Mercedes S212 Fuse Box Rear Relay Control Unit Electric Module SAM A2129001506

Mercedes S212 Fuse Box Rear Relay Control Unit Electric Module SAM is an advanced SAM electrical control module responsible for power distribution and the control of selected circuits in the rear of the vehicle. Thanks to its factory design intended for Mercedes models, this component ensures stable operation of the electrical system and proper cooperation with comfort and safety systems. This solution is dedicated to users who expect reliable fitment with the original wiring harness and predictable behavior of electronic systems.

Specifications and technical data

• SKU: A2129001506
• Mark: Mercedes (Genuine OE)
• Condition: Used
• OEM Part Number: A2129001506
• Substitutable numbers: A2129001506, A 212 900 15 06, 5DK011023
• Location on the vehicle: Rear
• Category: Fuses & Fuse Boxes

Purpose and function in the vehicle

The described SAM module acts as the rear fuse and relay box in the S212 body style, integrating several key power and control functions into a single housing. Located in the rear of the car, it handles selected electrical circuits, which allows for organized wiring routing and reduced cable length. Such a solution promotes lower voltage drops and more predictable operation of electrical consumers.

Thanks to the design developed by the vehicle manufacturer, the module works with the Mercedes electrical architecture, maintaining compliance with factory safety and diagnostic standards. This is particularly important in the case of modern systems, where the fuse box is no longer just a passive distributor, but a component actively participating in power management.

Construction and technical characteristics

The rear fuse box module in the S212 has been designed as a compact, multi-layer block integrated with control electronics. In one housing, it combines:

• a fuse section responsible for protecting individual circuits,
• a relay section performing the switching of selected functions,
• an electronic part responsible for control logic and communication with the rest of the installation.

Such integration allows for a reduction in the number of connections and connectors, which translates into greater system reliability and easier diagnostics in the event of faults. The module is prepared for installation in a dedicated location in the rear of the body, which facilitates service and access to the fuses.

Service application and benefits of replacement

Replacing the rear fuse box module is recommended in situations where there are problems with the power supply of selected circuits, unstable operation of consumers, or signs of overheating around the fuse and relay sockets. Using the original SAM module intended for the S212 allows you to:

• restore proper power distribution in the rear of the vehicle,
• maintain compatibility with the factory installation and software,
• reduce the risk of communication errors in the vehicle's electrical network.

The item from the Fuses and fuse boxes category is crucial for protecting the installation against overloads and short circuits, which is why its technical condition has a direct impact on the reliability of daily operation.

Condition, fitment, and installation

The offered module is a used part, which in practice means the possibility of obtaining a factory component at a more favorable price than a new replacement. When properly matched to a specific vehicle version, it ensures plug-and-play with the factory wiring harness, without the need for mechanical modifications to the housing. Before installation, it is recommended to perform a standard inspection of the connectors and the correctness of seating in the dedicated bracket in the rear of the body.

Due to its role in the electrical system, installation should be performed in accordance with safety procedures – disconnecting the power supply, checking the condition of the wiring harnesses, and verifying the correct seating of fuses and relays after installing the module.

System expansion and related components

If you are planning a comprehensive repair or upgrade of the electrical installation area in the rear of your Mercedes and need other components from the same group, such as additional protection modules, box housings, or service connectors, check the available parts in the Mercedes Fuses and fuse boxes category.

For users interested in broader modernization of electrical systems and lighting, including the selection of LED or Xenon headlights and related controllers, a guide describing the practical aspects of selecting used components may be helpful – you can find it in the article Seeing more and better – a complete guide to selecting and replacing used LED and Xenon headlights.