I'd use a second relay with the trigger being a switch and then run a set of cable to both the headlights and the plough lights with a diode on both cables so that the current can only flow one way and not bypass any other wiring?
This is an older thread, you may not receive a response, and could
be reviving an old thread. Please consider creating a new thread.
Mercedes-Benz Forum
BenzWorld.org forum is one of the largest Mercedes-Benz owner websites offering the most comprehensive collection of Mercedes-Benz information anywhere in the world. The site includes MB Forums, News, Galleries, Publications, Classifieds, Events and much more!