Mercedes W211 Battery Module Trunk Relay Control Module Unit A2115408645

The Mercedes W211 Trunk Battery Control Module is a specialized component from the Electronic Control Modules and Controllers group, responsible for precise power management in the rear of the vehicle. Located in the trunk area, this module works with the electrical system, stabilizing the operation of systems powered by the rear zone and supporting the reliability of onboard electronics.

Specifications and technical data

• SKU: A2115408645
• Mark: Mercedes (Genuine OE)
• Condition: Used
• OEM Part Number: A2115408645
• Substitutable numbers: A2115408645, A 211 540 86 45, 0199000012, 0 199 000 012
• Location on the vehicle: Rear
• Category: ECUs & Computer Modules

Purpose and Function in the Vehicle

The offered module is dedicated to Mercedes E-Class W211 models, where it acts as a control element within the rear body section. As a component mounted in the rear zone of the vehicle, it works with the battery system located in the trunk, monitoring energy flow and the operation of associated relays. This ensures a stable power supply and controlled distribution of electrical loads.

This design solution allows for relieving the main harnesses in the engine bay and improves the organization of electronics in the vehicle. The module is part of Mercedes' factory electrical architecture, which promotes system consistency and minimizes the risk of compatibility issues.

Benefits of Using an Original Rear Module

Using an original control module in the rear of the vehicle translates into a number of practical benefits:

• maintaining the factory logic for controlling the power system in the trunk,
• proper cooperation with other controllers in the vehicle network,
• consistency of electrical parameters with the Mercedes W211 installation,
• reducing the risk of communication errors in the vehicle bus.

For users and workshops, this means easier diagnostics, predictable behavior of electrical systems, and greater certainty that replacing the component will not disrupt the operation of other controllers.

Installation and Operational Characteristics

The module is designed for installation in the rear of the vehicle, in close proximity to the trunk battery system. This placement shortens the length of power cables, improves connection quality, and facilitates service access. In most cases, replacing the component involves disconnecting connectors, removing the mounting, and installing the functional module in the same location.

As a used component, the module comes from disassembly and is intended for users and services looking for an economical yet technically matched solution. Choosing such a component allows for reduced repair costs while maintaining compatibility with the vehicle's factory electrical architecture.

Practical Application in Servicing

The trunk battery control module is primarily used for:

• resolving faults related to power supply in the rear of the vehicle,
• repairs after flooding or mechanical damage in the trunk area,
• restoring the functionality of electrical systems after incorrect installation modifications.

Due to its role in the power supply system, it is an essential component for the stable operation of many electrical consumers located at the rear of the car. A properly selected and functional module helps to reduce errors in diagnostic systems and undesirable voltage drops.

If you are planning a comprehensive repair or upgrade of the rear electronics area in your Mercedes and need other parts from the same group, such as controllers, power management modules, or relay units, check the available parts in the Mercedes Electronic Control Modules and Controllers category.

Selecting a Used Module and Technical Knowledge

When choosing a used control module, it is crucial to pay attention to compatibility with the specific vehicle version and installation parameters. In workshop practice, aspects such as matching the electrical architecture, correct identification by part numbers, and proper installation and potential adaptation procedures are important.

To better understand how to safely use used automotive electronics, how to select modules by manufacturer markings, and what to look for during installation and diagnostics, it is worth consulting the guide: Used Automotive Electronics Onboard – Why Choose Used ECU Modules and Sensors?