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Trailer LED Tail/Clearance Lights Illuminate at a Low Level Even When Tow Vehicle is Not Running


I replaced all of the incandescent exterior lights on my small travel trailer with LEDs. Everything works as it should . . . lights, brake lights, turn signals. However, as long as the trailer is connected to the towing vehicle, all the LEDs have a faint glow, even when the towing vehicle is parked and not running. The towing vehicle is a 2013 Hyundai Santa Fe GLX. I know that LEDs dont draw much current, but I dont feel comfortable leaving the umbilical plugged in during anything longer than a fuel stop.


Helpful Expert Reply:

It is not unusual for extremely-efficient LED trailer lights to show residual low-level illumination when installed in lighting circuits that originally had incandescent lights. These circuits typically always carry some small amount of power even when the tow vehicle is off. With low-efficiency incandescent type lighting this low power will not be evident as it is not enough to cause those bulbs to light up, but with super-efficient LED lights it can be enough to make them illuminate.

The current draw from a trailer's entire lighting system will be roughly 10-times higher for equivalent incandescent bulbs than for LED bulbs. Even at full illumination LEDs draw a very small amount of power, so at only partial illumination their current draw will be tiny. It is not likely that this low-level illumination will cause battery drain unless left connected (with the vehicle not running at all) for a long period of time, say many days or even weeks. This can vary a bit based on the battery capacity and its age and condition.

As you note, one option is to unplug the trailer connector for periods when the tow vehicle will not be operating to prevent the potential for battery drain.

Another option is to use adapter # C57003. This 7-way plug and socket adapter plugs in to your vehicle 7-way and provides a new 7-way socket for your trailer. The adapter includes load resistors that should prevent the low-level illumination by mimicking the higher resistance of incandescent bulbs.

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