OK well I am hooking up computer fans for my amp enclosure thats going in my trunk. I will be wiring them to come on with the HU just like the amp so that if the amp is ever on so are the fans. I read that if you run more than half an amp from there you could toast you HU and it even specifically said no fans, use a relay. So I have several extra automotive relays that I have grabbed to have as spares if one goes bad in my car. I have a general understanding of how a relay works, but I'm not exactly sure how to wire it up. I know that my 12V from the radio has to go to one of the prongs in the relay, one of them has to be where it is actually going to get the power from, one has to be the power going from the relay to the source. I'm also assuming that one is for the ground for the 12V from the radio. There are 5 pins so what am I missing?