"S300 board" CN3/CN5 Connectors Possible TTL/GPIO Ports

[civicbynature]

I'm looking at external data-log display possibilities. Could anyone explain what the CN3/CN5 pins on top of the S300 board are for. I know the CN2 pins used on the Ecu are used by the S300 and that as least this pin on the Ecu Uses TTL So The PIC microcontroller at least at this point is using ttL. The CN5 Pins at first glance Look like there Just for Updating the pic firmware Which I have no intention on touching Unless I can also do a data grab from here. But what are The CN3 Pins for? Can These be used For GPIO's.

[Hondata]

For programming the PLC. Can't be used.