cmpcpro

Ok I tried searching with no luck. To remove the TCU on the W220 you need to remove the connector on the top of the TCU closest to the windshield. Using a small flat head screw driver to push the tab in while getting your finger around the edge of the connector end closest to the windshield. After that is off and out of the way you can pull that end of the TCU up and out of the box and rotate it so the connector remaining on is facing upside down. At that point it's easy to remove that connector and then installation is the reverse, but make sure you connect the last connector (closest to front of car) first before dropping the TCU down into the box. Then the second connector can easily be rotated back on.