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Discussion Starter #1
For all us who are towing heavy(not me very often) i've bin thinking about this, i do work for GM and the second i touched an LML i saw that fan clutch i though how can we get that on older trucks. so today i decided to review the diagrams(if it didnt pop up here ill repost it)

next time i get one in the shop and im doing a repair to it im going to jump the circuit on load side of the relay and see if the fan is commanded on full tilt. Well if this is the case and it works could be a very simple wiring set up for you guys who tow heavy, i know its modulated from the ECM but for towing its simple in my eyes, we want as much flow as possible.

but some input from everyone else would be nice, and or if someone out there is making this kit would be good for a few customers of mine who HATE that clutch fan
 

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id like to see what you come up with as well. I have an lml so I have the electric clutch already but be interesting to see what you come up with.
 

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Discussion Starter #4
Well i have bin playing with it some, had a few HG jobs that got in the way and now an LBZ with some serious bottem end issues, and this is stuff i do on the side, works not bin very busy on the LML's, which is a good thing. but if you do ground the relay it does command the fan on full. i gotta get a junkyard one with harness to put on my LBZ to put into the real world
 

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Any headway on this project?!
I'm looking to swap to a LML fan clutch also. I actually purchased a new LML unit a few months ago, but thats as far as I have got with the swap.
 

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Discussion Starter #6
Any headway on this project?!
I'm looking to swap to a LML fan clutch also. I actually purchased a new LML unit a few months ago, but thats as far as I have got with the swap.
i wont lie dude, i havnt had time at all, if you bought the fan clutch did you get the jumper harness and the pigtail from GM? if not go to a junk yard and cut them off, i am 99% sure it will work. its a 5 wire pigtail but 3 wires are for the ECM to see the speed the fan is going, which we just want it on or Off, if you wire black wire to ground(this is at the 5 pin connector for the fan clutch, and the WHITE wire will be the wire you apply 12v to, make sure you install a 10 amp fuse, and use a relay to control it, its probably less then 5 amps to make it run, if you have any issues Email me [email protected] and we will start texting and make it work.
i am hoping i can get this engine build done and the other mounting jobs done. i gotta open my own shop... working at a dealer and doing work on the side is getting to be a little much
Anyways Keep me posted if you get going before me dude
 

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I have a lot going myself and just haven't had time figure out how I want to do it. Now that it's warm again I need to make time and get it done.
The new clutch came with a pig tail about 6" long and my plan was to tap into the wires I need right there.
My original plan was to wire it up exactly as you describe. But in my internet travels it seems like there is some dispute if it actually is that simple to make work. The factory setup uses PWM to modulate fan speed. So the unknown is will it produce a full-lock situation if you feed it a straight 12v when it is expecting a PWM signal? One thread mentions the fan defaults to locked, so it would need 12v to unlock, not sure if that is really the case.
Could you send me your wiring diagram above? For some reason it's way too small to read on my computer.
 

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Discussion Starter #8
I have a lot going myself and just haven't had time figure out how I want to do it. Now that it's warm again I need to make time and get it done.
The new clutch came with a pig tail about 6" long and my plan was to tap into the wires I need right there.
My original plan was to wire it up exactly as you describe. But in my internet travels it seems like there is some dispute if it actually is that simple to make work. The factory setup uses PWM to modulate fan speed. So the unknown is will it produce a full-lock situation if you feed it a straight 12v when it is expecting a PWM signal? One thread mentions the fan defaults to locked, so it would need 12v to unlock, not sure if that is really the case.
Could you send me your wiring diagram above? For some reason it's way too small to read on my computer.
i understand why they seems to think it being PWM and direct 12V being an issue. but its a fucking electro-magnet they only use PWM to keep drag off the engine for that little extra boost in fuel milage. plug when im watching the scan tool during a service regen it is commanded on at 100%. now if they want me to go all nerd on it i can grab my amp clamp and my verdict D7 and current ramp the white wire and or current ramp it at 50% PWM, so your going to see X number of amp and 12V being applied directly on and off. i am not an electrical expert but i know enough to say who gives a fuck? it makes sence it should work so try it!. this is one time i wish i had an LB7 LLY that fan clutch is a joke to replace, being an LBZ slight more of a pain. but NOW i think i am going to just try it on my buddies LML and jump the relay
 

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It makes sense to me it should work also, but I'm not sure I want to be the guinea pig to try it and hopefully not burn up a new clutch. I noticed that some of the electric fan controllers use a Pwm signal to modulate fan speed. That might be a good option since ideally the clutch would lock up on its own at a pre determined temperature and you could have a override switch to manually lock lower.
 

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Discussion Starter #10
It makes sense to me it should work also, but I'm not sure I want to be the guinea pig to try it and hopefully not burn up a new clutch. I noticed that some of the electric fan controllers use a Pwm signal to modulate fan speed. That might be a good option since ideally the clutch would lock up on its own at a pre determined temperature and you could have a override switch to manually lock lower.
Well to burn one up i highly dought i've watched them scream out back at 100% duty cycle on 2011's doing reductant quality test's for 70 min at a time and just time out, go for a 20 mile drive and do the test again. as for burning it up i really can't see that happening. and making a controller seems pointless to me. its eathor you want locked or not.

Anyways ill try and get the ball rolling shortly. i am shocked NO ONES done this yet.
 

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Even the electric controlled viscous fan clutches will do it. When the fan clutch is cold, the fluid in the clutch is very thick, and engages. Once that 10,000 weight(or thicker for some clutches) silicone oil warms up, it returns to normal operation. The old style fan clutch uses a thermal spring to control the engagement, an electro viscous clutch replaces the bi thermal spring with an rpm sensor and an electric solenoid to take the place of the bi thermal spring that origanally engaged the clutch. So even though its an electric control, it still has all the same quirks of it's mechanical predecessor.

 
...
 

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Well to burn one up i highly dought i've watched them scream out back at 100% duty cycle on 2011's doing reductant quality test's for 70 min at a time and just time out, go for a 20 mile drive and do the test again. as for burning it up i really can't see that happening. and making a controller seems pointless to me. its eathor you want locked or not.

Anyways ill try and get the ball rolling shortly. i am shocked NO ONES done this yet.
I am pretty surprised no one has done this also.
I'm not very knowledgeable when it comes to electronics, so correct me if I'm wrong. But 100% duty cycle commanded from a PWM controller is not the same as a straight 12V is it?

C20Elephant I don't think anyone is trying to eliminate the quirks from the viscous part of the clutch. It's the inconsistency and lack of control of the engagement that I'm looking to eliminate.
I think it would be awesome to eliminate both and use something like a Horton clutch, but for me the cost makes it not worth it. But on the flip side, the factory LML clutch didn't cost much more than a stock LMM unit.
 

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I am pretty surprised no one has done this also.
I'm not very knowledgeable when it comes to electronics, so correct me if I'm wrong. But 100% duty cycle commanded from a PWM controller is not the same as a straight 12V is it?

C20Elephant I don't think anyone is trying to eliminate the quirks from the viscous part of the clutch. It's the inconsistency and lack of control of the engagement that I'm looking to eliminate.
I think it would be awesome to eliminate both and use something like a Horton clutch, but for me the cost makes it not worth it. But on the flip side, the factory LML clutch didn't cost much more than a stock LMM unit.
I had thought about it..

It was just an FYI, you need to determine what year truck the clutch will come from on the LML unless the part number remains the same, if not stick with the early 2011 as some electrical had changed 2011.5.

These will keep you busy for awhile...

gmupfitter.com

Light duty prior 2011

GM UPFITTER - Body Builder Manuals
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2003 to 2007.5 electrical

http://gmupfitter.com/files/media/photo/99/2006_LD_CKFullSizeElectrical.pdf
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2007-2008 electrical

http://gmupfitter.com/files/media/photo/87/2007_LD_ElectricalPickupsChassisCabs.pdf
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2009 electrical

http://gmupfitter.com/files/media/photo/477/2009_LD_ElectricalPickupsChassisCabs_100813.pdf
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2010 electrical

http://gmupfitter.com/files/media/photo/479/2010_LD_FS_PU_Elec_1_7_D1_100813.pdf
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2011 electrical

http://gmupfitter.com/files/media/photo/482/2011_LD_ElectricalPickupsChassisCabs_100813.pdf
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2012 electrical

http://gmupfitter.com/files/media/photo/484/2012_LD_ElectricalPickupsChassisCabs_100813.pdf
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2013 electrical

http://gmupfitter.com/files/media/photo/487/2013_LD_ElectricalPickupsChassisCabs_100713.pdf
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2014 electrical
https://www.gmupfitter.com/files/media/photo/474/2014 BBM Electrical section_10_18_2013_WIP.pdf
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Discussion Starter #14
Well i have bin putting though into it, and if we remove the clutch fan then coolant temp will probbally fluctuate a lot more, so if your not watching the temp all the time it might be a bad idea unless your towing all the time and watch that temp. i've talked to guys with an LBZ/LMM with worn out fan clutch and they said they had to play with the temps alot more, so a controller would be a good idea, i for sure can not sort that out.

and for supplying 12 directly to it, im going to use my vedict and back prob the white wire to see what is going on at 100% duty cycle. just boils down to when i get to it
 

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Well i have bin putting though into it, and if we remove the clutch fan then coolant temp will probbally fluctuate a lot more, so if your not watching the temp all the time it might be a bad idea unless your towing all the time and watch that temp. i've talked to guys with an LBZ/LMM with worn out fan clutch and they said they had to play with the temps alot more, so a controller would be a good idea, i for sure can not sort that out.

and for supplying 12 directly to it, im going to use my vedict and back prob the white wire to see what is going on at 100% duty cycle. just boils down to when i get to it
I would be very interested to know what type of signal you see at 100% duty cycle.

I don't think it would be a huge issue having it just on a switch. I'm not sure if I have ever had the fan clutch lock when I'm not towing, and I live in an area with steep hills and 100+ degree summer days.

If the PWM signal is in fact unnecessary my plan was to use something simple like this JEGS Performance Products 10561, JEGS Electric Fan Wiring Harness Kits | JEGS Performance Products and then of coarse wire a toggle switch to close the relay at lower temps when desired.
 

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Pulled on grade in eastern Utah on I 70 W yesterday night with a 30 ft camper. Coolant with up to 221 then fan came in. Grade reduced but still uphill. Fan off at 190. Grade increased in steepness. Coolant was up to 226 before fan kicked back in.
 

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Discussion Starter #17
as chevor pointed out there are fan clutches out there that can control the heat situation very easily, but on a side note i mentioned it to our electrical guy today, and he mentioned using a rheostat to control the voltage, how its an electromagnet a rheostat might work out quite well, so now to get everything to gethor and get off my lazy ass and attempt it purely for curiosity. guy's
 

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Would be interested also if the LBZ fan clutch can be swapped to the electric fan clutch. My factory fan clutch wasn't working properly (so I thought), when first started and it's 95 plus degrees outside and with remote start to cool down with the a/c and it would not work properly since no air movement was happening. Purchased a new clutch and same problem. Plus does anyone know what the cfm is for the LBZ fan anyway? Been thinking about electric fan but have seen both good and bad reviews for it. Any help would be appreciated.
 

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Would be interested also if the LBZ fan clutch can be swapped to the electric fan clutch. My factory fan clutch wasn't working properly (so I thought), when first started and it's 95 plus degrees outside and with remote start to cool down with the a/c and it would not work properly since no air movement was happening. Purchased a new clutch and same problem. Plus does anyone know what the cfm is for the LBZ fan anyway? Been thinking about electric fan but have seen both good and bad reviews for it. Any help would be appreciated.


I would start with cleaning your cooling stack. If the fan slightly spinning at idle can't keep the condenser cool, I'm gonna guess you have very restrictive air flow.


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Discussion Starter #20
Clean your stack as kow said. You will notice a differnce. Or a 2886 fan clutch or whatever Malibu and kow are using

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