sti+++phil

help. i have an 02 sti (import) which had hid lights. i have removed them and fitted blob eye normal lights. i have wired them up and all is fine,but when i came to wiring up the spot lights with a relay they are on all the time. i have tested the headlight wiring and this is where it goes very odd. the wires are both live when off and one becomes the negative when on. so if i connect the feed to the relay it is on all the time.


why?
whats going on?

Chelspeed

Yep it's wired **** about face. Permanent 12V on one side and a switched earth to turn the lights on and off. When the lights are off but a bulb fitted you see 12V on both sides of the bulb. Take the bulb out and they'll be 12V on one side and nothing on the other side, turn the lights on and the nothing side will go to earth. This is the switched earth side.

You need to wire your relay up the same way. Put 12V on one side of the relay coil and connect the other side to the switched earth side of the bulb.

sti+++phil

sounds right but if i put a multimeter on the battery earth and test the terminals it regesters 12v on both terminals?
and where can i change the wiring round to make it normal ?

Chelspeed

Sorry I think you misunderstood what I was trying to say. It's wired up **** about face by subaru from new. All subarus of this vintage are wired this way. You don't need to change anything you just need to wire your relay up to suit.

There's a permanent 12V on one side of the headlamp all the time. If the headlights are turned on then there's an earth on the other headlamp terminal and the headlight is on (12V one side, earth the other, 12V voltage difference across the bulb so it lights up). But if the lights are off they'll be 12V on one side (the permanent live side) but no earth on the other side so, with no current flowing the bulb will be off, but they'll also be 12V on the other side too (12V one side, 12V the other, no voltage difference across the bulb so it's off). Not sure how to explain that better, makes perfect sense to me but I can't explain why very well, just trust me that there is.

I know it sounds crackers doing it that way, I know it's hard to comprehend, I've no idea why subaru chose to do it that way but that's how it is.

As I said before, you need to wire your relay up the same way. Put 12V on one side of the relay coil and connect the other side to the switched earth side of the bulb. Or just connect the relay coil across the two bulb contacts. It may not make sense but trust me it'll work.

sti+++phil

thanks for that, i have wired up the relay so that there is a live feed from the batt and the other side of the coil is to the swiched wire on the light connector. this works fine when the headlights are turned on or even the side lights are on but as soon as all lights are off and ignition too,the spot lights come on??? they work fine with dim/dip??

i will try wiring up tomorrow across the 2 wires on the headlight rather than using the batt.
thanks.