PWM cooling fan(s) control using ECM

[andrewb70]

Originally Posted by 4wheels

Some of the service information for the 2016 CTS-V, ATS-V and Camaro refer to a fan controller but the controller is integral to the fan itself so the ECM is sending the control signal directly to the fan. No separate/serviceable controller exists as the DC brushless (BLDC) controller is built into the fan.

So is the fan looking for a PWM- signal at the same 128Hz?

Andrew

[4wheels]

Most of the fan controllers accept a fairly wide frequency range sp I wouldn't be surprised if all of the GM applications being discussed would operate correctly at 100 to 128 hz. You do have to be careful as to what the expected duty cycle is. What is maximum speed on one variable speed fan (or pump) can be off or an error mode with another.

Some fans also have different polarity of the signal, causing the desired fan control logic to be swapped (maximum speed vs minimum speed).

Originally Posted by andrewb70

So is the fan looking for a PWM- signal at the same 128Hz?

Andrew