Viermalvier.de, das Geländewagenportal Foren Marken talk Mercedes Fernlicht geht nicht -> Lenkstockhebel defekt

You need two relays and less than 1/2M of wire. Everything can be installed behind the fuse box, and if you get the correct relays you can click them into the G's relay panel. The important part is to find the white and yellow headlight wires that go to fuses F4-F7. Pull them out of the fuse block and attach them to the relays. The output of the relays then goes back to the fuse block.

Very easy, your lights will be brighter, and the turn signal switch will last forever!