PWM cooling fan(s) control using ECM

[erick_e]

Originally Posted by andrewb70

It seems that Spal makes various components to make this fan operate in PWM mode without using any sort of ECU, is that right?

Andrew

Yes, they make a temperature sensor which controls the fan, but I still want to be able to control it using my ECU and tune.

I had a decent email conversation with SPAL tech support today. He informed me that there are only three wires going to the fan pos/neg/pwm. The yellow analog/override wire shown in the one schematic isn't actually present on the fan and that I need to use their white pwm wire to tell the fan how fast to run.

I told him I had the ability to adjust the pwm frequency and duty cycle in my ECU and he provided me with this response curve, but I still don't know how to make it work.




So now the question is what how do I use their pwm wire with my ECU.

He said 128 Hz should be ok, but if I really want to change it 100Hz would be the optimal.

Can I just change my PWM frequency in my ECU to 100 Hz and connect the green pwm fan controller wire to the white pwm fan wire?

[andrewb70]

What ECU are you using?

Andrew

[erick_e]

Originally Posted by andrewb70

What ECU are you using?

Andrew

It's an E38. 2009 Corvette Z06 with E-Force.

[carbuff]

Originally Posted by erick_e

He informed me that there are only three wires going to the fan pos/neg/pwm. The yellow analog/override wire shown in the one schematic isn't actually present on the fan and that I need to use their white pwm wire to tell the fan how fast to run.

Ok, that makes much more sense to me. I was scratching my head as to what that wire was for. It didn't go anywhere else in the schematic.

Given the chart you have, I think there is a good chance that you could just connect the PWM wire of the fan directly to your ecu. It seems from your description and the schematics/datasheet that it may very well work. I can come up with a few reasons why it might not, but without having a setup to try and some tools to measure it, I can't say for sure.

From the graph you posted, there is nothing which indicates what frequency the Spal wants to receive natively. It shouldn't really matter that much, you will be off a little bit if your frequencies aren't exactly matching. But you can adjust your settings to get it to run and it will still cool.

I'd try it.