Here are a new release of my Shutdown controller software, you can get it here:
It monitors pin 4 and 8 and takes different actions to the shutdown sequence, please post your questions here.
I also made a circuit that integrates with the software based on a picprocessor to control my computer power on and also monitor it if it hangs and reboots it, if someone is interested I could post more info on that...
Here is a picture of a prototype, based on PIC 12F629:
Computer power switch
Computer reset switch
Power relay, to control Inverter
Turn ignition key on and Power relay to inverter is activated, after 2 secs the power button is pressed on. Now it waits for signal from comport, if it has not been recieved in 4 minutes it pushes reset button. If it recieves signal from comport it activates amplifiers.
Turn off ignition key it pauses RR (optional) and wait for user defined time to go into shutdown sequence. It also brings up a menu so the user can choose what he wants to do when the ignition is off, for example stay on for X amount of seconds, go into standby/hibernation directly.
Here is a simplified schema