Troubleshooting Trailer Lights That Don't Work With Power Flowing to It
Updated 04/09/2025 | Published 04/05/2025
Question:
I plugged in the trailer lights to my caravan trailer and they don’t work. A friend came over and tested the power on each wire and it looks like there’s power coming through. The first lights are the running lights on the side of the trailer tongue and there’s power getting through to that light, but they don’t light up. What could be the possible cause? If the running lights don’t work even though there’s power going in there would the other lights not work also? I’m going to replace the running lights and see what happens. Any ideas?
asked by: Ray S
Expert Reply:
Hey Ray, this sort of thing happens quite a bit actually. Usually what's happened is that there is either a short in the circuit, or there's an issue with the ground.
I'd recommend checking the grounds and make sure they are connected securely, and attached to a clean bare metal surface. You'll also want to make sure there is no dirt, corrosion or debris on the connectors as that could also be causing your issue.
Next, If the grounds and connectors look good, I'd check the wiring and inspect it for any damages. Look for any nicks, breaks, or any obvious breaks.
The last thing you could do if you haven't already is check the fuses and make sure they are not blown.
If you're still having issues, let me know in the comments, and we can keep attacking this thing.
Product Page this Question was Asked From
Pollak Metal 7-Pole, RV-Style Trailer Socket - Vehicle End
- Custom Fit Vehicle Wiring
- Trailer Hitch Wiring
- Vehicle End Connector
- 7 Blade
- Plug Only
- Pollak
more information >
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Ray S.
4/9/2025
Thanks Bryce. It ended up being a ground wire. The ground wire apparently being so old was not working properly so my friend came over and drilled a hole in the trailer and hooked up a new ground wire and the lights work fine. Thanks again for responding and your suggestions.