Justintyme
Active Member
Well, 40 years ago ( and yes, I remember them too.) And up to recent times, 2010 in my case, it was simple enough to wire a trailer, using a relay.1 function, one wire. No problem. But now in my 2014 w212 Eclass, the brake and park lights are fed by a single cable. And try as I might, my so called Smart Relay, is unable to differentiate between the two, and send the voltage to the correct brake or park bulb..technologyIt’s over 40 years since I did this but iirc it should be black to left taillight and brown to right taillight.
Functionally no different but it could get confusing if you have a problem and are trying to diagnose a problem