There's no communication between the ECU and the vehicle I'm trying to find the underhood OBD2 connector
where is the underhood OBD2 connector in my car
What year is your CL? The 2002 and older models had a 38 pin connector on the driver side, at the front of the brake booster.
Yours is probabily newer and will not have it.
I would say on the OBD-II port make sure there is ground. I had a C class one time that we could not connect to the ECU. It turned out the ground pin 4 had a short. We simply connected pin 4 to ground and were able to communicate with the ECU.
The pins you want to check are pin 16 for +12 volt.
Pin 4 and 5 for ground (-).
So there is not under the hood OBD port 2001 Mercedes Benz CL500
Not on yours.