PWM cooling fan(s) control using ECM

[Lous69]

Dave,

When my GM PWM fan modules arrive I am going to play with them on the test bench to learn more about how they work and respond to various input signals.

Thanks to you, I know I need to provide them with a 128 Hz PWM signal which will be no problem.

I can measure the impedence of the module when it arrives but I don't know how to determine what voltage range of PWM signal it will be looking for

Do you happen to know what voltage the module is looking for in the input signal it receives from the E67 ECM?

Thank you so much for your knowledge. You are the Man!

[mikels]

Originally Posted by Lous69

Do you happen to know what voltage the module is looking for in the input signal it receives from the E67 ECM?

ECM signal is switching to ground - not voltage.

Most output functions of ECM are that way: injectors, coils, etc. Ground signal is switched with power supplied directly to device.

[parsonsj]

Originally Posted by Dave

Most output functions of ECM are that way: injectors, coils, etc. Ground signal is switched with power supplied directly to device.

One notable exception: fuel pump. That's a 12V signal.