Well I picked up my JDMs today and started the install. I had previously made the harnesses and thought it would be simple. Well I am sitting here right now with the bumper off of my car and rather angry. It turns out I got the wrong kind of relay for the High/low beam setup with the H4 bulb. Instead of a relay that connects terminal 87a when there is no trigger singnal and then connect 87 when there is I got the relay that connects nothing with no signal and BOTH when there is. This means that both the low and high beam filiment light when the bulbs are on high beam and there is nothing on low beam. I need to go to radio shack and see if I can find a relay that will work.
Not to knock who ever wrote the FAQ and I realize that this method of doing things is on HP.com but they should really speicify the type of relay needed.
Just venting some irritation, guess I'll hop on my bike and pedal my a$$ down to radio shack now.
The problem with that way of doing it is that when you have the high beams on, both the low and high beam filiments are burning. This will eat your bulbs up as they were never designed to both be on at the same time, hence the relay.
Originally posted by Zimmlude The problem with that way of doing it is that when you have the high beams on, both the low and high beam filiments are burning. This will eat your bulbs up as they were never designed to both be on at the same time, hence the relay.
Re-heh-heally? I never thought about that. I just assumed all H4's worked like that? So a regular H4 in a civic only runs one filament at a time?
Well that is how they work. The reason they put both filiments in one bulb is because it consolidates both high and low beams into one bulb. They are not designed to run with both on as the inside of the bulb would get very hot. The high beam lights up what the low beam did and adds to to it.
Anyway I went out and found the correct relay and it works great now. One question, why would wiring the bulb in the way described by SRV inhibit the fogs from being used. Just run a new relayed circuit from a switch inside the car to the lights just like a regular set of fogs. I went out and bought an aftermarket foglight wiring kit and that is what I used to power the fogs, works great.
Originally posted by Zimmlude Anyway I went out and found the correct relay and it works great now. One question, why would wiring the bulb in the way described by SRV inhibit the fogs from being used. Just run a new relayed circuit from a switch inside the car to the lights just like a regular set of fogs. I went out and bought an aftermarket foglight wiring kit and that is what I used to power the fogs, works great.
The way I did it does not prevent you from wiring the fog lights, I'm just to lazy to do it...
I can't imagine that the low+high is that much hotter than just high, but it's hotter regardless....I'll look into fixing that...but again, the laziness factor kicks in...
Civic headlight bulbs are directional. They have a top and a bottom and they only fit into the headlight housing one way.
If you look real close at the bulb, there is a little piece of metal in between the 2 filiments acting as a shield. When the low beam is on, the light mostly shines out on the bottom side of the bulb and hits a certain part of the reflector in the housing that directs the light down and to the right so as to light the road, but not blind traffic. When the high beam is on, the light comes out of the top side of the bulb and the reflector directs the light up and to the left and right to light a dark road.
The high beam filiment is a little brighter because it has the disperse light over a larger area whereas the low beam is somewhat concentrated.
Hope that makes sense.
You shouldnt run both the high and low beam at the same time in a dual filiment bulb because you caould overheat the bulb and have it explode in the housing, and thats not pretty.
Zimmerlude is correct, Awhile back i helped my friend install jdm's, we just connected low to the low and the higt to the high. After hitting the high beams a couple times, the blub went out, when i looked at it, the ground wire was fried/melted, the blub was still fine : ). What i think happened was that there was too much current going though the wire when both the high and low beams were on. The relay alleviates this problem by only allowing either the low or high beam to work
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