Mercedes W164 W251 Front Seat Wiring Loom Harness Left N/S A1645400074

Mercedes W164 W251 Front Seat Wiring Loom Harness Left N/S is an original electrical installation component designed for the driver's seat in Mercedes vehicles with diesel engines. It enables a safe and stable connection between all seat components and sensors and the vehicle's main wiring harness, ensuring the proper operation of comfort and safety functions. Thanks to its factory design, the harness is precisely matched to the geometry of the seat and floor, which facilitates installation and minimizes the risk of wire damage.

Specifications and technical data

• SKU: A1645400074
• Mark: Mercedes (Genuine OE)
• Condition: Used
• OEM Part Number: A1645400074
• Substitutable numbers: A1645400074, A 164 540 00 74
• Location on the vehicle: Front, Left
• Fuel type: Diesel
• Part type: Wire Harness
• Category: Wiring Harnesses, Cables & Connectors

Purpose and function in the vehicle

The presented wiring harness is a component of the front left seat installation, operating in the front area of the vehicle. It is responsible for transmitting signals and power between the seats and the main electrical system, which is crucial for the operation of functions such as electric adjustments, heating, occupancy sensors, or passive safety systems, if present in the specific car configuration. Using a dedicated harness allows for maintaining electrical system consistency and reduces the risk of module communication errors.

Design and fitment for Mercedes W164 / W251

The harness has been designed specifically for the Mercedes W164 and W251 platform, taking into account the seat mounting layout, cable routing under the carpet, and connector placement. Properly selected segment lengths, branches, and mounting points allow for:

• routing wires in factory channels and clips,
• limiting stress during seat movement and adjustment,
• reducing the risk of abrasion and insulation damage during operation.

Such fitment translates into stable operation of the seat installation and facilitates service, as access to connectors and branch points is consistent with the manufacturer's factory documentation.

Compatibility with diesel engine vehicles

The harness is intended for diesel engine versions, which is important for compatibility with the electrical configuration of a specific vehicle variant. In cars with diesel units, there are often differences in module placement and the routing of main harnesses, which is why using the correct component allows avoiding issues with wire length, connector types, or pin assignments. As a result, the installation process is orderly, and the system maintains parameters consistent with the factory design.

Characteristics of the used component

The offered harness comes from dismantling, which means it is a used component that retains the functionality required for further operation. In practice, this allows for an economical repair of the seat installation in the event of damage to wires, connectors, or insulation in the previously installed part. Choosing an original, used harness from the same model series is often a beneficial solution compared to adapting universal wires, as it ensures compliance with the factory manufacturing standard and minimizes the need for modifications.

Support for seat installation upgrades

Replacing the seat harness can also be part of an equipment upgrade, for example, when retrofitting the car with additional seat functions within the same model platform. Thanks to the factory layout of connectors and branches, it is easier to maintain the correct installation topology and avoid assembly errors. If you are planning a comprehensive repair or upgrade of the front seat area in your Mercedes and need other components from the same group, such as wire sections, connectors, or additional under-seat harnesses, check the available parts in the Mercedes wires, harnesses and connectors category.

For users of diesel vehicles who are simultaneously servicing the fuel system, a guide describing diagnostics and selecting components by catalog numbers may be helpful – detailed information can be found in the article Fuel system – injectors, pumps and fuel tank: maintenance and regeneration.