Diagnosing trailer light issues

I find the most common issue is a wire grounding against the frame of the trailer. I provided a short general overview of where to get started.
1. Remove bulbs and unplug trailer.
2. Circuits should be open and your multimeter should NOT have continuity between any 2 pins.
3. Find which pins have continuity and trace the wires back.
4. If no pins have continuity make certain your ground pin has continuity to the trailer frame. You will then systematically check for continuity between each pin wiggling/jostling wires listening for a beep.
Hope this helps!

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Open circuit
Closed circuit
Shorted circuit
LED sealed beam lamps with individual ground wires to each lamp are the only way to go with ! Place alligator clips on a 12 volt buzzer and connect to the shorted circuit , this will sound the buzzer . Wiggle and Shake the harnesses , when the buzzer stops you have found the area of the short circuit . 5/30/23