Mercedes W211 E320 CDI — SAM Module Capacitor Repair
The SAM module was unresponsive — power windows and interior lighting had failed. Findings: a defective capacitor on the SAM board. The board was repaired, the original SAM stayed in the vehicle, and no recoding was required.
Vehicle
Mercedes W211 E320 CDI
ECU Family
SAM (Signal Acquisition Module)
Category
Efficiency
Results
Original SAM preserved | No recoding needed | Windows & lighting restored
Engineering write-up
The customer reported that the SAM (Signal Acquisition Module) on a Mercedes W211 E320 CDI had stopped responding — power windows and interior lighting were completely inoperative. Another workshop had quoted a full replacement unit plus recoding. Before ordering a new part, we performed an inbound diagnosis. The findings confirmed the SAM was the root cause, but the stored data was intact. We opened the housing, exposed the printed circuit board, and located a defective electrolytic capacitor under the stereo microscope — it had lost capacity and was destabilizing the supply voltage to the module's logic section. We replaced the aged capacitor with a long-life type rated for higher temperature tolerance, verified the voltage supply under load, and resealed the unit. The original SAM was returned to the vehicle with all coding, VIN, and immobilizer data preserved — no recoding was necessary. Power windows and interior lighting were fully restored. The customer avoided the cost of a new module and the additional recoding labor.