NEED HELP Fan Clutch from hell lol

Aec678

Member
Ok to kind of make a long story short(er), my water pump went bad which in turn broke my sepentine belt...I ordered the US MOTOR WORKS (MCK1008) water pump and fan clutch kit. (Figuring it be better to change the fan clutch at the same time 🤷🏼‍♀️)...From rock auto..got the new parts, changed them out and now I have P0526 code which before all this, their was no engine light on.. so I read many threads to try to figure this out, many seemed to say it was the harness outside of the radiator that connects to the fan clutch...changed that out with a new harness as the old looked in pretty bad shape....And I still have the code. If I clear the code with my scanner, I can drive fine no light or anything until I shut the car off and every time I restart it the second time, the light comes back with the same code...it’s not overheating and it’s driving nice and smooth...I’m at a lose of what to try next. How would I know if the new fan clutch was bad right out of the box? Should I send it back for replacement? Any suggestions or help is greatly appreciated!!!
 

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TJBaker57

Well-Known Member
I guess it most likely comes down to this... Either the new fan clutch speed sensor is bad, or the wiring to it is bad. I had an issue where my fan worked sometimes and not other times. I traced it to loose connector(s) at the fan clutch end. After testing everything out with a multimeter and proving the connector pin(s) was loose I resolved it cheaply (my favorite way) by using a needle nosed pliers and giving just the slightest twist to the male pins inside the conmector at the fan clutch end. That put enough pressure on the loose conectors to keep them connected. I would only do this after definitively proving a loose connection with a meter.

P1090236.JPG
 

TJBaker57

Well-Known Member
Do you have a decent multimeter? On my 2002 fan clutch I can read megohms from the connector at the shroud down through the hall sensor circuitry and at least know my wires are connected at the clutch end, proving at least that much of the circuitry. BTW it only reads resistance in one direction on mine, must be a diode involved. Reads open circuit the other way.
 
OP
Aec678

Aec678

Member
Can you explain more on how you tested it out? I replaced the connector harness that connects to the harness connected to the fan clutch with a new one cause it looked as if it was the problem...didn’t fix anything though lol. Also how likely would it be to get that code after installing a new water pump and fan clutch? I wasn’t having any issues with the old fan clutch, just the water pump bearings went... 😭
 
OP
Aec678

Aec678

Member
Do you have a decent multimeter? On my 2002 fan clutch I can read megohms from the connector at the shroud down through the hall sensor circuitry and at least know my wires are connected at the clutch end, proving at least that much of the circuitry. BTW it only reads resistance in one direction on mine, must be a diode involved. Reads open circuit the other way.
I know I have a older one, where is the “hall sensor circuitry” id love to test this out...just want to make sure I’m connecting at correct locations and getting the correct results
 

TJBaker57

Well-Known Member
replaced the connector harness that connects to the harness connected to the fan clutch

Having a little difficulty following this. Did the new fan clutch not have a new harness from the clutch to the radiator shroud?
 
OP
Aec678

Aec678

Member
Having a little difficulty following this. Did the new fan clutch not have a new harness from the clutch to the radiator shroud?
Yes it did, I replaced the one on top right that plugs into the outer shroud. Sorry
 

TJBaker57

Well-Known Member
Reading resistance of the fan clutch hall sensor is a pain. Made a little easier with small alligator jumpers here, but still not easy due to not being able to see in there while hooking things up. Anyway, I do this only to prove the wires are connected at the clutch end. I have no idea if the value read has any significance other than to prove a connection exists. It only reads in one direction on mine which is to say if I reverse the colored test leads red vs black it reads an open circuit. My meter reads about 28 or 29 megohms here.

If I were suspicious of an intermittent connection I would wiggle the harness down at the clutch end while observing this reading to see if there were wild fluctuations. Easier said than done.

IMG_20200830_161609.jpgIMG_20200830_161624.jpg
 
OP
Aec678

Aec678

Member
Yes it did, I replaced the one on top right that plugs into the outer shroud. Sorry
I would confirm 5 vdc is there at that shroud connector. Your 2004 is the same as my 2002 in this wiring. This is key on engine off.

View attachment 96604
ok, I’ll definitely test that out after work tomorrow! So if I’m getting the 5vdc, the wiring is good and the fan clutch is bad? Thank you so much for all your info and time!! Seriously it helps a lot!!
 

TJBaker57

Well-Known Member
Moving the black lead to the return signal pin in the connector (2nd from top) yields another value. Again, the value may be insignificant beyond proving a connection exists.

IMG_20200830_161748.jpgIMG_20200830_161800.jpg
 

TJBaker57

Well-Known Member
All this resistance testing is simply to prove there is a complete circuit from the shroud connector to the hall sensor in the fan clutch. There is that connector down in front, right in the fan clutch itself where a bad connection could exist. But with a new unit I would expect it to be good.
 
OP
Aec678

Aec678

Member
All this resistance testing is simply to prove there is a complete circuit from the shroud connector to the hall sensor in the fan clutch. There is that connector down in front, right in the fan clutch itself where a bad connection could exist. But with a new unit I would expect it to be good.
Gotcha, yea I didn’t have any problems until I installed this new fan clutch..so frustrating lol. At least I can test out the connections to prove that out at least
 

aaserv

Well-Known Member
I think the light comes on when there is a 100rpm ( and i could be wrong about the exact number) difference between what speed the computer wants the fan clutch to read and what speed it is actually running. And for some reason the light comes on quicker in some vehicles than others. I know mine is off but it never has set a code so go figure.
Anyway my theory is that the cheaper fan clutches respond to the computer telling it to change speeds slower than the original set up . Im using at the moment a $45 ebay no name fan and I know its doing this but it just overheats and still doesnt set a code.
Your clutch could possibly be running to fast so it never overheats but does set a code, actually in most of the articles and you tube videos on this subject that is a more common problem than not running fast enough.....and it makes sense that they would set it up to throw a code quicker because it would be a big reason to get worse gas mileage which is what they seem to be the most concerned with ....who cares if it over heats.....lol
A good scan tool can ck both of these speeds.... here is a video that shows a lot of info and how to test for that problem.
 

Mooseman

Moderator
You could reinstall the old clutch and if the code goes away, the new clutch is junk.
 

TJBaker57

Well-Known Member
I think the light comes on when there is a 100rpm ( and i could be wrong about the exact number) difference between what speed the computer wants the fan clutch to read and what speed it is actually running.

FWIW, mine almost always has a desired fan speed of 496 RPM (they are multiples of 16) and an actual speed of 1100 RPM to 1200 RPM at 65 mph. Never sets a code. Go figure. Somewhere I once read that 1600 RPM was some sort of threshold for setting the 'fan overspeed' code. These speeds can be monitored with a smartphone app and a $12 elm327 clone Bluetooth adapter.
 

budwich

Well-Known Member
X2 on the app and adapter... cheapest and best way to determine what's up. Complementing this with the stated resistance AND voltage checks will determine the state of your clutch and / or wiring.

I don't see any "checks" for speed differences causing a code. The code is set by "loss of signal"... so it is quite "absolute". Depending on the results of the meter checks, a further check can be done with the same meter / equipment, IF the OP is careful and has some "electrical capability". You can jumper the 5v and ground pins to energize the sensor and hand spin the fan while measuring the output voltage... the need is not exacting but to see some change. Of course, this might be easier said than done given the connector and such but it is out there as opposed to the work needed to change out a clutch.
 
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Mooseman

Moderator
I haven't seen any failed clutches with no engagement give a fan speed code. It mostly happens with locked up clutches and the over speed code.
 

budwich

Well-Known Member
the "fail situation" for the code is to put the fan at 100% so the system does not need to read the speed.
 

TJBaker57

Well-Known Member
the "fail situation" for the code is to put the fan at 100% so the system does not need to read the speed.

So you're thinking in the case of failure the PCM commands 100% fan engagement to the driver module that controls the voltage pulses to the fan solenoid valve? Hmmm... Is this documented somewhere? The fan clutch solenoid valve is spring loaded shut, containing the fluid in the reservoir. Power is required to engage the clutch.
 

TJBaker57

Well-Known Member
from the GM SI manual for the fault code conditions.

Interesting indeed. I wonder why the fan clutch itself wasn't designed to be engaged in a no-power state. If you can spring load a valve shut surely you could spring load it to be open. But then we would get even more of the roar at startup issues.
 

JayArr

Well-Known Member
I still don't understand what you mean by this:

Yes it did, I replaced the one on top right that plugs into the outer shroud. Sorry

This would be the connector that is on the car's wiring harness.

Did you cut the wires and solder on a new five pin male connector?

If that's what you did did you accidentally reverse the grey wires? I don't think the hall sensor will work if the grey wires are reversed, one is 5V supply to the hall sensor and the other is "low reference".
 

JayArr

Well-Known Member
I haven't seen any failed clutches with no engagement give a fan speed code. It mostly happens with locked up clutches and the over speed code.

I have, there is a code for a fan that won't spin fast enough. I had the power wires to the clutch break inside the insulation at the harness side of the shroud connector (male plug). The hall sensor still worked but the solenoid wouldn't activate so the fan just sort of idled along. The Tech2 had a screen that listed the fan speed and an "expected" speed and when the two got too far apart I got an engine light.
 

budwich

Well-Known Member
One thing I need to clarify back at bit when I wrote "a code" associating with speed. I meant to say that this particular code has no "speed limit" in its setting. There may be other codes for speed variations but the OP isn't see those.
 
OP
Aec678

Aec678

Member
I still don't understand what you mean by this:



This would be the connector that is on the car's wiring harness.

Did you cut the wires and solder on a new five pin male connector?

If that's what you did did you accidentally reverse the grey wires? I don't think the hall sensor will work if the grey wires are reversed, one is 5V supply to the hall sensor and the other is "low reference".


I did cut that harness out and replaced with a new one that came with butt connectors, it is possible that the two gray wires got swapped by accident, do you know which pin should read the 5v dc? I haven’t had any time to work on it yet to check anything but I’m planning on it after work Friday...
 

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JayArr

Well-Known Member
A = Black = GND
B = White = 12V
C = Grey = Low reference
D = Dark Blue = Speed Signal
E = Grey = 5V reference
 
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TJBaker57

Well-Known Member
You can see the "A" molded into the purple plastic of the new connector.

I would be careful about that. In post #10 you can see it a little clearer and it is actually "7A" molded in the purple plastic and I believe that end is actually pin "F".
 

TJBaker57

Well-Known Member
Good catch TJ, I was looking at the pic in post #28 and didn't see the "7".
The real good clue is that terminal F is not used!! While the replacement connector will likely have all pins wired, the fan clutch itself will not.
 
OP
Aec678

Aec678

Member
A = Black = GND
B = White = 12V
C = Grey = Low reference
D = Dark Blue = Speed Signal
E = Grey = 5V reference
So just to make sure I’m on the same page...this pic shows the correct pin out? Thanks for everyone’s help, knowledge, & support!
 

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TJBaker57

Well-Known Member
So just to make sure I’m on the same page...this pic shows the correct pin out? Thanks for everyone’s help, knowledge, & support!
I believe that is correct,,, matches up with my post #10 above where my red lead is 5VDC and my black lead is GND
 
OP
Aec678

Aec678

Member
Not getting 5V Dc in that position, could that mean the two gray wires got swapped?EB6BB7B3-6C29-4ED3-8DD6-9A1C43467BE4.jpeg
 
OP
Aec678

Aec678

Member
Reading resistance of the fan clutch hall sensor is a pain. Made a little easier with small alligator jumpers here, but still not easy due to not being able to see in there while hooking things up. Anyway, I do this only to prove the wires are connected at the clutch end. I have no idea if the value read has any significance other than to prove a connection exists. It only reads in one direction on mine which is to say if I reverse the colored test leads red vs black it reads an open circuit. My meter reads about 28 or 29 megohms here.

If I were suspicious of an intermittent connection I would wiggle the harness down at the clutch end while observing this reading to see if there were wild fluctuations. Easier said than done.

View attachment 96605View attachment 96606
Not sure if I’m doing this right lol, this is what I got..
Reading resistance of the fan clutch hall sensor is a pain. Made a little easier with small alligator jumpers here, but still not easy due to not being able to see in there while hooking things up. Anyway, I do this only to prove the wires are connected at the clutch end. I have no idea if the value read has any significance other than to prove a connection exists. It only reads in one direction on mine which is to say if I reverse the colored test leads red vs black it reads an open circuit. My meter reads about 28 or 29 megohms here.

If I were suspicious of an intermittent connection I would wiggle the harness down at the clutch end while observing this reading to see if there were wild fluctuations. Easier said than done.

View attachment 96605View attachment 96606
don’t seem to be getting anything...not sure if I’m checking this correctly 3CF8DF8C-3CA9-4578-8613-5728AB88B555.jpeg
 

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