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E46 M3 (2001-2006) Engine: S54 - Max Hp: 333 hp at 7,900 rpm / 262 lb/ft at 4,900 rpm
Total Produced: 45,000+ - Years Produced: 2001 to 2006.


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Old Mon, Sep-21-2015, 03:00:09 PM   #11
Drewster
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Default Re: How to (actually) wire up a SPAL fan to the aux controller

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Originally Posted by duracellttu View Post
Either way you look at it, they are both driven by the coolant temp.
Well, yes and no - the DME definitely uses coolant temp, but it also uses:
-Calculated catalyst temp
-Vehicle speed (don't really need a fan at 70mph)
-Battery voltage
-A/C Pressure (calculated)

Watching the signal with an o-scope, even when the car isn't fully warmed up, you can engage the A/C and watch it ramp up to about 50% (which is enough to fire up the main fan's relay).
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Old Mon, Sep-21-2015, 04:01:29 PM   #12
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Default Re: How to (actually) wire up a SPAL fan to the aux controller

Primary factors for the calculation are radiator outlet temp and IHKA request; DME will go with whichever results in a higher speed. If radiator outlet temp sensor is bad, it will use block sensor -10C. And if the IAT temp goes beyond 60C, it will bring the speed up to 60% or so until it drops to 50C.

Speed trumps all the calculations. Above 140km/h, the fan will turn off
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Old Mon, Sep-21-2015, 04:09:18 PM   #13
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Default Re: How to (actually) wire up a SPAL fan to the aux controller

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Originally Posted by terraphantm View Post
Primary factors for the calculation are radiator outlet temp and IHKA request; DME will go with whichever results in a higher speed. If radiator outlet temp sensor is bad, it will use block sensor -10C. And if the IAT temp goes beyond 60C, it will bring the speed up to 60% or so until it drops to 50C.

Speed trumps all the calculations. Above 140km/h, the fan will turn off
Thanks for that insight, Terra!

That kind of logic is why I spent the better part of my weekend trying to get the DME's control in play. Eventually I'll probably add a manual override switch, but with just a switch there's a human risk of forgetting to turn it on, and a push-in thermostatic switch will just run at operating temp, regardless of whether or not the fan is needed (so it just puts almost 30A of continuous load on the alternator). Not to mention, you've just got one more source of failure (switch falls out, fails internally, etc)
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Old Mon, Sep-21-2015, 04:32:34 PM   #14
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Default Re: How to (actually) wire up a SPAL fan to the aux controller

So if I'm reading your circuit correctly, the SPAL fan will either be on or off; no variable speed, right? If you wanted to be variable controlled, I would think you'd have to power it directly off the positive/negative coming out of the controller I think. Or grab a second PWM controller, give it a dedicated +/-, and tap into the existing PWM signal wire.
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Old Mon, Sep-21-2015, 04:40:33 PM   #15
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Default Re: How to (actually) wire up a SPAL fan to the aux controller

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Originally Posted by terraphantm View Post
So if I'm reading your circuit correctly, the SPAL fan will either be on or off; no variable speed, right? If you wanted to be variable controlled, I would think you'd have to power it directly off the positive/negative coming out of the controller I think. Or grab a second PWM controller, give it a dedicated +/-, and tap into the existing PWM signal wire.
Correct. Essentially, once the Aux fan starts seeing about 50% output from its controller, that's enough to engage the Spal fan full blast.

Since the Spal fan pulls almost 30 Amps, I definitely didn't want to add that onto the Aux fan controller.

You would definitely need a secondary brushed motor driver, but then you would need to make sure you tie it properly to the DME's output. Most PWM signals are like this, however what comes out of the DME looks to be backward (i.e. 75% duty cycle is actually 25%)

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Old Mon, Sep-21-2015, 05:01:22 PM   #16
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Default Re: How to (actually) wire up a SPAL fan to the aux controller

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Correct. Essentially, once the Aux fan starts seeing about 50% output from its controller, that's enough to engage the Spal fan full blast.

Since the Spal fan pulls almost 30 Amps, I definitely didn't want to add that onto the Aux fan controller.

You would definitely need a secondary brushed motor driver, but then you would need to make sure you tie it properly to the DME's output. Most PWM signals are like this, however what comes out of the DME looks to be backward (i.e. 75% duty cycle is actually 25%)

Yeah I would definitely grab another Bosch module like the stock one if I wanted a PWM controlled fan. Apparently the Bosch module 1137328684 found in some fords (and mazdas and volvos) is compatible with our PWM signaling scheme.
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Old Mon, Sep-21-2015, 05:09:41 PM   #17
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Default Re: How to (actually) wire up a SPAL fan to the aux controller

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Originally Posted by terraphantm View Post
Yeah I would definitely grab another Bosch module like the stock one if I wanted a PWM controlled fan. Apparently the Bosch module 1137328684 found in some fords (and mazdas and volvos) is compatible with our PWM signaling scheme.
And honestly.. When I got the Spal fan and saw some of the "warnings", I thought the noise would be unbearable. However, I was pleasantly surprised with the volume of the straight-blade Spal fan. It's noticeable.. but I don't think it's any louder than the aux fan itself. I think if I want to tweak where the relay engages, I'll put an RC filter on the PWM signal and have a solid-state relay kick on the fan, that way I can adjust the "trigger" level with a trim-pot. I doubt I'll need to, but that's a project I would have some fun with
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Old Wed, Sep-23-2015, 02:24:00 PM   #18
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Default Re: How to (actually) wire up a SPAL fan to the aux controller

Drove the car in traffic this morning, car did great! Couldn't even hear the straight blade fan with the windows up.
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Old Wed, Sep-23-2015, 02:29:31 PM   #19
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Default Re: How to (actually) wire up a SPAL fan to the aux controller

Good to hear it's working! My car has been parked for last 2 days. Cant wait to get everything installed!

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Old Sat, Sep-26-2015, 03:16:26 AM   #20
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Default Re: How to (actually) wire up a SPAL fan to the aux controller

Finally got it to work. One of the ring terminals included with the relay kit was not making good contact, but after that was replaced, both fans work. I didn't know it was repaired until I was driving down the road and heard the spal fan kicking in. Faint but a happy noise to hear for sure. If I am really reviving on traffic stops, needle does climb near 210 mark, but usually remains around 190 (maybe a little less). Very satisfied with the results!
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Discussing How to (actually) wire up a SPAL fan to the aux controller in the E46 M3 (2001-2006) Forum - Engine: S54 - Max Hp: 333 hp at 7,900 rpm / 262 lb/ft at 4,900 rpm
Total Produced: 45,000+ - Years Produced: 2001 to 2006. at BMW M3 Forum.com (E30 M3 | E36 M3 | E46 M3 | E92 M3 | F80/X)