Mercedes ML W166 Relay Module Box Under Rear Right Seat F4 A1669063901

The Mercedes ML W166 Fuse and Relay Box Rear F4 A1669063901 is an original electrical system component designed for installation in the rear right part of the vehicle. The box ensures organized housing for fuses and relays, stable connections, and efficient management of the car's electrical circuits. Thanks to its factory design dedicated to the Mercedes ML W166, it guarantees a proper fit with the wiring harness and mounting points.

Specifications and technical data

• SKU: A1669063901
• Mark: Mercedes (Genuine OE)
• Condition: Used
• OEM Part Number: A1669063901
• Substitutable numbers: A1669063901, A 166 906 39 01
• Location on the vehicle: Rear, Right
• Category: Fuses & Fuse Boxes

Purpose and Function in the Electrical System

The presented fuse and relay box is a component of the power supply and control system for electrical consumers located in the rear part of the body. Its placement on the right side allows for optimal wiring routing and reduction of voltage drops in critical circuits.

In practice, this means:

• centralization of protection for selected circuits in the rear zone of the vehicle,
• easier fault diagnosis due to the grouping of fuses and relays in a single module,
• organized routing of wires and connectors, which reduces the risk of mechanical damage.

Thanks to its design developed by the vehicle manufacturer, the box integrates with the factory electrical architecture, maintaining compliance with load parameters and safety requirements.

Construction and Mounting Fit

The box is designed as a module to be installed in the rear right part of the body, taking into account the geometry of the recess and the routing of the wiring harnesses. The appropriately shaped housing ensures stable mounting in the vehicle and protects internal components from external factors under typical operating conditions.

Key design advantages include:

• factory sockets for fuses and relays,
• compatibility with standard electrical system connectors for the Mercedes ML W166,
• layout of current paths consistent with the original vehicle schematic.

This solution facilitates installation and minimizes the need for modifications to the wiring harness, which is important for both repairs and restoring the system after damage.

Benefits of Using an Original Box

Using an original fuse and relay box in the Mercedes ML W166 ensures the consistency of the entire electrical system. Replication of the factory connection layout minimizes the risk of incorrect consumer operation, module communication errors, and problems with computer diagnostics.

Choosing this component offers, among other things:

• maintained compatibility with service documentation and electrical diagrams,
• easier circuit identification during measurements and tests,
• reduced potential problems with fitting aftermarket alternatives with different internal architectures.

For workshops and users, this means more efficient service operations and greater predictability of the system's behavior after repair.

Condition, Verification, and Service Application

This part is a used component intended for reinstallation in a vehicle where the rear right body fuse and relay box needs replacement. This type of component is particularly useful for repairs after mechanical damage, localized flooding, or overheating of fuse and relay sockets.

Before installation, it is recommended to:

• verify compatibility with the specific equipment version of the Mercedes ML W166,
• check the condition of connectors and mounting points in the vehicle,
• confirm the correct placement of fuses and relays according to the manufacturer's diagram.

This approach allows for the safe restoration of full functionality to the electrical system in the rear of the car.

Expanding the Electrical System in a Mercedes

If you are planning a comprehensive repair or modernization of the electrical system area in your Mercedes and need other components from the same group, such as additional boxes, modules, or housings with sockets, check the available parts in the Mercedes Fuses and Fuse Boxes category.

For users interested in a broader perspective on used automotive components, including their selection, installation, and cost-effectiveness, an article describing the practical aspects of using aftermarket components may be helpful – you can find it here: when used VW parts are a sensible choice.