I just stumbled across this:
Request Input
A 12V signal wire is monitored at pin 17 of the red PCM connector. With no voltage applied, the circuit is open and the PCM does not attempt to turn on the A/C compressor clutch. When 12V is applied to the circuit and based on the pressure in the system, the PCM commands the A/C compressor to turn on.
Source is
https://www.lsenginediy.com/upgradin...tioning-guide/
This contradicts the other stuff I've seen and heard though. I have a switched ground going to pin 17 on my green connector. I wonder what the PCM will see/show/do if I send 12V+ instead of the ground...... I'd sure hate to hurt the PCM.