It is in the area behind the driver's headlamp. There is a horn for the alarm that is attatched to a bracket near the ABS pump. If you take off the horn, you will be able to see the resistor.
What I find most is that the wire going to the resistor is fautly too. It can't take the heat. We replace the whole wire with a new one.
ASE CERTIFIED MASTER AUTO TECHNICIAN
MERCEDES SPECIALIST 11 YRS