HI,
The TPU asserts and de-asserts the ignition control output. It also monitors the ignition control, verifying that there is no external short (it may also look at timing to ensure there isn't too much loading).

I don't have all the answers here... yet but the pins involved on the TPU are 7, 8 and 9. Pin 7 is the monitor. I believe 8 and 9 control the output with one being "limp mode" and the other normally used to fire the coil. I don't have an ICM to check the function however it looks to me like it is just a switch. It is external to the PCM for maintenance and thermal reasons. Perhaps you can answer- is the ICM just a switch with certain limiting built in? This is what I expect.

I need to read the thread before I get further into the ignition control of the TPU.

-Tom