What is the output voltage of the PCM555 to the ignition coils?

Maybe I'm not understanding the question, but the coils are not supplied power through the PCM, they are connected to splice 105 which is energized (12v) when the Main Power Relay is closed.

Thanks, that is my answer.

If I connect to splice 105 will there be a 12 volt , 0 volt on off voltage signal when the engine is running that can be used like a tachometer signal? (The normal ECU tach signal auxiliary connection point provided from the wiring harness is apparently +5 volts/-5 volts which is not suitable for my need.)

Splice 105 will have a constant 12 volt signal. I would suggest getting a MSD DIS Tach Driver, it connects to the coil power circuit (of one individual coil) and monitors current, then converts that to a 12v alternating signal suitable for conventional tachs.