After searching for a long time, I found a way to check the 4matic light. You need 2 wires and 2 abled bodies would be best.
One wire goes connected/inserted to the #1 hole/connector and the other wire goes to #5. Make sure they are all the way in and are making good contact. These wires would be insterted to the "box" near the battery compartment of a W124. I do not know if this applies to any other MB's and do not know the actual name for this box. Perhaps it is called diagnostic box or who knows.
Turn on the engine and let run for a few seconds. Have your helper/you, place both wires together and make contact for 2-3 seconds MAX. You or the other person look at the dash and count the number of flashes of the diagnostic 4matic light. And voila, your codes are there for you. Now the part I have Not figured out...the damn codes. I have a code: 10, but do not have a clue what it means. Still searching but no luck.
Does any one know the codes?
Thanks.