PWM cooling fan(s) control using ECM

[Z06vette]

I'm not sure that is the case, but I dont know enough about the software to rule that out. On my old setup - 24x LS1, 411 ecm There was an ac wire from the ecm that connected to the compressor 12+ wire. The E38 harness (from same vendor) does not have that feed. I ran the trinary switch on both cars to one of the fan relays. I spliced the trinary with the ecm fan1 trigger wire that goes to the fan relay. On my LS1 setup, this would allow either the trinary signal, or the ecm (via temp) to trigger the fan. It worked well. I wired this car the same way. The E38 was from an LY6 2500, which had a clutch fan. My tuner can command the fans via the laptop and they both run nice & steady. The car is getting some paint touch up right now; I'll revisit this when I get the car back. Thanks for your input. Scott

[vstol]

I too have read all the posts and have a question. I have a LS3/427 with a reprogramed GM ECM from Blue Print Engines. I just purchased a Dewitt radiator with dual Spal fans. Dewitt says I can not run the fans off the ECM (wire already there from ECM). Not a big deal if I can not but I am not sure why not. Comments? Thanks

[4wheels]

Could you be more specific on what you have (more details)?

What fans do you have from Dewitts. They sell the Spal conventional fans and the DC brushless fans. Control strategy/system is very different depending on which ones you have.

Even with the conventional fans, did they supply the wiring harness? If so how do they have them wires (simple ON/OFF control or High/Low speed using relays more like a earlier GM vehicle).

And then how did Blueprint programming the ECM. What did they expect it to be doing?

And what ECM wiring harness configuration do you have?

Originally Posted by vstol

I too have read all the posts and have a question. I have a LS3/427 with a reprogramed GM ECM from Blue Print Engines. I just purchased a Dewitt radiator with dual Spal fans. Dewitt says I can not run the fans off the ECM (wire already there from ECM). Not a big deal if I can not but I am not sure why not. Comments? Thanks

[vstol]

Originally Posted by 4wheels

Could you be more specific on what you have (more details)?

What fans do you have from Dewitts. They sell the Spal conventional fans and the DC brushless fans. Control strategy/system is very different depending on which ones you have.

Even with the conventional fans, did they supply the wiring harness? If so how do they have them wires (simple ON/OFF control or High/Low speed using relays more like a earlier GM vehicle).

And then how did Blueprint programming the ECM. What did they expect it to be doing?

And what ECM wiring harness configuration do you have?

I will get the exact specs but the relays and harness for the dual Spal fans are included with basically a on off switch at 195/175. The ECM for the engine is a GM setup with the power wire from the ECM to the fans. I would think it would work since it would send the power when the temp was reached on the engine. Thanks

[mikels]

Originally Posted by Old66Tiger

I am in the process of gathering all of the parts to set up my fans to run PWM with the use of a AC pressure switch. It will go in line with the trinary and should allow the fans to work on pressure rather than the state of the compressor clutch. I will be posting all of these parts once I get everything figured out.

Unless you are using just an open/closed AC pressure switch in series with trinary, only way to use true AC pressure sensor is to wire to ECM and use it to control fan output based on AC pressure.

GM ECM's actually have an AC clutch output - issue is AC request comes from BCM (body control module) over CAN to ECM then ECM controls compressor. This allows feed-forward control of increased load from AC compressor to be accounted for - preventing RPM sags and droops. Given that most on this site are running V8's with considerable torque reserve (even at idle) usually not an issue without this functionality.

Lacking this capability (integrated BCM), best method is to use Vintage Air (or like) trinary switch to control compressor and AC pressure sensor wired (and calibrated) in ECM to control fans. Not quite OEM, but damn close (and way better than AC on=fan(s) on).

Dave

[Old66Tiger]

Yes, I am putting the GM AC pressure sensor in line with the trinary. I can monitor AC pressures and ramp fan speeds based on pressure. The compressor is controlled separately.

[SlowProgress]

Does anyone know the part numbers for the mating connector on the 2016 CTSV fan. I don't know if it is used other places but figured one of you may know?

[andrewb70]

Originally Posted by SlowProgress

Does anyone know the part numbers for the mating connector on the 2016 CTSV fan. I don't know if it is used other places but figured one of you may know?

Can you post a picture of the fan itself? Is this a 800 watt fan? Presumably a 2016 CTSV uses a PWM controller for that fan...

Andrew

[SlowProgress]

Hey Andrew. Here is a photo from the build thread.



The Fan part number is 23455465. I think others have said it is around 850W at maximum, so around 70A roughly. I am sure there are other connectors out there but I was sort of hoping to find this one.

[samckitt]

Is this it?