Troubleshooting Interior Lights Not Working On an Enclosed Trailer

Question:

I have a 2019 legend cargo trailer interior lights do not work when hook up to a 2020 gmc 1500. There is a small 12 volt battery in the front of trailer. All lights work on the outside on trailer need help thanks

asked by: Jim

Expert Reply:

It sounds like your interior lights on your 2019 Legend are powered off a secondary battery. The exterior clearance/ marker and tail lights are powered directly from your 2020 GMC Sierra 1500. The small battery on the front is generally only used for electric trailer breakaway brakes. If being used with additional lighting the battery is replaced with a larger unit. You will want to check for any additional terminals which you may need to trace from the light switch itself.

If you have an exterior porch style light that works the culprit is likely the switch or part of the wiring for the interior lights. In the event all your additional lighting is run of the small battery on the front, it should be replaced with a Bright Way Deep Cycle RV or Marine Battery # BRW34FR and Box # 329-HM300BKS. The larger capacity is needed as the small battery is only designed to provide power for a short time to the brakes and can be easily damaged if used for trailer lighting as well.

expert reply by: Bud M