The PCII worked differently than the PCIII,PCIIIr, and PCIIIUSB.
The PCII received sensor inputs, modified them according to the map info, and then fed them to the ECU.
Essentially the PCII alters the sensor inputs to the ECU to alter injection timing.
This is why the PCII connected directly to the ECU connector(s).
The PCIIIx series works the opposite. It alters the ECU injector timing outputs according to the map info.
It connects between the ECU and the injector harness.
The PCIIIr also added the capability of modifying the ignition timing for each cylinder for race purposed. The 'r' is for Race.
The PCIIIr Red connectors can be interconnected between the Pulse Generator outputs to the PCIIIr, and then on to the ECU.
The PCIIIUSB is an improved PCIII with a modular USB interface that allows optional modules to be connected via the USB bus.
Depending on the bike, it can be a timing module (to act similar to PCIIIr), a quick shifter module, and so on.
The PCIIIUSB also has the capability of having the injector timing sample resolution changed from the default of 250 times/second to 500 times/second for more precise injector tuning.
PCV is only for recent model ECUs that communicate via a CAN (Computer Area Network) bus.
Last edited by SubSailor; 11-23-2011 at 12:44 PM.