[C. Ludwig]

A - ECU signal
B - signal ground (rotor housing)
C - signal ground (rotor housing)
D - primary ground (battery negative)
E - primary power (battery positive)

Pin B is the one that's not real important. The AEM instructions say ECU signal ground, but the rotor housing is fine. It's primary use is for OE mis-fire detection, which we obviously aren't using.

I do wire the Haltech as their instructions say. Power ground to the chassis and signal ground to the battery.