Electric cooling fan wiring question

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Downtime!

Downtime!

Better With A Big Block
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Did a search, but didn't find exactly what I'm looking for, so I'll ask the experts.

I'm in the process of adding a new 26" core radiator and dual 12" electric fans to the Scamp. Everything is now mounted and I'm ready to start roughing in the wiring. I'm using one of Jegs dual electric fan relay kits for the wiring, and the instructions that came with it are pretty lame. That led me to an internet search for wiring diagrams, which led me to the Champion radiator site, where I found a pretty nice diagram that explained nearly everything well enough that even a rank amateur such as myself could understand it. Everything, that is, except one thing. In the diagram, it show the yellow wire going to the ignition switch, or a stand alone switch, and I want to use the ignition switch method so I don't have to worry about forgetting to turn off the fan switch.

Which leads me to my question - what wire am I looking for to hook in to, and is there a wire that will work under the hood, for ease of wiring and to keep the runs as short as possible?

Many thanks in advance for the guidance.
 
Is there already relays in the wiring system for the fans?

I can help you, but I need to know this first so I know where to go from where you are.

The yellow wire you speak of is power to the fans, but they MUST have at least one relay in the system.
 
Here's the diagram from Champion. The wires are all the same color in the Jegs kit. I have everything sorted out except the yellow wire. Is there a convenient place to tap into under the hood, or do I need to go inside the cabin for that?

relay.jpg
 
Ok, so there is already a relay and you have two choices.
Connect the yellow to a switched power supply, or a non switched power supply.

Switched the fan will only be able to come on while the ignition is on, and non switched the fan will come on ang go off determined by the sensor.
(Even if the car is off)

You can connect the yellow wire to an accesory wire at the fuse box that only has power when the key is on for switched.
Or you can connect it directly to the battery positive at the battery or the relay and it will come on and go off as needed without the car running.

I prefer direct to the battery positive because it keeps the pressure down in the cooling system when the car is shut off causing the engine temps to climb.

If you use a test light or volt meter you can determin what accesory fuses are powered with the key on, then pull the fuse box down and splice into the wire, or use an accesory connector for fuse blocks.
You should also pull the fuse out and see which end of the fuse socket does not have power to it and connect at that side. (so the relay is on the fuse protected side)
Personally, I splice into the wire and solder, then heatshrink the joint.
(of course you have to put the heatshrink on the relay wire before you solder them.

The heatshrink can go onto your yellow wire and then bend the original wire at a 180 like this picture. (I showed it in red but but the heatshrink is on your yellow wire.
Once the soldering or whatever is done then slide the heatshrink down over the joint and heat it to shrink.

I hope this answered what you wanted to know.
 

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So, I can just hook the yellow wire (trigger wire?) up directly to the battery and it will do what it needs to do? And if I turn the car off hot, the fans might run for a while until it drops below the preset temp? That might not be a bad way to go. Think I'll give that a shot, and if I don't like it, I'll find a key-on hot wire to tap into.

Thanks!
 
Downtime! said:
So, I can just hook the yellow wire (trigger wire?) up directly to the battery and it will do what it needs to do? And if I turn the car off hot, the fans might run for a while until it drops below the preset temp? That might not be a bad way to go. Think I'll give that a shot, and if I don't like it, I'll find a key-on hot wire to tap into.

Thanks!
Click to expand...

You got it.

At first I was a little concerned about killing my battery if it was on with the car shut off, but I havn't any one issue with it in two years.
I liked the idea of keeping the pressure down on the hoses and the bypass in the cap and I must say I don't think it has ever so much as burped coolant ever, and I live in AZ. :)
 
Should be good for that Texas heat too then! If I can ever get these damn trans cooler lines back on, I'll finish the wiring and giver her a go.
 
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