PF one's were.

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I will say without doing any electrical mods I installed a pair of those Silverstar Ultra bulbs in my Sentra and they made a big difference

Silverstar Ultras have blue tint on the glass, which reduces usable light output. All the blue tint does is filter out all of the blue light. Read here for more info.

Edited by Towncivilian
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Sorry I went into so much detail, was not aware of your back ground, just covering all the bases so to speak, I can't see how running a wire from the battery directly to the headlight bulb would have less voltage showing than going thru the stock setup, baffling me as well.

 

I will say without doing any electrical mods I installed a pair of those Silverstar Ultra bulbs in my Sentra and they made a big difference, nice thing about my Sentra (1990) is it has glass lenses so no yellowing, can't recall are the stock PF headlights glass? I swapped mine out to the hardbody style and have normal sealed beam headlights for now and they are a lot brighter than the stock PF one's were.

 

No problem at all, I wasn't meaning to sound like a smart a$$ :).

I definitely appreciate you input, that's what i'm looking for. Even though I work with electrical stuff, a lot of people here have waaay more experience with pathfinders than I do. Sometimes there are little tricks that people have learned over the years that help out a lot.

 

One idea is that this mod would be a lot more beneficial if you were running higher output lights, but mine are pretty close to stock wattage. I have silverstar lights as well. So, I dunno, i'm thinking of trying to find the clear lens headlights and running good bulbs instead. I read that the clear lenses with a good set of PIAA bulbs is awesome and as long as you don't oversize the bulbs, you don't have to upgrade the wires.

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Also. The MAJOR problem with the Pathfinder "sad eye" headlight, isn't the wiring... or the housing... it's the 9004 bulb. the bulb just sucks. It's a huge fail. I'm fairly certain the stock low beam wattage on those things are 45 watts? What the frick??

 

You really want to take care of the problem? Get the buckets from a hard body pick up, the headlight pigtails, the grill, you can use PF marker lights, but the pickup markers go with the pickup grill better, get some Euro H4 housings. and a decent H4 bulb. splicing the headlight plug is cake, the wiring is the same color. And you're done! You can see for days!

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No, it is the wiring. It doesn't have enough meat to transfer the entire 45 watts into the bulb. Remember 45 watts at 13+v will also be a hell of a lot brighter than 45 watts at 12v but it will need fatter wiring to transfer all that power. Then you need to aim the headlights properly.

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Tungsten, it still doesn't fix the fact that the 9004 bulb is garbage.

Of course it sucks compared to a higher wattage bulb but it's not worth to replace the OEM housing with some cheap plastic e-bay junk just to use a better bulb.

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Sure, you can use sealed beam sized headlights with H4s as long as they're not crappy plastic. I think that's what silverton was getting at. That's not out of the question but it purely depends on your tastes and preferences. Personally, I don't like the look of a Hardbody grille with the buckets and sealed beams. The "sad eye" headlamps are my favorite design. What I rather do is add more auxiliary lights to increase the visibility at night. Running fog lights at night creates a big improvement too because they cast light where the headlights do not.

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I never said to use plastic headlights. That's retarded. There are quite a few glass/quartz options on the market for the 200mm headlight size.

 

I have owned several vehicles with 9004 headlights, and they have all had terrible light output, polishing a turd doesn't make it look or smell any better.

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