no power to brown trailer wire
Brown wire is for brake light and right turn signal. There won't be power on this wire unless the brake pedal is pushed down (steady voltage) or the right turns signal is turned on (intermittent voltage/no voltage) If there should be voltage and there is none then you have loose/broken wiring or blown fuses.
press the pedal to the metal.
If wired correctly this is the brake light wire. Have someone hold the brake pedal down then probe with a voltage checker to see if the wire is broken or not. This is a small tester with a red light on it and you poke the point into the wire with the black wire grounded. Make sure all the fuses are okay and the sockets rust free, etc. Make sure the adapter (female) on the vehicle is corrosion free. I have to scrape mine out every year or so as it corrodes with oxidation.
yes, there is a way just think about it.