Using PCM to control aftermarket electric radiator fan?

Link said:
This was a very interesting thread. I'm not planning any electric fan conversions but still enjoyed reading and learning. Aside from the one poster shitting in the thread, the rest of the posts have been interesting. I did do the Ford fan/heavy duty fan clutch mod and love it.
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The information regarding the jtec pcms from the 97-04 jeeps is pretty sparse, so hopefully this helps some people who cant run a mechanical fan. Id run the stock fan on mine, but the front half doesnt work with the stock radiator, and it hung about 3 inches below the frame rails and the fan hit the upper link bars. A lot of the aftermarket fan controllers are notoriously failure prone, and since the programming/circuitry exists its a viable option.

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SkylinesSuck said:
Awesome. Didn't even know you could change that parameter. Very helpful info man. Hope you stick around and continue to share!
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I found that tune file in the hptuners forum. Took a gamble and flashed it to my pcm. Spent a good part of the day playing with settings til i got it to work the way i wanted. I also added the terminals for the maxi fuses to the factory pdm, so the fan relays are fuse protected and i have 3 additional fused outputs. Just need to clean up the wiring and it'll be good to go
 
I did the same with the PDC. I love how clean and factory it makes everything look.

So you need to start with that OS on the time then, there's no changing it? Any chance I can get that file from you or a link to it? I don't know what the XJ PCM I have has on it and I'm at work so can't check until late tonight around the time Santa comes to town.
 
I dont know if thats the only OS that works, i just know that one does and the other one pulses on start/stop. If its a xj pcm, id imagine it will work since they used an aux fan. Just play with the temp settings and set dc fans to disable(should be set that way on the xj tune). I have a 2000 xj pcm i pulled the file from to look at settings, but its a coil rail OS. It'll cost 1 credit to flash that other file to the pcm, even if youve already licensed your current pcm. If you want, i can post both those files if you want to poke around in em.
 
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SkylinesSuck said:
I will take a look at when I got when I get home and get back to you. Thanks a ton man!
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Oh and another thing ive noticed is since the native units are metric in the programming, sae doesnt always translate right in the editor. Set the units to native in tools/options and use the unit conversion tool to get the celcius numbers from your farenheit numbers. You usually have to close and reopen the file to get it to switch over.
 
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SSTJ said:
Really interesting thread. Stumbled upon it when wondering whether an electric fan would free up any power for my 2.5. I see @Wildman commented on the Taurus option, but I'm interested in where things stand for @Steel City 06 's approach. Any updates here?
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Can’t speak for the 2.5 but the Taurus fan was my solution for heat issues with a super charged 4.0. Running a two speed controller from dccontrol.com. Runs cool in the summer with AC on. Should be plenty for a 2.5.
 
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SSTJ said:
Really interesting thread. Stumbled upon it when wondering whether an electric fan would free up any power for my 2.5. I see @Wildman commented on the Taurus option, but I'm interested in where things stand for @Steel City 06 's approach. Any updates here?
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I haven't tried anything since the last few attempts. My current plan is to control it with an Arduino (which can also support a lot more than just a fan) but I haven't had time to work on it.

I did source a 750 watt brushless SPAL 17" fan that perfectly fits into the OEM fan shroud, so mounting it should be easy. Should easily pull several thousand CFM.
 
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freedom_in_4low said:
Sorry if it's posted already, but do you have an upgraded alternator?
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I have a 180 amp Remy alternator for a Durango. I've considered getting a higher amperage alternator for winching, but really haven't needed it. Typical duty cycle while driving is only about 10-15% of rated capacity, so not really worried about the extra load
 
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Steel City 06 said:
I have a 180 amp Remy alternator for a Durango. I've considered getting a higher amperage alternator for winching, but really haven't needed it. Typical duty cycle while driving is only about 10-15% of rated capacity, so not really worried about the extra load
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Went with 2 stock electric fans on my XJ, from the stock setup of 1 electric and the mechanical. Was great in normal driving and the fans didn't run that much, and had no troubles managing the Arkansas heat. But on trail rides they stayed on high pretty much the whole time. The temps were fine but the noise was kinda annoying. Enough so that I though a more trail-oriented jeep would be better with the mechanical fan just for the noise factor.

All this just to say that the duty cycle can go to 100% for hours on end when you're crawling.
 
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Steel City 06 said:
I haven't tried anything since the last few attempts. My current plan is to control it with an Arduino (which can also support a lot more than just a fan) but I haven't had time to work on it.

I did source a 750 watt brushless SPAL 17" fan that perfectly fits into the OEM fan shroud, so mounting it should be easy. Should easily pull several thousand CFM.
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Got it. I'll stay posted and hope to hear how it goes. Thanks for this write-up.
 
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srimes said:
Went with 2 stock electric fans on my XJ, from the stock setup of 1 electric and the mechanical. Was great in normal driving and the fans didn't run that much, and had no troubles managing the Arkansas heat. But on trail rides they stayed on high pretty much the whole time. The temps were fine but the noise was kinda annoying. Enough so that I though a more trail-oriented jeep would be better with the mechanical fan just for the noise factor.

All this just to say that the duty cycle can go to 100% for hours on end when you're crawling.
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Should have specified that it is my alternator that runs at about 10-15% duty cycle during normal driving. I figure the fan would be a lot higher at low vehicle speeds. Right now I run the explorer 11-blade fan which works very well, but is a major power suck at higher RPMs when the clutch is engaged.
 
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Steel City 06 said:
Should have specified that it is my alternator that runs at about 10-15% duty cycle during normal driving. I figure the fan would be a lot higher at low vehicle speeds. Right now I run the explorer 11-blade fan which works very well, but is a major power suck at higher RPMs when the clutch is engaged.
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Will also says the Taurus fan is like 50amp draw on high speed. I’ve had no voltage issues unless I run the winch hard. It will set the “check gauges” light due to voltage drop but resets once you cycle the key.
 
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Dan_Goodwin said:
You have me interested. I'm definitely following to see where this goes.

I have done a very similar swap in my 2003 Silverado which appears to work the same way. GM didn't swap to electric fans until 2005, but the high and low speed control pins were present in my 2003's ECU - they just had to be turned on via tuning. I bought an aftermarket harness with relays that pinned into my factory ECU plug for the fan controls.
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In 1983 I was in Sales (for a short time!) and had to travel, a lot. I bought a new Buick Century. It had electric fans. One month after I bought the car, the temperature sensor on the engine block failed. The fans did not engage. I had no way of knowing this fact. Five weeks after I bought the car, the engine overheated and locked up. The car was towed back to the dealership and a new engine was installed, with a new temperature sensor. I traded it in for something different.
This illustrates the ancient maxim of computers and any kind of control circuitry: GIGO Garbage In, Garbage Out.
The failure of a $3 sensor caused the failure of a $4000 engine, plus labor.
The moral of the story: KISS.
 
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SSTJ said:
Really interesting thread. Stumbled upon it when wondering whether an electric fan would free up any power for my 2.5. I see @Wildman commented on the Taurus option, but I'm interested in where things stand for @Steel City 06 's approach. Any updates here?
Click to expand...

For the 2.5 you could use the single speed fan from a 3.0 Taurus and have less wiring to deal with. Mine is finally dying after over a decade of use up here so I am going to use a Spal 16" 30102049 https://www.amazon.com/Spal-30102049-Curved-Blade-Performance/dp/B003PB9QRO?tag=wranglerorg-20 and see how that works.
 
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