I have a 1996 E320 whose alternator was not charging the battery. I ordered and received a voltage regulator from autozone and replace the old one. When I put back the alternator and tried to start the car, no light came on on the instrument cluster and the key turned but no live. I then realized that all the switches, inluding the headlights, turn signal, brake, hor, etc are not working. The only thing that is working is the radio. I then removed the alternator and discovered that though the voltage regulator looked exactly like the old one, there' a variation in the numbers on the VR. I removed it and got another one withe same number and put it on. I tested the alternator and it works fine. I also replaced the battery with a new one, cleaned the cabled, checked all the fuses in the car and found them intact. Yet, the car shows no life except for the radio. Even my mechanics has no clue what could have gone wrong. Any help will be appreciated.

 

Colud it be ECU/ ECM? Can it be pulled out and tested? I have searched this and many other Merceded Benz related forum and the questions similar to mine received no answers, I'm afraid this will die the same death. Any suggestion will be appreciated.