Relay looks like this:
http://www.madelectrical.com/images/relayk5.jpg

Buy a kit like this from Summit. Then you get a switch, a relay, some wire, a breaker & a relay. Get another relay locally, and you will be well on your way.
http://store.summitracing.com/largei...=prf-30102.jpg

You may be able to cobble it together cheaper, but not much.

Wiring Diagram
http://img523.imageshack.us/img523/3...ram2sy0.th.jpg


*purple wire needs to be fused at source
*I might use breakers instead of links for the main power - not fuses though.

billy, yeah, there are many ways to possibly wire it. and like in the diagram bonzo showed the grounds go to a temp switch which i didnt even include in my schematics.

I like grounding the temp switch. That is what GM does.

If I was using fan switches, I'd do this, replacing the ECM leads for fan switches (one in head, the other in the water neck or something).
http://img.photobucket.com/albums/v3...995_BOTTOM.jpg

I'm loving my DCC controller, though.

yeah thats a good idea. i just completely forgot about them lol

Makes rigging a manual switch easier too - no extra fuse.

okay -- that works, thanks for that diag.

So all I need to get now is some 10g wire and a relay. Again, as I said before, not sure what kind of relay to get. Went to the radio shack website, and came up with this:
http://www.radioshack.com/search/ind...gkw=relay&sr=1

Which one do I choose?

i suggest this one... for high curent...
http://www.radioshack.com/product/in...entPage=search

After talking to several mechanics (one of which is an 20+ year mechanic) my original though of just using a switch and no relay is correct.

A relay is a switch ... unless there is a sensor (or something else) that dictated when the fan turns on or not there is no need for one. Why would one hook up a switch just to turn another on another switch?

You don't need 8g wire... not even close (maybe if i'm going to wire something in a house with a 120v). I am running 12 g wire to a 30A switch and have not had a single problem. The switch DOES NOT get hot, neither do the wires.

i still recommend a switch.. but its your car.
and i also doubt those mechanics went to Stevens Tech for electrical engineering..

I will say, in the car hobby, everyone has different opinions and thats fine, most of it is trial and error or past experiences. ive seen issues a lot with high amp switched circuits so that formed my veiws. If someone never saw an issue, they woudlnt have a reason to question it. Just always keep and eye on the switch you are using and the connections, if you see any browning of the terminal connectors, change it asap.

Yup, local wrench is smarter then the OEs. And we just fell off turnip trucks.

Good luck.

never said that... but assume away

What I am saying is that I would take my best friend's evaluation (A tech at Ford) and my pops evaluation (20+ year professional mechanic at Ford). He also took many courses in electrical engineering.

Smoking SS:

Been keeping an eye on the switch and the wires and never once have they got hot. Had the fan on for an hour and a half straight the other day and no issue.

bokey- Their skills as automotive specialists are not in question here.

But to value their ideas over that of teams of electrical engineers that design these circuits may be a bit of a mistake.

It's not just the fact that the relay is switched, it's also that the relay prevents against voltage drop. Don't believe me? :mrgreen: Take a look at "headlight upgrade kits" for old muscle. They are all wiring upgrades that include a relay.


http://www.madelectrical.com/electri...adlights.shtml

Now this is a worst case scenario but it kind of shows what I mean...