Want to integrate 12200411 PCM control of the AC compressor with my vintage air system. The VA system provides ground for the relay coil. Looking at the wiring diagram for a 2002 Corvette it looks like the ac request pin on the PCM is grounded by the ac controller (manual control) however on 2002 camaro schematics it looks like the ac request is switched to +12. Which is correct, or does it depend on the base calibration in the ECM? I'm using Corvette for the ETC.