Is there a cheat sheet for the 'Fan Type' settings?

I'm trying to puzzle out what each fan type setting does because the better I understand it, the better I will know what my fan options are and which I like best.

This is an E40 in case the internal logic changes between ECMs (I wouldn't be surprised).

Is there a cheat sheet that describes what each Fan Type setting does in the ECM? Like, low side driver, high side driver, 5v or 12v, pull up/down resistors, and the duty-cycle-to-Desired relationship? I think, from reading the service manuals, that the DC vs Desired thing is reversed between PWM EV (which the C7 brushless fan uses) and PWM Electric (which the C6 fan controller uses), but I'm not sure yet. Any help?

What Vehicle are you looking at the E40 in for the fans?

2006 Envoy 5.3L. PWM EV fan, ECM C1 pin 36 to a SSR. I have tried to measure the signal to the SSR while commanding various settings in the scanner, but a 2Hz signal is about impossible to get a reliable duty cycle reading from with only a multimeter (Fluke 87).

I am comparing diagrams for:
2006 Envoy (E40, single EV fan, C1 pin 36, diagram shows a low side driver in the ECU but the control side of the SSR doesn't make sense, it has two grounds for the signal)
2006 GTO (E40, discrete dual fans, C1 pins 36/56, low side drivers, obviously)
2005 Vette (E40, single PWM Electric fan, C1 pin 36, diagram shows it as a low side driver)
I am also interested in the C7 Vette brushless fan. I don't have a wiring diagram for that one. I do have a stock tune from the repository that shows settings of PWM EV @ 100Hz.

I know the convenient answer is "just copy the settings from whatever you want to use and see if it works", but...

With the GTO, it's weird LOL
this thread explains the GTO fans:
https://forum.hptuners.com/showthrea...r-lack-thereof

Check this out as well. Has all the definitions

http://www.hptuners.com/help/vcm_edi...ystem_fans.htm

So, there is no cheat sheet? Am I weird for wanting to understand this instead of just following a checklist or buying a ~$800 'kit'?

I got the GTO/LS1 dual fans figured out, that's simple grounds that activate relays. Series wired for low speed and parallel for high. No issues there. Not really interested in those anyway.

The PWM fans... I suspect, but not sure, that PWM EV logic and PWM Electric logic are the reverse of each other. One is high Fan Desired = low duty cycle, the other is low Fan Desired = high duty cycle. This is the kind of cheat sheet I was looking for.

There are also aftermarket Spal brushless fans, which use a different control logic than the OEM Spal brushless... information is thin on the ground. Their aftermarket fan 'kit' is using a dedicated, stand-alone temp sensor and I haven't found any real details on if it's possible to control those directly with an ECM instead of a sensor.

And then there is PWM MRF. Nowhere have I found anything that explains what that is or what type of fan it uses or even what 'MRF' stands for. My closest guess is 'magneto-resistive fan' but that just makes me think of a cassette player. Who knows.

PWM EV (Electro viscous) and PWM_MRF (magneto rheological fluid) are engine driven PWM controlled fan systems, the PCM controls the "lockup" of the fan clutch. PWM Electric is a PWM controlled electric fan (such as in a corvette). Discrete is relay controlled fans (such as GTO).

EV uses a eletromagnet to control a valve that restricts fluid flow to lockup the fan clutch, MRF uses the magneto rheological fluid to do the same thing.

Here's a wiki article on how MRF works

https://en.wikipedia.org/wiki/Magnetorheological_fluid

Quote:

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Originally Posted by blindsquirrel

low side driver, high side driver, 5v or 12v, pull up/down resistors, and the duty-cycle-to-Desired relationship

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I guess it's oscilloscope time, then? :banghead:

2006 E40, OS 12612557, OEM C7 SPAL fan (84128344), tune settings of PWM Electric, 128hz. Fan operates as designed. 15% Fan Desired equals 15% fan speed equals measured 75% duty cycle, measured 128hz. As Fan Desired goes up fan speed goes up, duty cycle goes down.

https://forum.hptuners.com/attachmen...5&d=1559699043


Now, this C7 fan, when used in the C7 with a E92, uses stock settings of PWM EV and 100hz. Here's what the '06 E40 output looks like with those settings. No other changes:

https://forum.hptuners.com/attachmen...7&d=1559699062


(Yes the fan works, yes I'm happy about that. I just want to understand! I hate mysteries.)

What's going on here with the failure to output a valid signal at PWM EV/100hz, is this an E40 issue, or an issue specific to this OS? Or specific to this ECM/OS combination? And how is the fan able to understand the 'wrong' signal type of PWM Electric/128hz?

What is different, in the waveform output, between PWM EV and PWM Electric?

Quote:

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Originally Posted by Chris@HPTuners

PWM EV (Electro viscous) and PWM_MRF (magneto rheological fluid) are engine driven PWM controlled fan systems, the PCM controls the "lockup" of the fan clutch. PWM Electric is a PWM controlled electric fan (such as in a corvette). Discrete is relay controlled fans (such as GTO).

EV uses a eletromagnet to control a valve that restricts fluid flow to lockup the fan clutch, MRF uses the magneto rheological fluid to do the same thing.

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Ive jumped into most of Blindsquirrels posts trying to get my spal brushless fan to work on my 2018 Chevy colorado...but this thread has me thinking of a new question that maybe chris can answer. Since my oem factory setting is a pwm ev fan, can I just change it to pwm electric and will it send the correct type of signal to the fan?

Just plugging the fan in (and leaving the yellow wire on the pwm fan unused) did nothing. IM attaching my tune (hopefully, I have had a hard time with attachments the last week)Attachment 103389Attachment 103389

PWM_Electric: 100-128Hz, capable of running with engine off, selectable DC ramp rates, RPM resonance-avoiding logic, only operates within a certain duty cycle band, ie 15-90% DC, utilizes open-circuit diagnostic for fault detection

PWM_EV: 2Hz (nominal), only commands fan DC after engine has been running for a calibratable amount of time, utilizes open-circuit diagnostic and sensed-RPM feedback diagnostic for fault detection

PWM_MRF: 20Hz (nominal), engine running only, utilizes open-circuit diagnostic and sensed-RPM feedback diagnostic for fault detection


Key distinction to make....this is a flexible control system. It can control a brushless Spal fan with an internal motor controller because the controller only pays attention to the signal. But the ECM will still fail the fan diagnostic if you have it set to EV or MRF without accessing and disabling diagnostics because the Spal motor controller has an internal 12V pull-up resistor, which the diagnostic sees as a short to power. For a brushless fan with an internal pullup, you might use a Schottky diode in line with the PWM signal to the fan. I haven't tried it yet, but that seems like a solid bet to isolate the 12V in the fan controller. Again, depends on what kind of fan you have....brushed fans will be different.

Quote:

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Originally Posted by smokeshow

PWM_Electric: 100-128Hz, capable of running with engine off, selectable DC ramp rates, RPM resonance-avoiding logic, only operates within a certain duty cycle band, ie 15-90% DC, utilizes open-circuit diagnostic for fault detection

PWM_EV: 2Hz (nominal), only commands fan DC after engine has been running for a calibratable amount of time, utilizes open-circuit diagnostic and sensed-RPM feedback diagnostic for fault detection

PWM_MRF: 20Hz (nominal), engine running only, utilizes open-circuit diagnostic and sensed-RPM feedback diagnostic for fault detection


Key distinction to make....this is a flexible control system. It can control a brushless Spal fan with an internal motor controller because the controller only pays attention to the signal. But the ECM will still fail the fan diagnostic if you have it set to EV or MRF without accessing and disabling diagnostics because the Spal motor controller has an internal 12V pull-up resistor, which the diagnostic sees as a short to power. For a brushless fan with an internal pullup, you might use a Schottky diode in line with the PWM signal to the fan. I haven't tried it yet, but that seems like a solid bet to isolate the 12V in the fan controller. Again, depends on what kind of fan you have....brushed fans will be different.

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Any chance you've tried the diode?

I’m wondering if that is why the hptuner data logger shows the fan as off even when it’s runnjngz

Quote:

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Originally Posted by fifty

I’m wondering if that is why the hptuner data logger shows the fan as off even when it’s runnjngz

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I have another thought on that I'll put on that other thread.