I brought in my mercedez C320 into the dealership several weeks back after the car had a dead battery. When I walked into the dealership, they told me that the seat module was shorted, and that it was drawing from the battery, thus causing it to die. After I picked up my car, another fault showed up in the display indicating that a light went out. A backup light came up so I ignored it, thinking I would fix this when I brought it into my next service. Soon after, my car showed multiple light faults and when I brought this into the dealership again, they noted that, apart from replacing all the lights, my air bag/safety restraint system was also faulted. What is the cause of all these shorts? Is all of the other problems due to the fact that Mercedes did not diagnose the problem the first time?
These problems are not necessarily short circuits. They are electrical problems of some sort but we cannot tell what is really going on, not from your description. Multiple light faults? That tells us nothing.
What we can say is that the service department is expected to return your car to you with its repairs made and no new problems. If they did this and other problems showed up many days later we must assume the new problems are unrelated. So far we cannot determine if the Mercedes service department did anything wrong.
What year car is it? How long have you owned it?
Do you know it’s history?