Smooth cooling fan operation on EVO7 and up with an SM4

[Wroom]

One of the really nice things with the Autronic SM4 is that one is rather free in setting up output signals to be inverted or not, delayed, overridden, PWM or just plain on/off.

The Mitsubishi EVO7 and never has a fan controller that controls the fan rpm´s based on a PWM signal.

Basic support for the cooling fan is just to set up an on/off inverted output. Then the fan will turn on at full speed once and again.

The fan controller will handle the startup of the fan so that it does not draw enormous amounts of current when spinning up.

On the earlier EVO´s, which does not have a fan controller, (EVO6 and back), the fan is a simple two speed fan, that draws lots of current when spinning up.
The EVO6 fan, when going from standstill directly to full speed, will draw up to 56 Ampere start current. Yikes!:eek:

The fan controller on an EVO7 and up will start the fan smoother. But...

To make the fan control even smoother with the SM4, one can set up a GPC table, and generate a PWM output from that table to control the fan. That way one can regulate the fan speed based on, for example coolant temp and wheel speed.

But what is really, really nice, is that you can do as the following example:

Connect the cooling fan control signal to the PWM1 output of the SM4.
Then, in the O/P setup menu, assign PWM1 to FAN1.
Make the output inverted, and set the PWM frequency to 38 Hz.
Then, in the O/P FAN1 menu, set Fan1 on coolant to 86 degrees, and
Fan1 off coolant to 83 degrees. Or whatever you prefer.

VOILA!
Now when the temperature rise just above 83 degrees, the fan will start turning slowly. Like a whisper.
As the temperature rise towards 86 degrees the fan will be running progressively faster, until it runs at full speed at 86 degrees coolant.

Say, isn't that a really nice way to go! :D

[MRMRacing]

Nice way, I think I will need to put the scope on and see how the signal looks like when doing this!
Also this fan controler seems nice in other cars!

[Whoop_ass]

cool thanks for this will try it out...


Wroom when you have a gap i will pm you in helping setting up mu Autronic..
you seem very knowledgeable.

I just found the new autronic forum and there is allot of knowledge on here

[bazeng]

Great tip!!
Thanks for that, I'll have to try that on my car

[DanGT4]

Great tip Wroom, but can the fan be connected directly to the SM4 to do this? Or does it have to run through something else, i.e. is the 'fan controller' an integral part of the ECU? Sorry if this seems a bit thick, I'm only just beginning to learn how to use the functions of the SM4! :o

[Wroom]

The EVO7 and newer has a fan controller in a box mounted on the fan. If contains a transistor drive stage that can take an on/off signal or PWM duty signal.

The SM4 could theoretically drive the fan directly. But the fan must never draw more current than the output pin can supply. Cooling fans draw lots of current when spinning up, so it will require an external driver box.

[02ole]

This is not for fans with only two wires. To use this function the fan needs to have a built in fan speed controller. This fans can have three wires. 12v+ and ground are connected at all times, and the last thin wire need the PWM signal to get the fan running. IF you have this type of fan controller, you can connect sm4 directly to the thin wire on the fan speed controller.

[DanGT4]

Ok, thanks guys, I thought that was probably the case but thought I better ask just to be sure. I've got a 1994 Toyota GT4 so it is just two wires driven off a relay rather than a proper variable speed controller.

[bazeng]

So can I purchase these fan controllers from MITSU and use this with a davies craig fan?

Sounds like a great idea...

[02ole]

you can use fan controllers from many cars. In my case I have used a Volvo fan controller. It looks like its the same controller is used in my 2003 bmw 3 series. Both from Bosch. But the fan controllers i have seen, cant be purchased seperatly. There are 5cm/2inch cables between the controller and the fan, so you can cut the wires and use the controller on another fan.

[bazeng]

02ole,

Can you be more specific with the VOLVO controller, like which vehicle it is out of?

I tried chasing up EVO7-8-9 ones and they seem to be rare.

So its pretty much a 2wire in and 2wire out controller?

[02ole]

they have three wires in, and two out to the fan. The three wires in are= one thick 12v+ constant, one thick ground constant, and one thin signal which makes the fan start with the pwm signal. You can use the controller from volvo v70/s60/s80 from 2000 to 2004. It should look like this:

[bazeng]

Hey 02ole, can i please have those numbers from that Bosch controller? Thanks

[bazeng]

Ok, I just purchased an EVO7 fan module.

Finding the VOLVO one here in AUS was a bit difficult.

The module is only about $100 - $150 here..

[scott warwick]

I work at a volvo dealership and come across these fans and modules often. If anyone wants one just let me know.

[bazeng]

What do they sell for?

[mini-itx]

Ok, thanks guys, I thought that was probably the case but thought I better ask just to be sure. I've got a 1994 Toyota GT4 so it is just two wires driven off a relay rather than a proper variable speed controller.

Thats exactly what I have done for my GT4 as well.
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