You should check with the vin to see what model it is. Is it a 4 cylinder or a 6? I would suspect that you have a 4 cylinder 2.3 from your above statements.
If so, you don't have a warm up regulator. This was only used in the early models.
You should check the fuse in the top of the over-voltage relay. IF it is OK, I would replace the relay.
We sell the CD for the 201 chasis. IT COVERS THEM ALL!!
ASE CERTIFIED MASTER AUTO TECHNICIAN
MERCEDES SPECIALIST 11 YRS