E-fan wiring ideas

[Aloicious]

I get asked about this alot, so I though I'd post them up here. these are some ideas for wiring e-fans. these diagrams are somewhat specific to my setup which is a 2 speed 18" mark VIII fan wired to be controlled through the PCM, with a LED indicator, and high speed override switch. there are many MANY ways to do it, these are just some drawings I made up when I was working on mine.

simple 2 relay setup:

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3 relay setup:

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these are for e-fans that are PCM controlled, and the PCM pinouts are for a 12200411 (aka '411') PCM, and this system is ground controlled (i.e. the PCM will complete a ground to the high or low speed wire to activate the fan in that specific speed) so if you're running a different PCM, or using some kind of aftermarket controller, you'll need to check that out if you want to use these wiring diagrams

next - I did not draw in the fuses, you should ALWAYS fuse any power supply wire, and it needs to be fused according to your setup. IIRC mine is fused at either 10A or 20A on the switched power supply, and I think 50A or 60A on the constant line (this is specific for my Mark VIII fan setup, which can pull alot on startup, so you may not want to fuse things that high on yours.)

the manual over-ride switch, LED indicators, and Diodes are all optional. so if you want to simplify things, those are not required for this diagram to work.

hope that helps someone. feel free to ask questions.

 

[k_pro1992]

Do you have to tune the PCM to control the fans or is the PCM already set up to control the fans?

 

[Aloicious]

depends on what PCM you're using, but most of the time you need to have it tuned. with a transplanted 411 like mine you'll need it tuned.

 

[k_pro1992]

okay, thanks. and for anyone wanting to swap a mark viii fan without it being pcm controlled i found a wiring harness at www.hollisterroad.com.

 

[Aloicious]

yeah you could do that, I don't like external controllers, they never seem to have great reliability, not to mention having additional sensors that need to be added, and the FAR less control you have over the fans with external controllers...

with the PCM, you have FULL control, not just on at 180 or 195 of whatever the sensor you use is....for example, in my 411, I can command the fan on and off at any temperature I want (which is based off the same ECT that the PCM sees for everything else), I can command the fans off at highway speeds where it's not needed, I can command them on or off based on A/C PRESSURES, so its not just on or off with the A/C, its actually on when needed, and off when its not. I can command delays in the fans turning on or off, I can command a minimum run time whenever they are turned on...and more....not to mention the PCM can control all these settings for 2 separate fans (or in the case of the markVIII 2 separate fan speeds)....and the PCM is far more reliable than any aftermarket setup I've ever seen....

I'm not trying to say external controllers are bad and shouldn't be used, everyone has their preferences, and not everyone has the ability or desire to tune the PCM for this kind of stuff...but for those that do, IMO the PCM control is superior.

 

[Steve83]

PCM control is definitely superior. But if it's not a feasible option, these diagrams will work:

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Explanations are in the captions.

 

[GordonCustoms]

What relay amperage would be good to use for the 0411 control, I was looking at getting 2 bosh 75 amp relays but is that overkill and or hurt the system especially for the low speed

 

[Wagonbacker9]

30 amp relays should be plenty. I bought a relay setup basically exactly like this for my Tahoe to remove the mechanical fan.