The first place I looked. Fuse was good and I have voltage at the AAC valve. The ground to the AAC is controlled by the ecu via pulse width modulation. I've verified continuity between ecu connector and aac connector. I've proven the AAC works by connecting it directly to battery which caused the idle to raise a few hundred Rpms. I cannot however get any change in idle rpm when changing the AAC duty cycle via datascan. Also plugging in/un-plugging AAC connector has no effect on idle. I am almost certain the ecu is the problem. Need a loaner ecu with 740 program to test or an oscilloscope to examine signal...any help from a local?