Newbie question: My motorcycle trailer has one light not working. How do I detect where there is a break in the wiring, if that's the problem? I'll also check the bulb but I suspect it's a wiring issue.
In this case a 12vtest light with a pointy end is your best friend!! I'd first test the light socket in question and if you don't have any voltage, check the bike plug and if you've got voltage there, check all the wire connections. Also to ensure a good ground I'd run about an 8' piece of 12ga wire connected to the negative batteryterminal to the test light so's you can make sure you've got a good ground for your test light...
Try the test light, but usually for these types of problems you don't even need any test equipment. The problem canoften be spotted visually.
The most likely culprit, other than a burned out bulb, is the lamp socket/assembly. I can't believe how cheaply these are made. In the "old days" they actually soldered the wires coming into the lamp assembly but now they are just a press fit, with a sharp pin that penetrates the wire insulation.
We may be neighbours, so if you can't fix it, let me know. I'm in the electrical business.
If you have any of the blue colored "tap & run" wire connectors, that is a really good place to look for problems. Also look for any place that the wires may have been pinched or bent back & forth....wires don't like to be attached to a hinge.