Mister.E

i searched the boards and couldnt find an answer to this question so hopefully somebody knows.

i converted my 180 to a silvia front end and i have a question about wiring the bricks. me and a buddy found the switched +12VDC on the old pop-up motor harness that sends voltage to the headlight motor when the headlights are turned on or when you press the headlight pop-up button. what i want to do is use those 2 wires to run 12VDC to the inner H3C bulbs on the bricks. basically what im trying to do is have the H4 lamps and the H3C lamps all turn on when the headlights are turned on. the reason that i dont want to wire them into the H4 low beam signal is because when i flick the H4's to high beam i want the H3C's to still be on acting as a low beam, that way i have a sort of dual beam light output when driving in really dark low lit areas. what im wondering is can the wiring that was previously used for activating the motors supply enough current for the H3C bulbs without failing in one way or another?

__________________
: @e_lemonation

g6civcx

Questions:

1) How many Watts does each bulb you want to use consume? You can read the label on the box or the bulb itself. Usualy headlight bulbs are around 30-50W.

2) How thick, i.e. what gauge in AWG, is the wire you want to use?


3) This doesn't make sense:

What do you want to do?

Answer this question like this:

Which light(s) do you want to be on for the following headlight combo switch positions?

Headlights switch off
Headlights on parking
Headlights on low beam
Headlights on high beam

Mister.E

1.) all of the H3C bulbs ive seen around at local stores are 55 watts and the Raybrigs i have been looking at are rated at 55 watts

2.) ill have to check on the AWG of the wire. the wires running to the headlight motor harness appear to be the same exact size as those which are used for the stock H4 bulb harness so it should be ok....

3.) sorry about the confusing wording

Headlights switched off -> nothing on
Headlight switch on parking -> only parking lamps on
Headlight switch on low beam -> H4 bulbs on low and H3C bulbs on low
Headlight switch on high beam -> H4 bulbs on high and H3C bulbs on low

i have already purchased H3C harnesses from a local store off base and the wiring seems to match up to the size of the headlight motor wiring. im sure what im getting at will work but i dont know how much current the motor wiring is actually rated for and i dont want to possibly fuck it up by wiring in these headlights. this modification is obviously not necessary but it would be a hell of a lot better for me at night if it was possible. thanks.

__________________
: @e_lemonation

g6civcx

This is not going to work with the stock S13 headlight wiring for these reasons:

a) you're pulling 2 H4s and 2 H3C on low. The headlight on each side is only rated for 15A from the factory.

Power / Voltage = Current

55W / 12 V= 4.6A nominal, with 15A max

The stock headlight gives low or high on each side, but not both.

When you're using both h4 and h3c on the same line, you'll get double the rated current

2 X 55W / 12V = 9.2A nominal, with 30A max

This is getting close to maxing out the wire and (you hope) blowing the fuse or maybe fire.

Same rationale applies on hi beam, and will be worse because h4 hi draws more current


b) there is no way to make the h3c work the way you want with the stock wiring. You have to use relays, diodes, or some other rewiring.

The reason is because the light combo switch acts like a diverter. Current is diverted between nothing, lo beam bulb, and hi beam bulb. There's no way to make the h3c stay on with the lo and hi without tying both the low and hi beams together = all h4 lo/hi and h3c will be on all the time regardless of the combo switch being on hi or lo.

The only safe way to do this is to use relays and run separate power wires.


Now take what I said with a grain of salt. I have not played with a JDM headlight wire harness so my comments are based on USDM wiring.

Do you want to do this? Do you mind if the H3C flicker on and off and back on realy quick when you switch from lo to high and from hi to lo?

Mister.E

thanks for the advice. im not sure if we are on the same page though. in your description it seems like you are thinking i am trying to wire the H3C's into the H4 harness. this is not the case. i am trying to wire the H3C's into the no longer used pop-up motor harness because once the headlights are switched on the motor harness receives a constant +12VDC, which in theory should be able to power the headlights. i will NOT be wiring any new bulbs into a headlight harness that is already being used. since i do not have the pop-up font anymore the old headlight motor harness is a free source of voltage, i just want to know if each motor harness can handle the current that 1 H3C 55watt bulb will draw. the motor circuit i would be using already has relays and everything else to make it complete. if i am totally misunderstanding what you are saying then i apologize.

__________________
: @e_lemonation

g6civcx

This is ok. In fact, that's how I had my H3C wired.

I had mine wired up to the retractor switch to turn the h3c on and off independently on the headlights.

Will that work for you? You would use the retractor switch to turn on and off the H3c bulbs. The combo light switch controls the h4.

Or do you want the combo light switch to turn the h3c on whenever it's on lo beam or hi beam?


That's doable if you H3C bulbs don't pull too much current.

Mister.E

ok thats basically what i was getting at. its hard to explain shit through typing but i think we are on the same page now. the two wires that i found on the pop-up motor harness actually get +12VDC when you flip the retractor switch or turn the headlight switch to on. so if you had yours wired up in a similar fashion i dont think that the lamps are going to draw too much amperage from the circuit. thanks for the help man!

__________________
: @e_lemonation

g6civcx

That'll work. If you want the H3C bulbs to be on with headlights or retractor switch, then just leave it as is. It'll work.

Otherwise, if you want to control the H3C bulbs with the retractor switch regardless of the headlight switch, then remove the retractor relays 1-4, and you have to bridge together I believe relays 3 and 4.

If not then don't bother. It'll work like you want.

Mister.E

good shit. i really do appreciate all of the help

__________________
: @e_lemonation