As per my notes from the Lionel service class, Placing a .01uf capacitor from the grounded outside rail across to the non grounded insulated rail will give you back full TMCC signal through the area where the insulated outside rail is located. This is what was explained by Mike Reagan during the class. As I stated above I have never done this personally. This is done to boast the signal where one outside rail is insulated as is the case with the non-derailing feature of the switches.
This will do nothing to help the RS11 since it will not run in TMCC mode at all. If the RS11 will run conventionally but not in TMCC the first thing I would do is test the R2LC Radio board to determine if it is working. I do this on a test board that was purchased during the class. If the board test ok then next you need to test for continuity from the antenna back to the R2LC and to make sure the antenna is not grounded to the frame of the loco.
Not having the test equipment your other option would be to swap out the R2LC with one from a working engine to see if it fixes the problem. If the swap does not fix it then you need to determine why the antenna is not picking up the TMCC signal. Do not try this unless you are comfortable doing so. The R2LC connects to a 24 pin header. Not getting these pins lined up properly will destroy the board. Also check to make sure there is no continuity between the antenna and ground. Set your meter to ohms or continuity and put one lead on the antenna and the other to somewhere on the engine frame. It would be best if you checked the antenna before swapping any boards.
Railsounds 3 and later TMCC Engines have 3 boards in the engine that to a novice all look similar. The R2LC board, the railsounds audio board and the railsounds audio power board. They are all on 24 pin headers and are not interchangable within the engine as in; do not put the board on the wrong pin set.
Swapping the R2LC in the SD40T-2 might correct it over the affected area if the board frequency on the R2LC in the engine is off slightly. . .
