C320 Fan not working

I wanted to reach out for help regarding the fan on my C320 not working. Here's some of the steps I followed so far:
-Checked all pins of the fan connector.
*Permanent 12V OK
*Ground OK
*12v Under contact OK
*ECU Green/Blue cable - moves between 0.3 and 0.5 V when I have aircon on - I assume its working fine
-If I disconnect the connector while the car is on, I get an error on he dash, so I assume its communicating to the ECU
After going through these checks, I assumed the fan motor was not working and I bought and installed a used tested one - Still same issue
For testing, I turn the car on and the aircon to the max in cold. As far as I understand the fan should start working almost instantly but it never does.
As a side note (not sure if it's related) I found a cable that is not connected to anything to the right of the battery bay. Any clue on what this cable is?
Thanks a lot!


