Maybe there is something in the written software that varies by ECM software version as far as thresholds and/or limits are concerned. Everything flipped for the aftermarket fans doesn't mean anything to the software, but a value that's higher (reversed) certainly may be 'out of parameter' forcing non-expected fan behavior?
Fifty, your fan tables are completely different than mine. You are using an aftermarket fan and it works as expected/factory with reversed values?
The software on a GM fan is different than one of our aftermarket fans. The signal inverting is intentional in that case. GM has their controls and SPAL didn't want other SPAL products to be plug-in-play install into OEM applications. New vehicles have already switched from PWM to LIN. So soon it will be even more difficult to do sweet fan swaps from new vehicles as the fans will use LIN communication. But that also means your fan is reporting RPM, motor temperature, drive state, and much more data back to the vehicle ECU all the time. So they can tell if the fan is windmilling or being powered and always have live data from the fan. They use this information for active aero decisions, kinda neat. We have also been asked by some OEMs if the fan could be powered and the blade intentionally 'held' in place as a method of adding restriction to incoming cold air to increase radiator heat up times in cold weather. We have also been asked if there could be some energy recovery from the fan free wheeling. At this time 'holding' the blade and energy recovery are just pipe dreams, but it's an interesting thought.
The part I don't understand is what is the difference between PWM EV, and PWM Electric. Why sometimes people get it to output on one setting and nothing on the other. I have had people use PWM Electric, and PWM EV because one labeled "FAN PWM" wouldn't output. I fear this changes between different ECU versions, so it's difficult to nail down exactly which version people should be using. I believe some outputs vary in frequency and not in duty cycle. For the fan, the frequency should be constant between 50-500 Hz. Changing the frequency outside of this range would cause the fan not to work. Unfortunately I haven't ever gotten the chance/time to sit down with an E67, and other ECUs, and our scopes and see what the various outputs do.
Yes...Originally Posted by cpd004
As for working? More or less. It’s a spal pwm Fab replacing the stock 2018 Chevy Colorado fan
I've looked at a bunch of stock tunes in the repository across different vehicles. Most PWM Electric are either 100 or 128. Most PWM EV are 2 with a few being 100. I feel that changing the frequency may or may not do anything specifically. For example, this value is changeable, but the internal coding/software is specific.
PWM Electric at either 100 or 128 makes my fan work, but not like it should. PWM EV at 100 does nothing. It doesn't do anything at the default value of 2 either, but it shouldn't. One thing that came to mind is maybe PWM EV uses what would normally be FAN 2 output? or 3 for that matter? This is just throwing things at the wall to see if they stick.
Blindsquirrel, did you happen to check the other outputs?
Last edited by cpd004; 12-16-2020 at 01:02 PM.
My 2018 chevy colorado v6 is a pwm ev on the tune and it is doesnt seem electro viscus but more like an parking brake. It has pads that seem to get pushed out to make the outer housing that the blades are connected to spin.
That would make me think that the fan motor is always spinning at max speed and the power signal simply makes the friction pads push out at different rates to then make the fan blades spin... so its always slipping unless at 100%? The only other option I can think is that when the fan turns on the friction pads immedietly get activated too and then the fan motor is spun at what ever speed is commanded. I dont know.
SO on to the factory tune, its pwm ev, 100 mhz, and then its oem desired% vs ect is 3.99932861328125 3.99932861328125 3.99932861328125 18.0206298828125 24.3515014648438 37.0132446289063 43.3441162109375 49.676513671875 56.0073852539063 67.00439453125 77.9998779296875 82.000732421875 86.99951171875 91.0003662109375 91.0003662109375 91.0003662109375 91.0003662109375
and starts at 212 degrees and tops at 255 degrees
The fan desired vs ac is 3.99932861328125 13.9999389648438 13.9999389648438 13.9999389648438 19.000244140625 19.000244140625 30.0003051757813 35.0006103515625 45.9396362304688 59.7991943359375 69.7006225585938 76.0009765625 80.5007934570313 85.0006103515625 89.5004272460938 91.0003662109375 91.0003662109375
Its weird how the fan is commanded to run so slow when its so hot..... Doestnt hit 50% until 230 degrees.
Definitely a headscratcher. So setting ALL of the outputs (Fan output desired vs Current State) to 0 (zero) should make the PWM wire (Fan 1 wire in discrete) not output anything at all. It doesn't do this. The fan will still operate (come on) at what I am testing it with (199 degrees).
Maybe in discrete, a zero will make the fan off? I don't really care about discrete though.
PWM EV won't make the fan work despite what I've tried.
Fan desired starts at about 84.5 at about 200 ECT (where I'm testing at). As the ECT climbs, this number goes down as it should.
FAN Goes back and forth from 99.6 to 0 every second approximately.
FAN 1 Flashes On Off in relation to FAN. When it is ON, it shows 99.6 and 0 at OFF.
I think PWM EV is what would be needed for an aftermarket Spal brushless fan to work correctly. Something is making it fail though (in the E67?). Maybe there is another input necessary in the ECM that isn't present causing it to fail.
PWM Electric does make the fan come on, but it acts like discrete. It comes on ramping up very quickly before coming back down to 85% (15% oem).
FAN 1 shows ON.
FAN Desired Speed Never shows anything here like it does in PWM EV.
FAN Desired Ramps up to just under 85 when FAN 1 switches from OFF to ON. It is this ramp up that I believe makes the fans start very fast before coming down to a lower RPM. This number goes down to 0, but the fans aren't OFF until FAN drops to 0. I suspect this has to do with the values in the FAN DESIRED % VS ECT table.
FAN Where is this value coming from?
As FAN DESIRED goes to 0, FAN still has value and doesn't get to 0 for another 20 or so degrees. The fans are climbing in speed as this number heads to 0. Once at 0, FAN 1 shows OFF and the fans finally shut off near 181 degrees.
I’m trying to digest everything you have posted there. The last paragraph made me think that box 18040 has something to do with the fan still staying on, even when the temp has been attained.
The 18040 graph looks like a down shift and up shift strategy for an auto transmission. That way when you are holding at a temperature that is in the desired % vs ect, the fan isn’t being triggered on and off, on and off, on and off etc.
So even if the fan is supposed to be at 20% at 200 degrees, it will stay at 20% until it gets down to 194 degrees then change to 10% etc or how ever you have it programmed in the 18040 graph.
I believe I tried it that way as well, and it still didn't work correctly. I understand the transmission shifting strategy, but must be missing something. Unless I have completely wrong values in there. I've even tried all 0's as some have stock in the repository.
Last edited by cpd004; 12-17-2020 at 01:54 PM.
Copying over a 2017 Chevy SS (not Camaro) makes everything work without long fan run on, but all with the fans way too high. This is one of the few times FAN & FAN DESIRED are in sync.
Reversing everything immediately makes it run on for quite some time. This is also when FAN & FAN DESIRED do not sync up. FAN continues on to count back to 0 as FAN DESIRED is already at 0. FAN DESIRED is at 0 at about 199 degrees. FAN is at about 44.5% and begins to descend to 0.
I've tried so many different things and nothing seems to work correctly.
This is one of many, many reverse trials:
PWM Electric just won't work correctly with anything I've tried.
I feel that it would with PWM EV, but I suspect the ECM goes into fault mode due to either feedback or something expected not being present.
smokeshow said a Schottky diode may help in another thread, but no idea if he tried it.
I'd stay away from aftermarket Spal if the desire is to have the ECM control your fan. My goal was modern car quiet and so far nothing I do with the fans I have will accomplish this with the E67.
The solution to all these problems is really simple: If you have the aftermarket fan, use a standalone controller built for it. If you want to control it with the GM ECM, use the OEM GM fan and not the aftermarket fan. Done and everything works as expected.
I am Running two Spal Fans with a E38 , One is a 14" The other is a smaller 12" Fan , The Fan Type Tab is set to Discrete , 128HZ,
My two fan wires from the ECM send a ground signal , I have them each tripping a relay on the ground side of the coil, and ignition on to the coil + side of the relay , Power comes directly from the battery
to the Switched side of the relays , This Powers the fans , If you want your fans to run after the car is shut off for a timed cooled down use Battery power instead of ignition power to the positive + side of the Relay coil , Also you can run a in the cockpit Fan Switch to power your Fan when the car is off, with a 2 legged toggle switch, ground one post to chassis ground and the other to The ECM Fan #1 output wire , But this will only work if you have your coil side of the Fan-1 relay hooked to battery +, if hooked up to ignition Key on you will have to Place your Key switch in the on position, This i wouldn't do , key would have to be left in car and ignition would have to be left in the ON Position,
Hope this helps
Relay-controlled single speed 2-wire SPAL fans work just like any other 2-wire fan. Issues discussed here are only for the 3-wire, variable speed brushless fans with integrated speed controllers.
Got you, i didnt see that, OK then run 2 wire fans, mine works great!
I havent checked here for a very long time but I came back because my SS fan is having issues. I have the the SS 850W fan running puller and the C7 600Watt as a pusher, both using the same signal wire. 3 days ago the SS fan stopped working properly. I noticed that it would do the kick which it normally does when it first wants to start, spin 1 revolution then stop. No idea whats wrong here. The other fan is running as normal. I only realized this issue since the other fan is noisy and it had to run at a higher speed to compensate for the puller not working.
But to give some input here, Brent posted the logic of the Spal fans (GM vs aftermarket) which are opposite to each other. GM uses 0-90 which is AFtermarket 90-0.
With an Oem ecu and the aftermarket version of the fans, the PWM signal sent by the ECU to the fan is done by slowly ramping it up and down. So if you command 90%, its not immediately 90%. on my E67, it takes 10 seconds for the signal sent by the ECU to go from 0% to 90%. This results in a cat & mouse effect during startup (and if you have the fan deactivate at speed option).
For cpd004, when your coolant temp hit 199.4, the ecu starts sending a signal. As it ramps it up, the ECU sends it as 5%,10%,15% ----> 80%, 85% , which the fan interprets inversely as 95%,90%,85% ----> 20%, 15%, and this is why your fan ramps up then slows down (it probably ramps up to 50% speed by the time the ecu is now outputing 50%).
Nothing can be done to solve this on a GM ecu. If you're using a holley ecu I believe, you can actually change the output signal from PWM + to PWM -, which is basically a signal and its inverse.
Thank you! This is likely why it doesn't completely shut off when commanded to do so. It is the same ramping effect in reverse for shut down.
You'd think there would be converter readily available for another use that could possibly work here.
I wish someone could make an inline signal reverser, like the pedal commander, but for pwm.
So it would change the 0-5v to 5v-0
So when it’s getting the oem 0-90 signal it inline reverses it to 90-0
Only way to get the ecu to play fair with the alternator and defroster etc etc etc.
I’m about to give up on running this stiff off the oem ecu with the tune reversed and run a stand alone pwm controller and just put a resistor in the oem wire harness.
Lol, I was just posting that. I wonder why it got frozen in time? Lolz.
An inline like a peda commander. 0-5v in, and 5v-0 out.
You can, google aurdino and you will find it possible. I researched into this and I realised im shit and its just easier to buy a 600 watt salvage C7 fan with a broken shroud (cheaper than a good salvage one), unbolt the motor and blades and swap it into my aftermarket brushless spal fan shroud. If anyone needs a replacement fan motor for a 14" spal aftermarket brushless fan (500 watt) let me know
Now I just need time to troubleshoot my SS fan
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