What section/page are the grounding locations found in the FSM? I can't seem to locate them and I am looking in the body electrical system.

i dont know where the hell the grounds end up on the ECU. ihave checked the FSM, been near the ECU many times swapping the ECU for another and such and never seen a ground connected anywhere on the chassis...
and heres the ECU pins for ya!!!

3g 3a 2r on S4 are ground but what ones are the central 5V ground and what one is the 12V ground.

S5 without an airbag:

http://i8.photobucket.com/albums/a47...tsWOAirbag.jpg

The most important ECU ground is the dual black wire that grounds to the top of the engine. It's hidden under the intake manifold.

I've never seen that wire before, but all my cars are S4's though that shouldn't matter, or does it?

All RX-7s have this ground. Generally bolted to the vacuum spider. It's the main ECU ground that not only services the ECU but all the sensors as well.