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Old 07-17-2010, 03:36 PM   #1
J-SON
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1999 323i Aux Fan Issue - Technical answers needed

I have been trying to avoid this,but I have exhausted my not making a new thread options. I have found several threads pertaining to failed aux fans on the E46 323i manual trans vehicles, but none have any pertinant information in them besides, "replace this and replace that." I was dumb enough to purchase a new aux fan, but pulled my head from my ass when i realized there was another potential issue before I installed it.

The Heart of the issue:1999 BMW 323i 5-Speed Manual

I have a new Aux Fan unit which does not fix the problem of the fan not turning on. I have checked over the normal culprits i.e. the WP the T-stat, but these are working accordingly. I do have power and ground to the aux fan, but what i really want to know is:

-What is the Aux fan signal wire signal supposed to look like (in hz or volts - have read spec is between 10-100hz)
-What is the proper test procedure for the coolant temp sensor located in the lower radiator hose. (cannot find resistance/operation information)
-What is the possibility that the Engine Computer is to blame
-If the coolant temp sensor is in fact bad will it prevent the fan from working at all even if the A/C is turned on.

As it sits right now I have good power and good ground, but no fan regardless of the A/C on or if the coolant temp rises above "acceptable" (approx 230 deg F). The fan will also not turn on to run it's preliminary fan test. The radiator is also in good shape and flows well. I will note that the vehicle will cool off once you are moving (even slowly) or if you rig the aux fan to stay on permanantly.

Any insight would be greatly appreciated! Thank you in advance!
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Old 07-17-2010, 04:58 PM   #2
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Old 07-17-2010, 09:01 PM   #3
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To the top for the night crew!
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Old 07-17-2010, 10:44 PM   #4
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Old 07-17-2010, 11:07 PM   #5
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What do you mean you "have power" to the fan?

The first thing I would do is determine whether the fan is actually receiving power in the first place. That will tell you whether the problem is the fan or the electronics leading to the fan.

I don't know much about the e46's multi-stage fan controller, but I'd imagine that if your idling with the ac on, you should be seeing power at the fan. The e36 used a couple of different windings in the motor to achieve two speeds; each winding would get 12V, low speed was one winding, high speed used both.

Can someone chime in about the e46? Seems like there's a bunch of speeds, so maybe just one winding at multiple voltages is used.

Anyway, rule out the motor before you start getting deep into ECUs.
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Old 07-17-2010, 11:45 PM   #6
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I meant I have power to the plug going to the fan controller, not the fan itself. I guess I wouldn't have a problem then, lol!
Look at the system like you have run a +12V, a GND, and a signal wire(that is supposed to signal between 10-100hz) directly to the front of the car where the fan and controller are. No relays, just a fuse. That controller receives the signal from the ECM which derives that signal from the temp sender on the lower hose and the signal from the A/C high side sensor. I think I may have an ECM problem, but to rule out any other problems (broken wires, or bad sensors) I want to know for sure the resistance range for the temperature sensor on the lower radiator hose before I throw some more $$ at it.
I suppose I can just get it and do it anyway, but I could use that $30 toward the purchase of a couple relays and a 3 stage temp sender(laying in my buddys E30 graveyard) from an E30, lol. Or even wire up a Flex-A-Lite unit instead.
Thanks for the reply! Let's bounce some more ideas!
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Old 07-18-2010, 02:07 AM   #7
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If the A/C's on and sufficiently charged the fan should come on, eventually.

The signal wire's difficult to check but in this case you may not have a choice.

Here's an excerpt from a training manual:

"The electric cooling fan is controlled by the ECM. The ECM uses a remote power output final stage (mounted on the fan housing). The power output stage receives power from a 50 amp fuse (E46 - located in glove box above the fuse bracket). The electric fan is controlled by a pulse width modulated signal from the ECM.

The fan is activated based on the ECM calculation (sensing ratio) of:

-Coolant outlet temperature
-Calculated (by the ECM) catalyst temperature
-Vehicle speed
-Battery voltage
-Air Conditioning pressure (calculated by IHKA and sent via the K-Bus to the ECM)

After the initial test has been performed, the fan is brought up to the specified operating speed. At 10% (sensing ratio) the fan funs at 1/3 speed. At a sensing ratio of between 90-95% the fan is running at maximum speed. Below 10% r above 95% the fan is stationary.

The sensing ratio is suppressed by a hysteresis function, this prevents speed fluctuation. When the A/C is switched on, the electric fan is not immediately activated."

This may not help much, but hopefully it'll give you some idea of what you're dealing with.
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Old 07-18-2010, 04:12 AM   #8
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As I said in your other thread, you want to find someone with INPA or DIS and then go ahead an try to turn the fan on manually. If that works, I'd suspect the DME. If it doesn't, I'd suspect the wiring. INPA is a factory tool, which means you'd have to find (someone with) a pirated copy. DIS is the dealer tool, which means if you can make friends with your dealer (or well equipped indy shop) and get some info.

I'd double check that the lower hose sensor is working and that there isn't air in your system. I don't know the resistance to temperature mapping, but you can pull the values from DIS or INPA pretty easily. I'm not sure which temp sensor the instrument cluster will use for its 'hidden' display, but I suspect it's the one in the head.
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Old 07-18-2010, 11:21 AM   #9
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I'll have to see if I can pull a favor from my friend at the dealer, but I wonder if my father in laws Solus scanner will read these values or if it needs to be specifically BMW tools.

I'm skeptical that there is air in the system, but I suppose it's always possible. The last time I had the cooling system was about 1.5 yrs ago. Recently however I just removed the water pump and "refilled" the system to the best of my ability given my frustration level, lol. The lower hose is warm, but I'm going to go ahead and redo the bleed procedure anyway because I am not convinced it's all set to go yet.

I found this company when I did a quick search for inpa tools. It looks to be a pretty useful little deal and it's only $140. Or I can just get the plugs and find some pirated software.

http://www.easy-motorcycle.com/index...W+INPA&x=0&y=0
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Old 07-18-2010, 04:53 PM   #10
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Are you 100% sure the fan works by putting 12v directly to the wires coming out of the motor? I'm going through this now too. I know it is my fan that's no good because it was making weird noises for a while before it stopped working, and when I tried putting 12v to it, it won't spin. So, driving around now with no fan installed, with new one coming this week.
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Old 07-18-2010, 04:57 PM   #11
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Yeah with INPA or DIS you'll need the BMW diagnostic head or a Chinese knockoff (or similar). There are other more BMW specific aftermarket tools as well. Or you could get creative. Dig through the wiring diagrams and then poke around under the hood and look for a short. Find something to generate a PWM signal and see if you can get the fan started.

I'm gonna partially retract what I said above, from looking at DIS it looks like it and INPA are merely telling the DME to turn the fan on. If you can turn the fan on with DIS or INPA (or similar) you probably have a bad DME input somewhere. OTOH, if you can't, the DME may be bad (less likely)... or the wiring (more likely).
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Old 07-18-2010, 04:58 PM   #12
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Are you 100% sure the fan works by putting 12v directly to the wires coming out of the motor? I'm going through this now too. I know it is my fan that's no good because it was making weird noises for a while before it stopped working, and when I tried putting 12v to it, it won't spin. So, driving around now with no fan installed, with new one coming this week.
If you do that, make sure you're bypassing the fan controller. The fan controller will ignore PWM signals below 10% and above 95% or so. Putting 12V to the fan controller won't turn the fan on.
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Old 07-18-2010, 05:42 PM   #13
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Originally Posted by iclimb513 View Post
Are you 100% sure the fan works by putting 12v directly to the wires coming out of the motor? I'm going through this now too. I know it is my fan that's no good because it was making weird noises for a while before it stopped working, and when I tried putting 12v to it, it won't spin. So, driving around now with no fan installed, with new one coming this week.
YEssir, that's the way I'm running it right now. In my case the fan and controller do not seem to be bad, but rather the DME or the wiring. If your fan was making noise then it's most likely the fan/motor dying a slow death. My current setup involves 2 pieces of 10 gauge wire and some solder... and me getting out of the car and going under the hood every time I leave or stop somewhere.

Currently I am having some other issues with the car that I am noticing as well which leads me to believe there are greater issues here. I have an alternator whine in my speakers and my gauge cluster basically freaks out sometimes when I turn on the headlamps. I should note that there are HIDs on the low beams and capacitors do not stop the cluster from freaking out. This is actually a new symptom because the HIDs have been in the car for more than 3 years. I am also getting a break wear indicator on the dash even though the brakes are still in very good shape. I believe it may just be time to pull the entire front of the car off and remove the engine, trans, and subframe to follow a few wires around in the engine bay area and freshen up a few hoses and plastic bits.
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Old 07-18-2010, 05:44 PM   #14
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The fan is activated based on the ECM calculation (sensing ratio) of:

-Coolant outlet temperature
-Calculated (by the ECM) catalyst temperature
-Vehicle speed
-Battery voltage
-Air Conditioning pressure (calculated by IHKA and sent via the K-Bus to the ECM)
So, what kind of voltage are you seeing with the car running?
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Old 07-18-2010, 09:02 PM   #15
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If you do that, make sure you're bypassing the fan controller. The fan controller will ignore PWM signals below 10% and above 95% or so. Putting 12V to the fan controller won't turn the fan on.
The fan controller being the box on top of the shroud?
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Old 07-18-2010, 10:12 PM   #16
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Is the battery voltage question for me? If it is then I am seeing about 12.6 with the car not running and about 14.7 with the car running at peak output ~2k rpm.

The Fan controller is on the back of the fan shroud under the plug you connect to it.
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Old 07-19-2010, 08:08 PM   #17
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Has anyone said anything about the rad. outlet temp sensor? May have the answer your looking for? Check to see what the ohms are, and check them against the spec at cold. Just a though. Its on the lower rad hose right next the the pass frame rail.
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Old 07-21-2010, 07:37 PM   #18
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I know where the sensor is but I do not know what the cold spec is or the working resistance range for the sensor. What I would like to do is hunt down someone with the GT1 software that I can load onto a VM and get a better look at the DME.
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Old 07-21-2010, 10:19 PM   #19
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Im having the same problem except my fan wont turn off. I have to unplug the fan each time I turn my car off. I'm guessing its the relay to the fan or could it be the coolant temp sensor?
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Old 07-24-2010, 05:34 PM   #20
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Your problem is with the cooling fan itself being shorted out. There are no relays in the cooling fan circuit. Just one measly little fan control wire that goes to the fan control module mounted on the back of the fan shroud just under where you plug it in.

My problem is something very awesome. It seems like there is an open in the fan control wire somewhere. It's shorted out and now i've got to hunt it down. I guess from it being shorted out the fan control circuit in the DME no longer functions... at all. SO I need to find the short circuit and then look for a new/used DME. I pulled a reading from the meter of 3.4 MegaOhms of resistance for that circuit. That signal is taking the grand tour of the car before it gets there!
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