Rally lights for Imprezas
 

Anybody want to hook up aux lighting to their subaru? Specifically Rally lights that are slaved to the high-beams? Subarus run a strange switched-hot AND switched-ground arrangement on their lights which make them confusing as hell when you start playing with them. I fucked around with my meter one afternoon and voila!



http://i249.photobucket.com/albums/g...1relay-1-1.gif

In your picture, because you are using a relay, switch ground or switch power doesn't really make a difference as you are just using the both positive and negative ends to power the coils inside the relay. Switch ground takes into play when you are trying to hook the wires to the existing connector. And usually pin 30 is used as the 12V source (so you can use it to power something in pin 87a when you don't are not using the high beam/rally lights (fog lights??). But great picture nonetheless!

Yeah, the switched ground/switched hot thing makes it strange to add aftermarket wiring to if you're not aware. The forums are full of people hooking up rally or fog lights, according to the directions in the package, that they can't turn off, for instance..

Using the relay on both legs of the high-beams bypasses all the strangeness. Which is why I designed my circuit that way..

easy as pie but I'd run more then one relay when running four large rally lights. call for a quote.

You only need to run one relay as long as your relay, fuses, and wiring are rated for the amps you're pulling.

Amps = Total Wattage / 12Volts

In my case, I'm running 2x 55 watt floods and 2x 100 watt spots. So I got 310 Watts total. Divide by 12 volts and I have 25.8 amps.

I chose 6 guage wiring, a 40amp relay, and fused it for 30amps.

You should never run a relay or any electrical devise at or near capacity and its always a safe rule to consider current draw will double for start up and fluctuates based on may variables. You should run two relays.