Someone contacted me asking how to wire DRL’s (Daylight Running Lights) on his caravan. He wanted to attach a strip of super bright white LED’s on each front edge of the caravan so as to make the edges more visible during the day. However, he wanted the LED’s to come on only when the engine was running and turn off when the sidelights of the vehicle were turned on (as is normal for DRL’s on a vehicle) and the other requirement was not to have to make any wiring changes to his tow vehicle.
There was only one way I could think of wiring the LED’s to fit his request. If you are considering doing the same, this is the solution I came up with:-
The LED’s are powered via a suitable fuse from the fridge circuit. This ensures they will only turn on when the engine is running. A relay is used to interrupt this circuit and is activated by the side lights being turned on (Pin 7). I have shown a fuse in this circuit as well. The relay can be any suitable 12 volt automotive relay.
The fuses and fuse holders can be found in most auto-parts stores.
I’m not sure if DRL’s are strictly legal or not on a caravan, but I do like the idea of a LED strip highlighting edge of the caravan when you are towing. Anything to increase visibility has to be good!
I hope this circuit gives you a few ideas.
Here’s the PDF file of the drawing above: Daylight Running Lights on a caravan