A member reported that the brake lights on a 2008 Thor Summit appear continuously lit whenever the truck lights are turned on, while a horse trailer connected to the same seven-pin truck connector works normally. Members suggested checking the truck receptacle and trailer junction box for wiring issues or corrosion, then working back through the trailer wiring.
Several members noted that because the horse trailer works correctly, the problem is more likely in the RV trailer than the tow...
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A member reported that the brake lights on a 2008 Thor Summit appear continuously lit whenever the truck lights are turned on, while a horse trailer connected to the same seven-pin truck connector works normally. Members suggested checking the truck receptacle and trailer junction box for wiring issues or corrosion, then working back through the trailer wiring.
Several members noted that because the horse trailer works correctly, the problem is more likely in the RV trailer than the tow vehicle, although brake pedal switch, spacer, or return spring issues were also mentioned as things to verify if the truck lights behave abnormally. Others pointed to a bad ground or voltage backfeed through incandescent filaments as a common cause of strange trailer light behavior. The discussion did not reach a confirmed fix, but the main practical direction was to verify truck operation first, then focus on the RV trailer connector, junction box, grounds, and wiring.
