Based on your description of what has occurred I believe that there is a short somewhere that is causing the problems. But the converter box alone from # 119250KIT cannot be replaced by itself because it is not offered. It would require a whole new complete harness. view full answer...
In the instructions for the ZCI Circuit Protected Vehicle Wiring Harness w/ 4-Pole Flat Trailer Connector and Installation Kit # 119250KIT under the INPUT SENSOR - DETERMINATION heading there is an asterisk after the BTT configuration explanation. If you look at the bottom of that box the asterisk says that you may need to route the tail wire to the rear license plate illumination circuit and/or brake to center high stop light (see attached picture).
I recommend taking this step as it... view full answer...
First thing you should do at this point is test the 4-way of the wiring harness with a circuit tester part # PTW2993 for voltage on all of the right pins when the taillight signals are being applied. Just like in the video I attached.
If the voltage checks out there but the trailer lights still don't function right then the problem is on the trailer wiring. That would mean that problem is either due to a ground issue or a short issue.
Make sure that the trailer side connector are clean... view full answer...