BMW E46 Fanatics Forum banner

1 - 19 of 19 Posts

·
Registered
Joined
·
165 Posts
Discussion Starter #1
Hi guys

My coworker and I are trying to diagnose his electric fan problem. A little info:

His expansion tank had a crack in it and basically over heated his car. In addition we found out that his electric fan didn't work. We applied 12volts directly to the hot lead and shorted the third speed control pin with 12v. This should technically turn on the fan on full blast, but we got nothing.

So we took the old fan out and took out the control board and put 12 V directly onto the fan, it works fine. The fan controller stopped working.

Today we bought another electric fan. It was an aftermarket made in Taiwan. Put it in the car and stopped working again. Verified voltage coming out of harness, about 12V. Not working

We replaced his expansion tank last week.

Any help on this issue would be appreciated. Thanks!
 

·
Registered
Joined
·
271 Posts
According to my materials, if the PWM signal is above 95% on-time, the fan will not spin; so applying 12v to the control pin while providing power/ground to main circuit would not activate the fan. I suppose it's the same for an aftermarket part, but I've never tested it. This information is from a BMW training manual.

To get the fan spinning at full speed I would unplug the refrigerant pressure sensor on the receiver/drier. That is, if I didn't have a DIS or scan tool handy with a component activation function.

I wonder how you know the fan is not working, i.e. what conditions are you expecting it to come on when it doesn't?
 

·
Registered
Joined
·
165 Posts
Discussion Starter #3
According to my materials, if the PWM signal is above 95% on-time, the fan will not spin; so applying 12v to the control pin while providing power/ground to main circuit would not activate the fan. I suppose it's the same for an aftermarket part, but I've never tested it. This information is from a BMW training manual.

To get the fan spinning at full speed I would unplug the refrigerant pressure sensor on the receiver/drier. That is, if I didn't have a DIS or scan tool handy with a component activation function.

I wonder how you know the fan is not working, i.e. what conditions are you expecting it to come on when it doesn't?
Thanks fotsir. Probably has been the most helpful reply so far (posted this question on other forums also). I didn't even think about PWM when I was working on this but it makes a quite of bit of sense. I have a signal generator and will apply a 50% PWM signal at 12 V to day to check it out.

I will also take out the temperature sensor on the radiator hose and short out the pins on the harness (to form a closed circuit) to make sure it is not a problem with the sensor. I tried this yesterday with a 12V DC signal but it didn't work (not PWM).

We believe the fan is not working because it doesn't turn on when the car is idle and the car over heats. I've read elsewhere that the fan should turn on when the AC is running. Tried that also.

If it works with a signal generator, than we know the fan works. I can narrow the problem down to the following:

(1) Temp sensor
(2) A fuse or a relay

If you think it can be something else also, please let me know. Thanks! :hi:
 

·
Registered
Joined
·
366 Posts
i was having the same problem ie: overheating at idle(intermittantly) fan would run(sound like a plane taking off) or not run (make a growly noise) replaced fan with bosch from bmwpartsweb.com for 253.00 + free shipping.

new fan i dont even hear it running unless i stand in front of the car and it has not overheated any since replacing the fan.
 

·
Registered
Joined
·
165 Posts
Discussion Starter #5
Yea we still have no solved this issue. I might check the fuse and relay. I still can't explain why the new fan we installed (aftermarket) worked and stopped working. I am thinking possible over current that might have fried the controller board for the fan.

We are going to try to look at the fuses and relays to see if any of them are burned out.
 

·
// Quandt AG (Retired) //
Joined
·
3,700 Posts

·
Here to serve y’all
2004 330Ci 85k miles
Joined
·
11,086 Posts
Yea we still have no solved this issue. I might check the fuse and relay. I still can't explain why the new fan we installed (aftermarket) worked and stopped working. I am thinking possible over current that might have fried the controller board for the fan.

We are going to try to look at the fuses and relays to see if any of them are burned out.
Was the aftermarket fan you installed just the motor and fan blades and connected to the BMW Final Stage Unit? Risky move. That could over-current the fuse or controller board if the motor impedance is different than the original fan motor.

Check the pins for the two large wires in the electrical plug for 12V and a good ground. The supply wire should always have 12V, even with the ignition key off, since the fan may run in that condition.

The third (small) wire gets a PWM signal from the DME that the fan's Final Stage Unit (controller board) uses to control fan speed (converts low current PWM control signal to a high current PWM drive voltage using an amplifier). If you have an oscilloscope, you can measure both the PWM signal at the plug and the PWM drive voltage at the fan motor wires to see if they are correct.

It might be worth it to get a used Final Stage Unit from a junk yard?
 

·
Here to serve y’all
2004 330Ci 85k miles
Joined
·
11,086 Posts
Just to clarify, it is not an aux fan relay (AFR). BMW calls it a Remote Power Final Stage, but it is essentially an active current amplifier. It takes the low-current PWM signal from the DME, amplifies the current, and drives the fan motor with a high-current 12V PWM. It also limits the control range for fan motor protection.

The post that solved it. It was a broken fan control wire.
http://forum.e46fanatics.com/showpost.php?p=12112829&postcount=26
 

·
Registered
Joined
·
3 Posts
2005 BMW 325i electric coolant fan not working

Hi! I am losing my mind...help! I am having fan issues. Realized it is not coming on to cool car when stuck in traffic. It comes on with ac. DME shuts down ac and fan when car gets hot. I have replaced sensor in lower radiator hose 3 times, replaced climate control recirculated air sensor, and electric fan w/shroud. checked fuse and is good. Took to a private BMW shop and he said he had never seen this problem, he hooked up to my car with his hand held scan tool and turned fan on. Fan came on correctly.There were no codes. Tested 2 wires from sensor to computer, tested good. Tested control wire from fan to computer, tested good.12 volts present on control wire. Drops to 10 when ac with fan kicks on.
 

·
Registered
Joined
·
7 Posts
2005 BMW 325i electric coolant fan not working

Hi! I am losing my mind...help! I am having fan issues. Realized it is not coming on to cool car when stuck in traffic. It comes on with ac. DME shuts down ac and fan when car gets hot. I have replaced sensor in lower radiator hose 3 times, replaced climate control recirculated air sensor, and electric fan w/shroud. checked fuse and is good. Took to a private BMW shop and he said he had never seen this problem, he hooked up to my car with his hand held scan tool and turned fan on. Fan came on correctly.There were no codes. Tested 2 wires from sensor to computer, tested good. Tested control wire from fan to computer, tested good.12 volts present on control wire. Drops to 10 when ac with fan kicks on.

Did you get this resolved?

I have similar issue. Fan works fine with ac on, inpa fan test works and I can do 20%/80% etc fan speed test. However auxiliary fan never kicks in at high speed when my cars temp creeping past the half way mark.
I believe the aux fan should kick in when I'm idling and my temp is past 100 degrees. I've had it at 118 degrees without auxiliary fan kicking before I shut engine off.

I did coolant system refresh, so my CTS is about 6 months old. Ive used a Febi sensor.

What should be my next port of call? Advice gratefully received.

Thanks
 

·
Registered
Joined
·
7 Posts
BaliDawg / BMW North thank you both.
BMW North, quick shout out to all your excellent info across the Web. Nonetheless I read the guide and was able to do your recommended INPA test procedure and the auxiliary fan successfully responded to all input speed requests.
Following the above test I ran live temp diagnostics in INPA and was able to determine the following.

I've had INPA plugged in and had the car up to temp for over an hour yesterday evening and much to my surprise the auxiliary fan was kicking in to assist cooling. Over the moon with that.
NB the following. The coolant temp was going up to and above 110C. The coolant outlet temp was managed quite effectively by the auxiliary fan and didn't go above 86C degrees.
Basically when the outlet temp it hit 85C the aux fan kicked in to drop temp to c60C within a minute, and it was doing that for the full hour INPA plugged in. So that's all good.
But the coolant temp (the inlet) kept climbing. So that leads me to two possibilities.
1) viscous fan isn't engaging to cool
2) thermostat isn't working.

So with my engine coolant temp at over 100C and car revved to 3k I was able to stop the Viscous fan quite easily! Using an envelope poked into the fan blades it stopped pretty quickly. I could do it with my fingers!
In theory the Viscous fan should have been engaged and running at some pace. But I don't think it was.

The thermostat I think was working as the outlet temp was fluctuating between 60C-85C so I think that suggests it's opening and closing.

I think that viscous fan isnt doing enough to cool the overall temperature and the aux fan is kicking in to assist but as the outlet temp drops ASAP it's assuming it's job is done and switches off.

So I'm going to replace the Viscous fan coupling and reassess.
 

·
Here to serve y’all
2004 330Ci 85k miles
Joined
·
11,086 Posts
The thermostat I think was working as the outlet temp was fluctuating between 60-85 degrees so I think that suggests it's opening and closing.

I think that viscous fan isnt doing enough to cool the overall temperature and the aux fan is kicking in to assist but as the outlet temp drops ASAP it's assuming it's job is done and switches off.

So I'm going to replace the Viscous fan coupling and reassess.
Are all your temps here Celcius? Maybe mark them going forward to avoid confusion? Most denote temps as 96C or 200F.

Agree that the t-stat appears to be open if you’re seeing coolant flowing through the radiator.
I doubt the air flow, and specifically the fan clutch, are the problem here. The electric fan seems to be reducing coolant temps just fine.

My gut tells me it is coolant flow -- t-stat, water pump, blockage, etc. — but that’s a guess. You’re seeing high temps at the cylinder head temp sensor but reasonable temps at the radiator outlet temp sensor, correct?
 

·
Registered
Joined
·
7 Posts
Are all your temps here Celcius? Maybe mark them going forward to avoid confusion? Most denote temps as 96C or 200F.

Agree that the t-stat appears to be open if you’re seeing coolant flowing through the radiator.
I doubt the air flow, and specifically the fan clutch, are the problem here. The electric fan seems to be reducing coolant temps just fine.

My gut tells me it is coolant flow -- t-stat, water pump, blockage, etc. — but that’s a guess. You’re seeing high temps at the cylinder head temp sensor but reasonable temps at the radiator outlet temp sensor, correct?
Hey BaliDawg,

Apologies all aforementioned numbers are degrees Celcius. Will mark as C going forward.

Good point you make, I'm wondering whether it could do with a drain and bleed. Air pockets could cause issues. I changed the heater core a few weeks ago and I bled (I believe correctly) then, but no harm in doing again.
Tstat and WP have less than 15k miles on I'd say. It's had a change in WP and thermostat and the WP is metal impeller Meyle iteration.
I changed the main radiator to a new nissens one and changed top / bottom hoses for good measure, so blockages should have been resolved by doing so?
ET is an a bmw one, it was date stamped 2013 so had previously been changed again less than 15k miles on it.

Correct high temperatures as cylinder head. Reasonable readings at radiator outlet.
 

·
// Quandt AG (Retired) //
Joined
·
3,700 Posts
On the surface from a scan of the last few responses it sounds like a coolant flow issue. Waterpump or T-stat would be my main focus. What's the history on the WP? A worn viscous fan would still not allow such high tems at ECT as DME would drive the e-fan harder to bring down the temps - which is what it sounds like is happening. - the fan normally switches off at 75C CTS. Remember if you change the viscous fan change the WP at same time - they share the same shaft and any vibration from a bad bearing or wobble transfers to via the shared shaft causing premature wear on the mated part. I have a strong suspicion that your waterpump impeller is not spinning at rotation speed - seen this on a few with viscous fans - it seems to put a beating on the waterpump. Takes a few mins to remove the waterpump and check the impeller.

Edit - just noted that you said WP is <15K - but it's a Meyle - other than a couple of decent bushings I've never trusted their parts. Especially critical cooling components.

Oh and one last thing. There were a few instances over the years of wp's assembled with the impeller on backward. Meaning the coolant was not flowing correctly. Check that too.
 

·
Registered
Joined
·
7 Posts
Thanks for your responses BaliDawg / BMW North.

Makes sense tbf, and as you say since I'll be changing the Viscous fan coupling the fact the fan coupling attaches to the WP would be silly not to given the issues I'm having.
Didn't realise your love for Meyle! The Viscous fan coupling I've ordered is Meyle... :oops:

I appreciate there is a lot of talk RE WP / Tstat brands with alot of conflicting views. If you were changing on your e46 what brand WP / Tstat would you go for? (aside from a Stewart pump). Would also be interested to know what you'd chose other than dealer part if that would be what you're about to suggest!

Back story: I bought my 330ci e46 in Aug/2019, and I had a sagging radiator so I decided to change that alongside checking all the other parts. Whilst doing the maintenance I noticed the WP was Meyle and the Tstat behr (I think). The date stamp was 2013 and based on mileage history that was about 10k miles before I bought it so thought I'll save the £75 (in the UK here) thank you very much.
Looks like a short lived saving! 😅

Much appreciated
 
1 - 19 of 19 Posts
Top