Ok, my third brake light has a VTEC sticker. The sticker lights up whenever I'm on the brakes. I want to activate the same light using the VTEC signal as a trigger from the ECU. I know how to wire the relay from the VTEC signal to the third brake light but I'm concerned the current will return via the brake light circuit and vice-versa.

Do I need to use diodes on each circuit to prevent this from happening? If so how do I wire them in?

Thanks!

 

Instead of using diodes, which would work, you could just use another relay on the brake light side of the lamp, and that would seperate the VTEC circuit from the brake lights. Only downside is it will click when you hit the brakes.. but if I'm not mistaken there is space in the 3rd brake light housing (Inteagra?) for a relay. The VTEC signal relay of course you could put anywhere since you need to run a wire back there anyways.

 

Good idea!

But just for my own knowledge, if I were to used diodes, how would I wire them in (polarity)?

 

You would use 2 diodes in one in series on the VTEC signal feed and one in series on the light feed and 'point' them both to the lamp. "Stripe" toward the lamp I think, but I might be thinking backwards. Whichever it is do them both the same way, you don't want your VTEC kicking in when you're pulling upto the stoplight