u/Educational_Limit308

I acquired an 06 9-3 Aero without a radio. Previous owner said it had an ICM2 that stopped working, so he bought a used ICM3 to replace it. He tried installing it but had no luck. I figured the issue lies with the fact that he didn't marry the EHU to the car. So I broke out my Tech2 to try to install it. I keep getting the same error message, lost communication with the EHU. I ran a BUS test and I have a break just before the ICM. Now I am wondering if the issue was never the EHU, but rather the ICM.

Question for the group, do I need a functioning ICM to be able to marry the EHU to the car? Is that the source of my communication error, or are there multiple gremlins in this system?