2010 f-150 with full towing package no TBC installed. I intalled an OEM TBC and took it to the dealer for them to flash. Everything works on it except the trailer brake. I see that it sees the TBC when I go through the setup on the dash. It charges trailer batteries and all lights work. The dealer is telling me that I must have a bad wire , it took them 1.5 hours to flash the TBC which should only take a few minutes. Any help is appreciated

 

Have you tested the trailer on another truck to make sure the brakes on the trailer actually work?

 

yes,it is a brand new trailer, tested at the RV Dealer to make sure

 

Have all of the fuses and relays been double checked to make sure they are functioning for the towing side?

You might even need a different relay or a relay because you added the TBC.