One way to verify if the pcm is functioning is to monitor the 5 volt reference signal when the key is on when the issue is happening. You can use the tps sensor as it is easy to get to.
As far as the relay, it grounds with the key on to send power to the items in the diagram.
There is a diode in the pcm in line with the 12 volt signal as you see. Once it is grounded, it controls a lot of power sources to different items.
Look at the diagram I sent you.
Monday, December 24th, 2012 AT 9:48 PM