w205 Benz FBS4 802/902 Key Adapter Installation Instructions

Installation Instructions

Step 1: Connect the Main Control Unit

Locate the original vehicle start control module as shown in the video below. Connect the adapter harness to the original connectors, then plug it into the main control unit to power it on.

Important: Make sure the blue connector on the main control unit is fully inserted and securely connected.

Step 2: Remote Learning & Antenna Installation

Program the remote control to the main control unit.

Place the high-frequency antenna inside the rear ventilation grille or inside the passenger-side A-pillar.

Then test the vehicle's remote control functions to ensure everything works properly.

Step 3: Install the Original Key

Remove the dummy battery from the main control box and install it into the original remote key.

Place a thick piece of tissue paper inside the main control box as padding.

Position the original remote key inside the box exactly as shown in the picture below.

Remove the emergency mechanical key blade, place it inside the main control box, and securely close the cover.