ECM replacement?

Hello, this is 2010 Cadillac cts sedan 2wd, 3.6liter engine. The ECM is located in the left front of the engine compartment. This diagram should help. Sorry for the 3 diagrams, I'm having trouble erasing 2 of them. But they're all the same.

If you look at the lower picture, notice the arrow, that's pointing forward on the vehicle. So if you're looking at the engine compartment it will be on your left side (passenger side). It's probably under the fuse block. I understand your frustration, we go through the same thing trying to find modules some times. Try following the wire harness, that might help as well. Is there something wrong with the ECM?

Here is a picture of the ECM:

I don't have any previous questions from you. Did you chat with a different Technician?

So is it the compressor that stops running intermittently? You've checked that compressor is actually losing power at the plug on the compressor itself? Do you have auto A/C? Where you can change temperatures on either side differently?

Okay, I see what's going on, you're saying that pin 86 isn't going to ground. That's the pin the ECM grounds to engage the A/C relay. I'm just catching up on what's going on. So you are reading 3v on pin 86?

If you're reading 3v and using the battery as ground, then you're reading voltage drop on that circuit. I see pin 44 dark green/white wire is the ECM pin for the relay. So I'm assuming you're trying to check that pin at the ECM. You're getting only 10volts at pin 85?

From my experience, I'd take a look to the under side of that fuse block in the engine compartment. I bet there's some corroded wires underneath the fuse block. I've seen that many times. Any green corrosion is going to be an issue.