LIGHT RELAY INSTALL

[mada1234]

Gudday there, i have installed a driving light relay in my mates subaru, buti seem to have hit a technical snag.
I cant obtain a positive trigger from the high beam, to trip the relay i have installed.
If i attatch the trigger (# 86) to the battery it operates the relay, and the driving lights come on,, that side of things is fine.
SO..... here is my question,, do i need to use a "changeover relay" to trip my driving light relay? Or should i have installed another type of relay completly to begin with???
Hopefully someone can steer me in the right direction,, thanks all!

[-Scott-]

I think I'm missing something - like, what's the problem you're trying to solve? If your relay operates the driving lights, why would you need a different relay?

At a guess, the driving lights come on with the headlights, and don't switch with hi/lo? If so, I would guess the Subaru's headlights are negative switching, not positive switching.

Simplest solution is to connect the relay coil (via the driving light switch) across the two outside pins on the H4 socket. These two pins should only have 12V across them when high beam is on, regardless of positive or negative switching.

[mada1234]

Thats what i was thinking "Negative switching".
I'll test the original lead that goes to the high beam globe to see if i can get a 12v+ to trip my relay... Would the globe have to be in circut in order to for this to work?? ( ie get a 12v+ reading on the hi beam lead)
Or can i just unplug the lead from the hi beam globe and insert multimeter probes to find a 12v+reading?..
Thanks again!

[chimpboy]

Simplest solution is to connect the relay coil (via the driving light switch) across the two outside pins on the H4 socket. These two pins should only have 12V across them when high beam is on, regardless of positive or negative switching.

I agree. And if you want to run a switch as well you can just interrupt either of those two wires; it doesn't matter which one.

The point is you don't need to find +12V, you just need to use two wires from the headlight plug.

[mada1234]

Mmmm, the subaru doesnt have a standard h4 globe, it looks like a different type alltogether.
It has just two wires(like normal) that plug onto the hi beam light.
It seems wierd to me,,, but wouldnt i cause a short or some sort of problem by joining my trigger wire from relay(#86) to BOTH of these wires???
Im only asking as i have never dealt with a negative switched system before doing this.
Thanks for your patience! Mada1234

[-Scott-]

but wouldnt i cause a short or some sort of problem by joining my trigger wire from relay(#86) to BOTH of these wires???

Yes. That would cause a short.

Connect #86 to one of the wires, and #85 (currently connected to ground/chassis?) to the other wire. Put your driving light on/off switch in either wire - shouldn't matter.

[mada1234]

Mmm, that seems to sound less dangerous, thanks!!
Is there a way for me to test/check which wires from the hi beam i would connect #86 and #85 to??

When i had #85 connected to a body/chassis point, i was unable to trip the relay,,, although, it works when connected to the battery negative terminal(so thats where #85 will stay now!).
I Know the body/chassis is earthed because there is an earth strap off the negative post across to the nearby panel,hence i expected the relay to operate when #85 was connected to the same panel.
Thanks again!
Confused Mada1234

[-Scott-]

Mmm, that seems to sound less dangerous, thanks!!
Is there a way for me to test/check which wires from the hi beam i would connect #86 and #85 to??

For a "normal" relay, it shouldn't matter which wire goes where. If you are really worried, check the two wires when the high beam is on, connect #85 to the 0V wire and #86 to the 12V wire.

[mada1234]

Thanks heaps for all your help so far, ill be checking those wires when i next get time to finish the job..
Ill post back when complete, to let you all know how i went!
Thanks Thanks Thanks!