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Hi

Building an MX5 based clubman. Using loom from 2002 NB which has separate headlight globes for low and high beam. How do I wire this up to a 3 pin H4 halogen single globe inside one headlight and use the stock switch to get low and high beam to work?

Please keep any replies simple - electrics are not my forte.

cheers

Mark

All you would need is a test light, a connector that fits onto the H4 or you could get away with a few terminal connectors (decent female blade ones) and maybe a bit extra wire if the original wires won't reach.

Find yourself a wiring diagram and find out what wires are power/earth and cut and connect to the H4 accordingly.

Or...Is the rest of the wiring loom installed? If it is you can leave the old headlight plugs off and do it this way.
All you need to do is go to the 2 plugs you have now for high and low and test which wires have power and which wires have earth. Test both plugs while having them both switched to high and low. Note down your findings so you don't get confused! Once you know what wires have power or earth you can cut and connect them upto your H4.

Can't remember what pins on the back of the H4 globe need power or earth to work properly. Maybe a quick google could help. Or trial and error guessing?

Pretty sure this will work although I know some manufacturers do funny things with their high/low beam circuits, like switching power wires to earth supplies. So not 100% sure.

Also may have to do something with the fuses/relays but I doubt it.

If anyone else reads this and thinks I'm wrong please tell me because I would like to know haha!

Divo wrote:Hi

Building an MX5 based clubman. Using loom from 2002 NB which has separate headlight globes for low and high beam. How do I wire this up to a 3 pin H4 halogen single globe inside one headlight and use the stock switch to get low and high beam to work?

Please keep any replies simple - electrics are not my forte.

cheers

Mark

in the 2002 wiring there are two fuses that run the left and right head lights these go to the common pin in the pic above
the switch on the column turns on earth so you could run these wires to the high low pins BUT when you switch to high beam
you get both elements of the bulb on.
to fix this you need a change over relay (left) and a STD relay (right)


Right now we have to wire this up I'll use CO as change over and STD as standard
connect 30 co to 87 std
connect 85 co & 85 std to batery via fuse
connect 30 std to Earth
connect 86 std to low beam earth from switch
connect 87a co to low beam pin on H4
connect 87 co to high beam pin on H4
connect 86 co to high beam earth from switch
now the H4 Head light will switch element when switching from low to high
well thats how i did it to our LOCOST 7

Thanks Russell

All is a goer now thanks to your guidance.

cheers

mark