Quote:
Originally Posted by NC_John
I don't think the gen III is smart enough to recognize anything more than +12V or ground. That article I posted the link to has me wondering if I should try switching positive 12V to the pcm for the AC request signal instead of the switched ground I tried that the pcm didn't see (through a Tech 2). I'm just nervous about sending 12V that it doesn't want to see and hurting the pcm. The schematic I am using as a reference shows ground but its a 3rd party schematic and not from GM. I can't seem to get a definitive answer anywhere.
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Circling back, again.
I went through the hassle yesterday of changing the switched ground to AC request to a switched +12V signal. I confirmed its operation through multiple tests with a multimeter. When the ac compressor engaged, the pcm got a 12V signal.
Unfortunately, as seen though a GM Tech 2, the pcm did NOT see (or acknowledge) it as an AC request.
Maybe something has to be turned on through HP Tuners but I'm giving up on this for now. I wish I understood the logic in how the system turns on the AC (how all the inputs and outputs work together) but there are too many gaps in the information available for me to figure it out.