[gregotis]

O.K. Im lost! I have 71 240Z and want to wire in relays for H4's, but can't seem to get it through my fat head.Here's what I think I know, each headlight has a seperate fuse, the right headlight power wire is red, the left headlight power red/yellow. The red/black wire and red/white wire are common ground wires one for low one for high beam?
Each relay has four terminals on it. (Left headlight for example). #30 power from alt.or battery,#86 red/yellow low beam from switch, #87 red/yellow low beam to headlight, #85 to ground on chassis. What is power in and out for high beam?
I don't know if I'm dumb and lost or any where near on track but this is getting old! Please help me by giving me the idiot step by step process for the whole thing if possible?

PLEASE HELP,
Greg

 

[ConorP]

You describe the system fairly accurately. The combination switch supplies power to both headlight fuses, this switched +12 then feeds each headlight seperately. Red for Right, Red w/ Yellow for Left. Both headlights high beam connections are common, and both low beam connections are common. Then either the low beams are connected to ground through the high/low switch, or the high beams. So turning the headlights ON applies power, but high/low depends on which filaments are connected to ground.

So how do you wire them? For 2 relays you need to retain the original Red w/ White and Red w/ Black (high/low) connections and only use the relays to switch +12 into the bulb side Red and Red w/ Yellow.
(Standard Bosch Numbering)
#85 to switched side Red (Red w/ Yellow)
#86 to Chassis Ground
#87 to New +12 Supply (battery/alt)
#30 to bulb side Red (Red w/ Yellow)
#87a Not used

However this setup will still use the original wiring for the high/low beam select. If you want to elimate this you would need to use 2 relays on each side. I believe this is how the "Painless Wiring" headlight relay kit works.

ConorP