Troubleshooting Trailer Wiring Where Running Lights Come On Disconnected in Storage

Question:

my trailer has been parked for a month with trickle charger.cargo with two 12 v bat last night the neighbor said my running lights were on and I saw them on this AM. they are still on. no vehicle attached, plug hanging sown out of the weather, shore power plugged in for the charger and internal lights. Why are they on??? Thank you

asked by: Steve H

Expert Reply:

You must have a short between the running light circuit of the trailer and the 12 volt battery charge line which is causing the running lights to illuminate. First place to check is the trailer connector that connects to the tow vehicle. Corrosion on the pins or the wiring behind the connector can cause a short. Since it developed over time that's what I believe is going on. I attached a couple help articles on trailer wiring for you to check out as well.

expert reply by: Jameson C