Does it blink in a particular pattern? Certain patterns of cab blinks can indicate certain problems with the engine. Have a service snack with Dean, Lionel's director of customer service, to find out what these may mean.
Now, if your cab light is green, then I'm not quite sure what that may mean. Perhaps Gunrunner John, Dave Olson, or someone else would know better. It would also help to know which version of the Legacy Big Boy you have, as there are multiple versions.
