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Go Back   E46Fanatics > Tuning & Tech > Driveline, Engine & DME Tuning

Driveline, Engine & DME Tuning
Talk about driveline improvements, NA tuning and DME tuning your E46 BMW here. This includes diffs, intakes, exhausts, chips, software and OBD tuning.

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Old 06-18-2012, 11:58 AM   #1
jared_wiesner
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Proper Diagnostic proceedure for E46 Electric Fan

Before you all scream search, I've searched high and low for a way to diagnose a failed electric fan. Not a single thread I've found has a resolution. Given that these fans aren't cheap and I've come across more then a few threads where the OP bought a new fan just to find that it still didn't work, I want to make sure I get the diagnosis right the first time.

Recently I started noticing engine temps creeping up at idle as well as loss of A/C performance at idle. Checked everything out and found that my electric engine fan is not turning on, not with a/c on, not with the engine moving towards over-heating, it won't turn on.
The car is a manual and only has one puller fan behind the rad between it and the engine.

I know the fans receive a constant supply of 12V and get a PWM signal to the third wire to tell the fan control what to do. I am getting 12V of power to the fan, I also haven't come across a broken fuse, though i could have missed one, at this point, that's all I know. Do any of you have any quick and easy ways to sort out if the fan is lacking input or if its just broken?
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Old 06-20-2012, 10:39 PM   #2
abefroman
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I'm having the same issue
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Old 06-21-2012, 08:09 AM   #3
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Well it doesn't seem like anyone knows or is willing to help if they do.
Given that, this is what I settled on. The fan should come on if a/c is turned on, or if the engine is getting hot. They are triggers from two different sources and should rule out any faulty sensors being the problem. If it's not turning on under either of these circumstances, but you are getting 12 volts to the fan, then its the fan assembly (likely the fault is in the control unit).

I've ordered a fan from pelican that should be here next week. My fingers are crossed.
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Old 06-23-2012, 07:50 AM   #4
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How much did you pay for the fan ? I'm having the same issue
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Old 06-23-2012, 08:39 AM   #5
jared_wiesner
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I think 260ish plus shipping from pelican
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Old 06-27-2012, 01:31 PM   #6
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Replaced fan, problem solved...
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Old 06-27-2012, 01:37 PM   #7
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I have the same fken problem and Ive ordered new fan from supernation. I will put it on tonight and see what thw outcome is..

Only cost me 144.

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Old 06-28-2012, 06:57 PM   #8
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Just ran into this problem. I have INPA/EDIABAS at my fingertips, so if anybody knows what to look for, please let me know.

I've tried searching under most of the engine sensors and haven't found it anywhere. Any other ideas? thanks!
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Old 06-28-2012, 07:48 PM   #9
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as a bit of an update, i pulled this engine code after the car overheated:
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Old 06-28-2012, 10:35 PM   #10
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Is anyone able to verify that the diagnostic method I used is sound? If you have verified that fan does not run when engine is hot, then simply turn on A/C. If you don't get fan within a few moments, it needs a new one.
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Old 06-29-2012, 02:27 PM   #11
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well interestingly enough, banging on the relay with a screwdriver started the fan. after reseating the connection it would usually start right up. going to try some contact cleaner
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Old 07-04-2012, 03:55 AM   #12
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You can pull the connector from the coolant temp sensor in the lower radiator hose and the fan supposedly starts on MS42 management. This process worked on my '99 328i when the fan controller crapped out. I ended up replacing my fan with a $158 shipped unit from eBay that has done the job for the past year.
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Old 07-08-2012, 12:01 AM   #13
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I had this problem as well. Bought a new behr fan for an electric fan conversion and it never worked. I assumed my fan was functional, but found out the hard way when noticing my car was starting to overheat. Replaced it with the bosch and it worked right away.

I used relatively the same diagnostic method you did - bosch turned on when necessary but the behr didn't. After removing the behr fan and comparing it to a new bosch, I noticed that the behr fan had much more resistance when spinning the fan by hand - it barely spun and required a lot of force to do so(frozen motor). When installing the behr for the first time i noticed the resistance and thought it was odd. It was probably just a faulty fan from the beginning in my case. It may sound overly simple, but take out your fan and test its resistance when spinning the blades by hand. It should spin with little to no resistance, but if there is a lot of resistance it is faulty.
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Old 08-30-2012, 12:23 PM   #14
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Quote:
Originally Posted by pr0craztinazn View Post
You can pull the connector from the coolant temp sensor in the lower radiator hose and the fan supposedly starts on MS42 management. This process worked on my '99 328i when the fan controller crapped out. I ended up replacing my fan with a $158 shipped unit from eBay that has done the job for the past year.
what is MS42 management? Im trying to figure out if my coolant temp sensor or thermostat is broke. My fan only kicks on when AC comes on but does not come on when the car is hot.

what exactly does disconnecting the coolant temp sensor do as a test? What are you trying to prove or make happen?
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Old 08-30-2012, 12:51 PM   #15
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Originally Posted by Mesa3077Boogie View Post
what is MS42 management? Im trying to figure out if my coolant temp sensor or thermostat is broke. My fan only kicks on when AC comes on but does not come on when the car is hot.

what exactly does disconnecting the coolant temp sensor do as a test? What are you trying to prove or make happen?
MS42 is the computer in a 99-00 (or maybe 01?) E46

Likely doesn't matter as the theory should apply to MS43 as well.

Basically if the computer isn't getting feed from the temp sensor it will just turn the fan on automatically. (It proves the fan is functional if this works and that the problem is before the fan... likely the temp sensor.)
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Old 08-30-2012, 01:38 PM   #16
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Originally Posted by jared_wiesner View Post
MS42 is the computer in a 99-00 (or maybe 01?) E46

Likely doesn't matter as the theory should apply to MS43 as well.

Basically if the computer isn't getting feed from the temp sensor it will just turn the fan on automatically. (It proves the fan is functional if this works and that the problem is before the fan... likely the temp sensor.)
ok i see you responded to my last posts as well and thank you for that!

So this approach is only for the 99-00 models correct? Im a June 2003 model.

thanks for this info. So would it be smart to run the car with the temp sensor unplugged so that the fan just stays on and I dont have to worry about overheating in the mean time until I can narrow down some other avenues?


Thanks!


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Last edited by Mesa3077Boogie; 08-30-2012 at 01:40 PM.
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Old 08-30-2012, 02:28 PM   #17
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No problem.

Should work on all E46's regardless of year. You could do that but the car will not run as well as if It knows the temp. Better bet would be to run with A/C on, if the a/c will get the fan to kick on, (it should). Chances are your fan is done and you need a new one anyway. This is just a way to test that.
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Old 08-30-2012, 03:00 PM   #18
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No problem.

Should work on all E46's regardless of year. You could do that but the car will not run as well as if It knows the temp. Better bet would be to run with A/C on, if the a/c will get the fan to kick on, (it should). Chances are your fan is done and you need a new one anyway. This is just a way to test that.
Ok I get ya. This is a BRAND NEW FAN, just installed yesterday. The old fan was doing the same exact thing. I though it was running intermittently and thought the "speed controller/relay" was bad.

When I was testing my fan I bypassed the speed controller/relay (if thats what you call it) that is attached to the fan, and tested the fan motor direct with 12V and it did work. That lead me to believe that the speed controller that is attached to the fan was bad.

However, the new fan is performing the same way which leads me to believer that the problem lies elsewhere.

I have all this posted in another thread but I figured I would lurk here too to see if you guys had any suggestions..

thanks
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Old 08-30-2012, 03:06 PM   #19
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Hate to OT this. I see your in STL, I'm hosting a mini meet/bbq at my house in Ofallon mo. (burb) you are welcome to bring your car out, meet the crew. I will be grilling FREE FOOD! (first come,first serve) My fan is kinda messed up too. I'm going to try to retro fit some fan into the oem housing, will wire a switch to the dash. If interested in coming out drop me a txt at 989 666 six4six9 jay
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Old 08-30-2012, 03:08 PM   #20
jared_wiesner
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Ok I get ya. This is a BRAND NEW FAN, just installed yesterday. The old fan was doing the same exact thing. I though it was running intermittently and thought the "speed controller/relay" was bad.

When I was testing my fan I bypassed the speed controller/relay (if thats what you call it) that is attached to the fan, and tested the fan motor direct with 12V and it did work. That lead me to believe that the speed controller that is attached to the fan was bad.

However, the new fan is performing the same way which leads me to believer that the problem lies elsewhere.

I have all this posted in another thread but I figured I would lurk here too to see if you guys had any suggestions..

thanks
Gotcha, ya could be the temp sensor then or something else.
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