Help ID this wiring issue pls

Hello tacoma world... My trailer wiring was acting up, I traced the problem to this black box in the drivers tail light, the yellow going into the box is live and coming out isn't.
I've tried talking to the toyota dealership and we cant seem to source this "relay" "converter" theirs no part # on it and they want $160 just to bring it in the shop and have a look!!
Thx in advance

 

That looks to me to be a common aftermarket adapter for a trailer hookup. They fail once in a while. I would just buy a new one--$20 to $30 as I recall.

Here is one:

http://www.etrailer.com/Custom-Fit-Vehicle-Wiring/Toyota/Tacoma/2006/118496.html?vehicleid=20066955

(link courtesy of another thread in this forum)

 

Thanks man! Bigtime!