Mercedes-Benz W211 Trunk Battery Control Module - Used Original Parts

Diagnosis and Common Symptoms

From the workshop floor, the W211's Battery Control Module (BCM) is a frequent culprit for a host of perplexing electrical issues. A failing module will disrupt the vehicle's sophisticated dual-battery power management, leading to distinct and often frustrating symptoms. The most common indicators we diagnose are the red "Battery/Alternator - Visit Workshop!" warning in the instrument cluster, even with a new battery and a tested alternator.

Drivers will also experience a "Convenience Functions Temporarily Unavailable" message, as the BCM fails to correctly manage the auxiliary battery circuit. A critical symptom is a severe parasitic drain that can deplete a fully charged main battery overnight. On a diagnostic level, a faulty BCM will typically log fault codes such as 9051 (Component N82 BCM is defective), 9091, or trigger CAN bus communication errors with related control units.

Introduction

Restore the critical power management system of your E-Class with a reliable, workshop-tested component. This is a Genuine Mercedes-Benz Trunk Battery Control Module, carefully removed from a donor vehicle. Each unit is rigorously bench-tested to verify correct voltage regulation, CAN bus signal integrity, and response to load, ensuring it performs precisely as the factory intended. Avoid the uncertainty of aftermarket parts and choose a proven, cost-effective solution.

Product Details

• Brand: Mercedes-Benz
• Model Compatibility: Mercedes-Benz E-Class (W211 Chassis | 2003-2009) - E320, E350, E500, E550, E55 AMG, E63 AMG
• Part Name: Trunk Battery Control Module (BCM) / Batteriesteuergerät
• Condition: Genuine Used (Tested Working)
• Notes: Located in the trunk spare tire well, adjacent to the main battery. It is essential to match the part number from your original module to ensure full compatibility with your vehicle's specific configuration.