intermitent power to ECM

Wiring Diagram or tips?
My lumina has been running in limp home mode or open loop. Last week and a few befor my ECM wasn't getting any voltage. The ECM seems fine and so is the fuse. This week is was fine for a day--voltage was back. My buddy told me there are 3 power wires to the ECM, but he doesn't know where it is or have a wiring diagram. Anyone have an IDEA?

Have you made sure you don't have battery terminal corrosion? Have you check the output of the alternator? That is where I would start

We had it connected to an output computer to check the status of everything. power to ECM was most evident problem. What do you suggest if battery/ alt aren't the problem?

Intermitant power problems point to corroded or broken wires. Beyond that, trace the power wires going into the car. Is you battery staying charged or are you having to jump start the car? If you keep having to jump start your car, remove and clean the battery terminals and connectors. You can pick up a tool which does an excellent job for about $5.