Troubleshooting Trailer Interior Lights That Won't Work While Exterior Lights Do Work
Question:
2015 f350 dually. All interior lights wont work in trailer. Exterior lights work fine on trailer. Suggestions?
asked by: Helen G
Expert Reply:
The exterior lights on your trailer - stop, turn and tail - and the interior lights will usually be fed by different power sources. On an RV-style 7-way the stop/turn light signals are carried on the pins at the 3-o-clock and 9-o-clock positions and the tail/clearance light signals are carried on the pin at the 11-o-clock position.
The +12V auxiliary power circuit on the 7-way that would normally feed a trickle charge to maintain a battery mounted on the trailer is carried on the pin at the 1-o-clock position. Please refer to the linked photo that shows each circuit on a typical 7-way socket.
The issue with your trailer's interior lights depends on how they are wired. Is there a battery on the trailer that powers the interior lights? Or does the trailer have no battery and instead pull its power for interior lights from the 7-way circuit that is fed by the vehicle battery?
I suggest you find the point where all of the interior lights' wiring joins the trailer's, either at a trailer-mounted battery or to the 7-way's +12V auxiliary circuit. Your trailer could also have a fuse/power distribution box that might have a blown fuse for the interior lights.
You could also simply have a case of corrosion on/in the connectors that is preventing the +12V auxiliary power from reaching the trailer.
Product Page this Question was Asked From
Ford Replacement OEM Tow Package Wiring Harness, 7-Way
- Custom Fit Vehicle Wiring
- Trailer Hitch Wiring
- No Converter
- Custom Fit
- 7 Round - Blade
- Tekonsha
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