Check the location beneath the rear storage area panel for the compact assembly that manages all auxiliary circuits. Each connector is numbered, allowing precise identification of each protective link and relay controlling lighting, sensors, and power outlets. Labeling on the unit corresponds with the vehicle’s service manual, which simplifies troubleshooting blown links or intermittent failures.
Before attempting any replacements, disconnect the battery negative terminal to prevent accidental shorts. Use a multimeter to test continuity across each protective element; this helps determine which section is compromised without removing the entire unit. Keep a small set of spares compatible with the amperage ratings specified for each circuit.
Some sections are dedicated to high-current devices such as the rear defogger or audio amplifier. Identify these by their thicker contacts and reinforced housing. Document the layout by photographing the arrangement before removing any components to maintain correct reinstallation.
For rapid diagnosis, note the color coding of each conductor; the manufacturer assigns specific hues to power, ground, and control lines. This reduces the risk of installing an element in the wrong slot and causing further electrical issues. Proper alignment ensures stable operation of auxiliary lighting, sensors, and electronic modules integrated in the rear compartment.
W204 Trunk Fuse Box Diagram
Locate the power distribution panel behind the rear access panel on the cargo area’s left side. Identify the 7.5A slot marked for tail lighting and the 20A position controlling the rear wiper motor. Each slot is engraved with amperage values and corresponding circuits, allowing precise identification without referencing external manuals. For replacement, always use the same rated cartridge to prevent short circuits or intermittent failures.
Map the secondary relay layout adjacent to the primary panel to track auxiliary circuits such as the rear power outlet and luggage compartment illumination. Pay attention to the 15A and 25A terminals, which handle defogger and central locking modules. Maintaining a clear photograph of the layout before removal simplifies reconnection and prevents misalignment of critical circuits during maintenance or diagnostics.
Locating the Trunk Fuse Box on W204 Models
Access the rear electrical panel by opening the storage compartment behind the rear seats. On sedans, remove the side trim on the right-hand panel; in estates, check beneath the floor lining near the tailgate. Use gentle leverage with a plastic trim tool to avoid scratching the interior surfaces.
Inside, the power distribution center is mounted vertically against the interior wall. Look for a black rectangular unit with multiple colored connectors plugged in. Labels on the cover indicate circuit allocations such as lighting, auxiliary power, and audio components. Keep a flashlight handy to identify tiny markings.
Follow this sequence to ensure accurate inspection:
- Release two retaining clips on the side cover.
- Pull the cover outward to expose the terminal block.
- Check the slots for corrosion or loose connections before attempting replacements.
- Always document the arrangement of connectors to prevent misalignment during reassembly.