CORRECTING MY POST THAT ORIGINALLY REFERRED TO A LIONEL LOCOMOTIVE!
Corrected post: I have a K-Line K2402-2001 Alaska GP38-2 with LTI/TMCC. Has been in its box forever (at least since being purchased years ago), but I decided to add it to my fairly decent roster of Alaska RR locomotives (Lionel, MTH, and K-Line).
I am controlling all the TMCC and Legacy locomotives with Lionel's CAB-1L and base. All are performing well, except for the aforementioned GP-30, which is running well enough and with all basic functions working, except that it tends to lose its sounds when crossing through many of my switches (all are Ross). It's almost as if the locomotive must be fitted with a battery to "carry" the sound system through such momentary breaks, but since I do not have the engine's operator's manual I can't determine if there really is a battery and, if so, where it is located in the engine and how to get to it. Tried doing a Google search for the manual, but with no luck.
Perhaps someone here has had similar experiences with the same or similar locomotives and can provide some info.