LML Fan clutch thoughs - Chevy and GMC Duramax Diesel Forum
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post #1 of 30 (permalink) Old 02-15-2016, 09:45 AM Thread Starter
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LML Fan clutch thoughs

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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2006 LBZ, EFI Live from duramaxtuner.com/motor ops with transmission tuning(STRONGLY RECOMMEND), FASS 150 Titanium series, 3 inch MBRP downpipe, 4 inch MBRP free flowing exhaust system(factory muffler back on to kill the drone when towing), Egr blocked and turned off, trans-go shift kit Jr, Edge Cs 85100 for reading data, PPE FPRV race plug, more Mod's to come when cash is in my bank account!
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post #2 of 30 (permalink) Old 04-05-2016, 09:46 AM
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post #3 of 30 (permalink) Old 04-17-2016, 07:42 AM
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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.

Mark Bailey
Hudsonville, MI
2011 GMC Sierra SLT 2500 HD
leveled on 305/55
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post #4 of 30 (permalink) Old 04-18-2016, 03:00 PM Thread Starter
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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

2006 LBZ, EFI Live from duramaxtuner.com/motor ops with transmission tuning(STRONGLY RECOMMEND), FASS 150 Titanium series, 3 inch MBRP downpipe, 4 inch MBRP free flowing exhaust system(factory muffler back on to kill the drone when towing), Egr blocked and turned off, trans-go shift kit Jr, Edge Cs 85100 for reading data, PPE FPRV race plug, more Mod's to come when cash is in my bank account!
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post #5 of 30 (permalink) Old 05-13-2016, 11:12 AM
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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.

09 chevy 3500HD CC 4x4 DRW
Mostly stock with 4.10's

88 Rx7 LT1/700R4 11.04 @ 124mph
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post #6 of 30 (permalink) Old 05-13-2016, 01:57 PM Thread Starter
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Quote:
Originally Posted by LT-x7 View Post
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

2006 LBZ, EFI Live from duramaxtuner.com/motor ops with transmission tuning(STRONGLY RECOMMEND), FASS 150 Titanium series, 3 inch MBRP downpipe, 4 inch MBRP free flowing exhaust system(factory muffler back on to kill the drone when towing), Egr blocked and turned off, trans-go shift kit Jr, Edge Cs 85100 for reading data, PPE FPRV race plug, more Mod's to come when cash is in my bank account!
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post #7 of 30 (permalink) Old 05-14-2016, 02:52 PM
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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.

09 chevy 3500HD CC 4x4 DRW
Mostly stock with 4.10's

88 Rx7 LT1/700R4 11.04 @ 124mph
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post #8 of 30 (permalink) Old 05-15-2016, 05:49 AM Thread Starter
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Quote:
Originally Posted by LT-x7 View Post
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 ing 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 ? 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

2006 LBZ, EFI Live from duramaxtuner.com/motor ops with transmission tuning(STRONGLY RECOMMEND), FASS 150 Titanium series, 3 inch MBRP downpipe, 4 inch MBRP free flowing exhaust system(factory muffler back on to kill the drone when towing), Egr blocked and turned off, trans-go shift kit Jr, Edge Cs 85100 for reading data, PPE FPRV race plug, more Mod's to come when cash is in my bank account!
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post #9 of 30 (permalink) Old 05-16-2016, 09:26 AM
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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.

09 chevy 3500HD CC 4x4 DRW
Mostly stock with 4.10's

88 Rx7 LT1/700R4 11.04 @ 124mph
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post #10 of 30 (permalink) Old 05-18-2016, 02:59 AM Thread Starter
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Quote:
Originally Posted by LT-x7 View Post
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.

2006 LBZ, EFI Live from duramaxtuner.com/motor ops with transmission tuning(STRONGLY RECOMMEND), FASS 150 Titanium series, 3 inch MBRP downpipe, 4 inch MBRP free flowing exhaust system(factory muffler back on to kill the drone when towing), Egr blocked and turned off, trans-go shift kit Jr, Edge Cs 85100 for reading data, PPE FPRV race plug, more Mod's to come when cash is in my bank account!
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