Wireing up H4's correctly

[Dave84]

I want to put my H4s back in but i want to wire them up thr wright way so my high beems arnt always on and, wondering how to wire in the relays so i dont burn up the wireing.
Thanks

[MasterBlaster]

I have some fairly-easy to follow diagrams in my collection.
Use at least 12-gauge, or even 10 if you have a spool lying around.
Thicker wire = less voltage drop = brighter lights.
These diagrams don't show it, but put some big inline fuses (20-30A?) in each power wire (red) fairly close to the battery, just in case something rubs through, or a relay comes unplugged (sparky-spark).
.

[1987cp]

Cool, useful info. I'll have to refer back to this at some point.

[Dave84]

thank's i appreaciate it

[MasterBlaster]

Almost forgot the other stashed pic.
Here's the general layout, just imagine a couple more plugs (for the hi-beams), and maybe a couple more relays.

[MasterBlaster]

Aaaaaaand (there's always an "and")......

Don't forget the pinning on the H4 bulb is not the same as your "normal" 4656 headlight. You'll either need to use adapters, or remember to rotate your wires one pin clockwise when building your harness.

[85crownHPP]

that wiring difference would explain Daves high beams... also now I remeber Nathawks acting funny when he put one of his in.

PS.... if you use SPDT relays like the ones shown in MB's pics, you can power some fog lamps from the unused output of the high beam relay. Thise output stays on untill the relay is triggered (you turn the high beams on) then the output is switched from the fog lights to the high beams - the end affect is your fog lights go off when your high beams come on (the way they are supposed to work)

[FordInPossession]

All I did was take the terminals out of the factory plug and put the in the right places to make the H-4's work. Not that hard. Wire probe to find which terminals work with low beam, then high beam. Look into the H4 and you can see which terminal goes to ground (Hint it goes to BOTH filiments) and start there. THe low beam is usually the smaller filiment. Takes maybe 15 minutes if you can test and trace wiring. No need for harnesses or adapters or anything like that.

[Archangel]

PS.... if you use SPDT relays like the ones shown in MB's pics, you can power some fog lamps from the unused output of the high beam relay. Thise output stays on untill the relay is triggered (you turn the high beams on) then the output is switched from the fog lights to the high beams - the end affect is your fog lights go off when your high beams come on (the way they are supposed to work)

Or, you can do like me and wire up the fog lights to the markers and the low beams, this way the fogs come on with the markers, go off with the low beams, and come back on with the highs - sure the fogs ain't supposed to stay on with the highs, but they do make a positive difference in the light spread pattern.

[CheeseSteakJim]

Wait, so what are H4's exactly?

[MasterBlaster]

Basically, when we say "H4", we mean a two-piece headlight. Housing + replaceable bulb (wattages from 60/55W up to 130/100W). The housing is usually made to European "e-code" specs, with full light on the road, and a sharp "cutoff" line above a certain height, instead of the shapeless blob of pathetic "light" stock DOT sealed beams give.

Pictures of various housings, bulbs, a little history, etc.
http://www.danielsternlighting.com/p.../products.html

Google "image" search.
http://images.google.ca/images?hl=en...+pattern&gbv=2

A picture of the housing is above, in my Aaaaaaaaand posting.
Here's the pattern and the bulb:

[P72Ford]

This is good stuff... I was wondering why my high beams were on all the time. Appreciate the info!

[1987cp]

Peculiar. What's with the asymmetrical dispersion pattern?

[MasterBlaster]

You mean the slight variation in the left and right-side patterns that are just the result of a bad drawing, or the diagonal upsweep on the right side that helps light up roadside signs, while still keeping the light out of the eyes of oncoming and followed drivers? In right-hand-drive countries (UK, etc.), the upsweep is on the left side.

[1987cp]

Ah, light up road signs. That would make some sense. Still suck to drive to the right of a vehicle so equipped, though ... maybe that's why I find it so awful to cruise in the right-hand lane at night.