headlight wiring help

[mitchy]

ok on my 31, i think the standard non-projector headlights use a H4 or similar bulb, whereas my projectors run a small loom off the H4 plug to adapt to the H3C globe.

now on the H4 plug, 1 wire is constant 12v (even with ignition off) and then there are 2 grounds, one for high beam, for for low beam. the H3C bulb is simply positive and negative, so it would go off the low beam negatively switched wire and constant 12v.

when i switch my high beams on, the low beam goes off, i want to make up a new loom that keeps the low beam on with the high beam.

is it simply a matter of running the negative for the globe to both the high and low negative wires (ie, running the black wire in the below picture to both the pin its currently attached too, and to the pin that has no wire attached) or does it not work like that?

http://i287.photobucket.com/albums/ll145/mitchyvr4/100_2807.jpg

[hako]

That will work, you run the risk of burning out your headlight switch though as you have suddenly added ~10amps to the high beam circuit.
Won't happen immediately, but in a few months/weeks you may find you have no high beam.

[mitchy]

is there another way to do it then?

i was thinking of running a relay anyway, as apparently the 31's run the power through the headlight stalk, and they burn out.
would i need to run a relay for each headlight, and each circuit, so 4 all up?

[hako]

Yep, most nissans of that era (patrols, skylines, pulsars etc) burn out the contacts in the headlight switch.
As for how many relays you need, it's best just to work out the load on low beam and high beam. I assume low beam is 2x 55w globes? so that is about 10amps at 12v, so 1x 30amp relay would do both low beam globes.
If high beam is double that, a 30amp relay is still sufficient (as voltage increases to 14volts the current load decreases).
Personally if it was my car and I was going to do it i would just put relays on high beam circuit, (not worry about low beam) and use 1 relay per side. (I like redundancy in things like that).

[mitchy]

low beam are being converted to HID too, so i think they are only ~35W each.

i'll just run the relay on each high beam circuit as you suggested, cheers!