Hello, thank you for the add and reading my post.!
​​​​​​i have an 01 cavalier that has always treated me right, till now.

So it this all began one morning after it down poured all night- not sure if related but probably. Turns over, no start.

I get no spark, no fuel, and the computer does not show it's powering up, when I try to scan codes it says error/no communication. ALL of my fuses have power. I have replaced ignition switch, ignition module, battery, BCM, and ECM with nothing helping. I can jump the fuel pump relay and the pump runs.. it just shows no engine light when turn the key to in position and doesn't start. I have cleaned all positive and ground connections I can find. I'm wits end. Please help..I'm hoping there is a common problem I'm missing while searching the internet.

 

Do you have a wiring diagram, or Haynes, Chilton manual for your car? You should be able to access the power terminal to the ECM, and with a test light or voltmeter check for power to it.

 

I can't find a wiring diagram online, maybe I'll have to pick up a Haynes. I used a test light and found power at 2 terminals to the ecm, but without a diagram idk if there should be more or what volts they should have.

 

The ecm shou;ld have battery voltage on it Probably the top two terminals being battery power to it, check it with key on.