So is that what has caused my headache? What’s the different between the 2… is the first one discontinued?

Thanks for all your help:D

Hold on now. I never said that was your problem, it don't work like thatfor anyone that actually repairs cars. That is the module to talk to, it just happens to have something in common with your issues so that is where to begin testing. As I said before the first thing to do is to talk to it and see what it has to say.

Got it! So how do I talk to it to see if it's functioning properly? I took it out and everything on the circuit board looks good. How do I know if it's getting power or not?

You take the diagnostic computer and go to the EIS controller. There under actual values you will see the modules coded to the CAN B (interior CAN). You will then look at the inventory of modules reporting. This will tell you if the module is at home. If it is then you go to the Body section and pick out the OCM and communicate with it. If communications takes place you will have the oportunity to check for fault codes, actual values, and adaptations.

If it tells you every thing is OK then you have to get your wiring diagram and evaluate each circuit for what you expect from it.

If it don't talk then you need to verify that it is powered and grounded and that the CAN circuit is available. That is a little more complicated.

For more about that you can get a good description here:

http://www.mercedestechstore.com/pdfs/507%20Systems%20I/507%20HO%20CAN%20B%20(ICC)%2010-28-02.pdf

Great info Steve thanks!
Now where can I get an adapter to connect my computer to the car and where do I (if I can) get the utility to run the diagnostic?

Thanks again!