Lionel Hampton,
Can you identify the engines you have in your lash up (Please include product #, what it is (RS11, SD70ACe etc), TMCC or Legacy and if you could include a video of the lash up Causing the short light to come on. If you are running a early model engine it may start long hood forward instead of short hood forward as modern diesels are set up. That could cause the issue of the engines pulling against each other. If they are on a curve the wheels of an engine could be lifted off the tracks causing the short.
Thanks
JohnB