p-car993,

I do remember a website by a Norwegian ( not sure ) in English and amacingly clear and simple about all you would like to know about the working and trouble shooting on a W 124 - 4 Matic.
I printed it out but forgot to arrange so I am not able to find it back quickly.
Try a search by Google under W124 + 4 Matic and hope...
Let me know if you do / don't find it back.

Danny