@illinoiscentral posted:You might have a two-problems problem.
The first might be bad connections between sections of track, and the second might be TMCC signal integrity.
Edit: I am only addressing the first problem below!
Having a caboose with an old school incandescent light bulb can help; it draws a bit of current, and it doesn't move when power is on. Roll the caboose around the loop and look for it dimming, and maybe check the track voltage near the caboose. If there is a bad joint, you should see a reduction in voltage.
Another trick I have learned, mostly from slot cars, is take apart the track at the point farthest away from where power is attached, and make sure the track has power on the very ends. Why? Say you have one bad connection. The conductors (things that carry electrical current) coming from the other side of the bad joint is masking the problem. Artificially creating another open circuit exposes that bad joint. Also do the caboose voltage drop trick.
Keep in mind that everything besides superconductors have resistance, so you should get a slight voltage drop down each piece of track, across each joint (with electric current flowing thru it, that's your lighted caboose).
Hmmm, we should have a "resistor cars", big ol power resistor on a rail car, drawing maybe 5A at 18V, then maybe some cheapo made-in-China digital AC voltmeter reading what the voltage is.
Pretty close .......
