Train lover:
Something unexpected happened to me with a Sunset 3rd Rails steam engine I bought used. It had an ERR upgrade already and when I changed the engine's address (the #), the backup light on the tender stopped working. I gave up looking for that problem and continued reprogramming that engine which you always should do after resetting the address on these engines, as there's a setting for the motor: large or small. This is a pretty big northern type and when I set the motor size to large.....guess what? the tender light worked again. I don't know for sure because I didn't repeat that sequence just to verify. But, it's with looking at if you have recently reset your engine's address.
Phil
