Fan Clutch Solenoid Aftermarket Replacment

joelnelson1207

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Hey Colt,

Great video. Thank you.

What were your symptoms that led you to replace this fan solenoid?

FYI - here is a fan clutch solenoid error I am dealing with. What this your problem?

 

BERZERKER888

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2 simple tests... before you start up the truck.. see if the fan spins freely with your hand...it should not
second, when your truck is aired up and you hit the kill switch, you should hear it purge...if not , it might be shot or needs to be cleaned..here is a video from Dave and Sean....

 

BERZERKER888

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and if your fan soleniod is not working and needs to be replaced...they are very difficult to find..MME has crap shoot soleniods for ..wait.. wait.. $300.. but since most of us rather not get hosed by MME , there is an alternative from The Mad LMTV Scientist himself Ronmar...it's 1/10 the cost, quieter and works like a champ


 

CallMeColt

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Hey Colt,

Great video. Thank you.

What were your symptoms that led you to replace this fan solenoid?

FYI - here is a fan clutch solenoid error I am dealing with. What this your problem?

It doesn't sound like it is the solenoid, it sounds like you have some sort of short or ground issue somewhere that is causing an overload that's making a breaker trip & causing a full power shut down. It could be 100's of things really. Electrical issues are a pain in the rear, they can take a while to isolate... especially if they don't happen consistently.

At the end of my video, I do the test to show how the solenoid is supposed to work when it is properly letting air go to the fan clutch & not with the power on & off with the air tanks full. If you are hearing the clutch purge when you get to around 200 deg., it's doing what it should. Your problem is for sure on the electrical side.
 

CallMeColt

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and if your fan soleniod is not working and needs to be replaced...they are very difficult to find..MME has crap shoot soleniods for ..wait.. wait.. $300.. but since most of us rather not get hosed by MME , there is an alternative from The Mad LMTV Scientist himself Ronmar...it's 1/10 the cost, quieter and works like a champ


This is exactly what my post & video is about.... this solenoid & I reference this video & Ronmar in the video description. He was the one who shared it with me after I tried 3 other options with failure each time. Very grateful that he found this!
 

joelnelson1207

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Thank you! This is very good info. But I don't know it addresses my issue(s). My fan solenoid IS working, BUT when temp reaches 200F solenoid opens, fan engages, BUT I get an immediate total electrical shut down in cab. All gauges go dead, power to fuel shut off solenoid is cut, engine stops. I can then cycle the master power switch, OFF, then ON, start the truck as normal. And all is functional UNTIL temp reaches 200F and shut down cycle starts again.

Question:
- Is this a wiring issue(s)
- Or, if the fan clutch solenoid is failing how/why would it cause a total electrical short of the truck

Ideas?
 

joelnelson1207

New member
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Location
Reno, NV
It doesn't sound like it is the solenoid, it sounds like you have some sort of short or ground issue somewhere that is causing an overload that's making a breaker trip & causing a full power shut down. It could be 100's of things really. Electrical issues are a pain in the rear, they can take a while to isolate... especially if they don't happen consistently.

At the end of my video, I do the test to show how the solenoid is supposed to work when it is properly letting air go to the fan clutch & not with the power on & off with the air tanks full. If you are hearing the clutch purge when you get to around 200 deg., it's doing what it should. Your problem is for sure on the electrical side.

Thanks Colt,

Yes, I agree, I don't think it is a solenoid issue either. There is some electrical short. Do you have any suggestions on where to even start to trouble shoot this?

Thanks for your time,
- joel
(775) 223 6633
 

CallMeColt

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Thanks Colt,

Yes, I agree, I don't think it is a solenoid issue either. There is some electrical short. Do you have any suggestions on where to even start to trouble shoot this?

Thanks for your time,
- joel
(775) 223 6633

My best advice is to look at the wiring in the Technical Manual for the Fan Clutch Solenoid, see where it grounds out, & check that first. Then, trace that wire & see if insulation has broken making it cause some sort of back feed. It's strange, because, when the solenoid dumps air the engage the clutch, it is actually cutting power. So, the circuit is dead when it's killing power to your truck. It's possible power from the solenoid circuit is powering something it should not be? Pull the breaker for the fan clutch solenoid & see if the truck will power up.

That's all I can really think of to start with without hand on via a forum thread. The wire diagram will be your friend with this issue for sure.
 

CallMeColt

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what is the original, NSN?
I don't remember. Looked it up a bunch of times. It's irrelivant because it's a dead end anywways. You can't get that part anymore with exception of a few that Midwest Military Equipment has as old stock for a high price. Possible that some may pop up on eBay in the future, but, no matter what, they will all be old. The new solenoid will be fresh & not have deteriorating rubber in it. Also, is much cheaper. :)
 

Ronmar

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Thank you! This is very good info. But I don't know it addresses my issue(s). My fan solenoid IS working, BUT when temp reaches 200F solenoid opens, fan engages, BUT I get an immediate total electrical shut down in cab. All gauges go dead, power to fuel shut off solenoid is cut, engine stops. I can then cycle the master power switch, OFF, then ON, start the truck as normal. And all is functional UNTIL temp reaches 200F and shut down cycle starts again.

Question:
- Is this a wiring issue(s)
- Or, if the fan clutch solenoid is failing how/why would it cause a total electrical short of the truck

Ideas?
That most definitely sounds like wiring or a component issue. As Colt mentioned the 200f thermal sw removes power from the circuit to de-energize the coil of the solenoid valve, vent the clutch air and engage the fan.

Not where I can look at a schematic right now, but will look later this evening and see if maybe I can come up with a likely scenario for your issue…
 
Last edited:

Ronmar

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Port angeles wa
Thank you! This is very good info. But I don't know it addresses my issue(s). My fan solenoid IS working, BUT when temp reaches 200F solenoid opens, fan engages, BUT I get an immediate total electrical shut down in cab. All gauges go dead, power to fuel shut off solenoid is cut, engine stops. I can then cycle the master power switch, OFF, then ON, start the truck as normal. And all is functional UNTIL temp reaches 200F and shut down cycle starts again.

Question:
- Is this a wiring issue(s)
- Or, if the fan clutch solenoid is failing how/why would it cause a total electrical short of the truck

Ideas?
OK reviewing the schematics I think you have 2 things going on:
1. The fan control thermal switch is bad and when it is hitting 200F, it is removing power from the solenoid, but at the same time switching it to ground. The fan power is drawn thru CB22, but that gets power from the switched ignition relay, like everything else that uses 24v ignition power.

2. You have a bad connection in the switched ignition circuit, perhaps even the control power relay K2’s contacts… when that fan switch hits 200F and shorts, it adds a load path to ground which due to a bad connection causes the X6 buss(control power relay output) to brown-out. This squashes trans controller, fuel cut solenoid ect and brings things to a screeching halt…

Easy test: Disconnect the thermal switch connector in the upper radiator pipe. Run the engine and use the fording switch in the upper left corner of the inst panel to control the fan. This will probably work OK. Since the only change is the disconnected switch, if it works OK, thats your problem…

Good Luck!
 

BERZERKER888

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OK reviewing the schematics I think you have 2 things going on:
1. The fan control thermal switch is bad and when it is hitting 200F, it is removing power from the solenoid, but at the same time switching it to ground. The fan power is drawn thru CB22, but that gets power from the switched ignition relay, like everything else that uses 24v ignition power.

2. You have a bad connection in the switched ignition circuit, perhaps even the control power relay K2’s contacts… when that fan switch hits 200F and shorts, it adds a load path to ground which due to a bad connection causes the X6 buss(control power relay output) to brown-out. This squashes trans controller, fuel cut solenoid ect and brings things to a screeching halt…

Easy test: Disconnect the thermal switch connector in the upper radiator pipe. Run the engine and use the fording switch in the upper left corner of the inst panel to control the fan. This will probably work OK. Since the only change is the disconnected switch, if it works OK, thats your problem…

Good Luck!
I whole heartedly disagree with Ronmar overly simplistic "diagnosis" .. it's either the Fetzer Valve or Muffler Bearing ..and you'll need a 2 way adjustable tent wrench to fix it....touche' Ronmar... (insert mic drop)
 
Last edited:

TomTime

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I whole heartedly disagree with Ronmar... it's either the Fetzer Valve or Muffler Bearing ..and you'll need a 2 way adjustable tent wrench to fix it....touche' Ronmar... (insert mic drop)
I have the valve but I need one of the muffler bearings. Got a spare one?
 

joelnelson1207

New member
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Location
Reno, NV
OK reviewing the schematics I think you have 2 things going on:
1. The fan control thermal switch is bad and when it is hitting 200F, it is removing power from the solenoid, but at the same time switching it to ground. The fan power is drawn thru CB22, but that gets power from the switched ignition relay, like everything else that uses 24v ignition power.

2. You have a bad connection in the switched ignition circuit, perhaps even the control power relay K2’s contacts… when that fan switch hits 200F and shorts, it adds a load path to ground which due to a bad connection causes the X6 buss(control power relay output) to brown-out. This squashes trans controller, fuel cut solenoid ect and brings things to a screeching halt…

Easy test: Disconnect the thermal switch connector in the upper radiator pipe. Run the engine and use the fording switch in the upper left corner of the inst panel to control the fan. This will probably work OK. Since the only change is the disconnected switch, if it works OK, thats your problem…

Good Luck!
Ronmar!

I just logged in to Steelsoldiers to search for a MTV M1083 Technical Manual with ELECTRICAL SCHEMATIC DIAGRAM and here you are already ahead of me :)

#1 - Where can I download the electrical schematic you are looking at? (Yes, I did many google searches and .pdf searches but I can't find it. I can only find FMTV's manuals and I don't know if their schematics are same as MTV's. I am doing something wrong w/ my search quere because I am not finding what you are looking at).

Can you share link to electrical schematic please?

#2 - I bought an electrical signal tracer and tomorrow's projects is to trace the short down, BUT it would make life much easier if I had a diagram ;)

#3 - I will follow your troubleshooting idea (e.g. disconnect thermal switch connector in upper radiator pipe, etc) and follow up with you with a progress report.

#4- Your info is super generous and helpful and already gives me a path to solve this. I am very grateful and you've saved me a TON of time. Thank you friend.

Sincerely,
Joel

PS - would you be willing to speak over the phone? My # (775) 223 6633
 
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