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Discussion Starter · #1 ·
So I'm full bore into this custom electric fan set up and close to getting it. I have a fully built 6.0, i have 4-12" 2500 CFM cooling fans, with a two stage stand alone temperature controller w/ each set having its own relay set-up, i have upgraded the electrical system to a 320amp system to carry the load of the fans. Now this is where it gets tricky and need some answers. I know disconnecting the fan clutch all together will throw off the PCM. So I want to utilize the fan clutch plug if possible. Is the 5v reference just a positive feed back for the PCM to know that particular sensor is good or does it command and relay information. Also I haven't checked yet because I haven't put the battery's back in but does the 5v reference come from the PCM for from the fan clutch/(sensors) cause it would kind of be determined by the first question. Another thing is if i connect the fan control speed wire to the relay to activate 1 set of fans in theory if i use a resistor on the same line for the 2nd set of fans slightly out of range of were the control wire sends the 1st signal and if the truck does not cool off and it this the second range the will supply the voltage needed to activate the 2nd stage of cooling fans.
 

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Sounds like you are trying to improve the wheel, ...by making it square
but good effort, maybe it will actually be an improvement
keep this thread updated with your findings

The PCM outputs a pwm voltage (12 volts) to control the magnet that operates the valve in the viscous clutch
The RPM feedback is done with an opto sensor (also 12 volts) to provide a pulsed signal back to the PCM
The temp sensors on the engine and transmission help determine the actions of the PCM
along with engine load, AC, and I am sure some other voodoo that Ford thought necessary in the programming

Not sure if on this forum or another, but there was a temperature vs fan RPM chart worked out -- interesting read if you find it
Really thinking those electric fans will not move as much air over the stack as the engine driven fan

I think ask the question of why the original vistronic fan was not performing as it should -- and fix that
Restricted air stack or bad sensor input, would be most of the causes

The "blue wire mod" works to max the fan for those times the driver thinks more cooling is needed
I think modding the original system with a micro controller would also be an option
 

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Discussion Starter · #7 ·
Do you have a part # for specific model?

I would have to look at the 6.0 PCM logic unless @Hydro can clarify.

The dual relay controller may struggle with 4 fans but once I get specifics I can help further.
so im going to use the controller to activate 2 separate set of relays for the fan so I don't overload anything

 

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Discussion Starter · #9 ·
Sounds like you are trying to improve the wheel, ...by making it square
but good effort, maybe it will actually be an improvement
keep this thread updated with your findings

The PCM outputs a pwm voltage (12 volts) to control the magnet that operates the valve in the viscous clutch
The RPM feedback is done with an opto sensor (also 12 volts) to provide a pulsed signal back to the PCM
The temp sensors on the engine and transmission help determine the actions of the PCM
along with engine load, AC, and I am sure some other voodoo that Ford thought necessary in the programming

Not sure if on this forum or another, but there was a temperature vs fan RPM chart worked out -- interesting read if you find it
Really thinking those electric fans will not move as much air over the stack as the engine driven fan

I think ask the question of why the original vistronic fan was not performing as it should -- and fix that
Restricted air stack or bad sensor input, would be most of the causes

The "blue wire mod" works to max the fan for those times the driver thinks more cooling is needed
I think modding the original system with a micro controller would also be an option
would there be a way to utilize a programed Arduino to trick the system? this is my 5th custom cooling fan system but my first on a ford with all the Integrated pcm control issues
 

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I will say tentatively - yes on the Arduino, but really no need unless you are staying with the factory setup
As far as I know the system does not care what the fan does as long as the temperature is controlled -- the feed back circuit only lets the PCM know the fan RPM, then is adjusted to get the heat under control
According to that post I mentioned earlier, the fan speed is ramped up in steps -- if the heat is not controlled in a certain time -- then the next faster step is chosen
I see the failures as an air stack flow problem or sensor giving bad information back to the PCM -- usually people get frustrated and opt for an easy solution

As long as the engine is cooled there would be no de-rating of power -- so your electric system should work -- even with the factory inputs disconnected
A lot of people do the 7.3 mod -- there is a code but no light on the dash
 
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