Help! Polar Express Legacy

Are you running it in command or conventional?

We're running it in Legacy Command Mode.

How about some more info? You say " none of your other Mth engines have this issue".

Do you have any other Lionel  legacy engines? Is the PE the only one? How do the other legacy engines run?

Does the headlight flash when it stops? Does it run OK in conventional mode on the same layout?

The PE is the only Lionel legacy loco I currently have.

The headlight does flash rapidly when it starts to have a problem.  It then returns to a solid state when it starts back up.  There doesn't seem to be any pattern on the layout where it stops and starts...what's more confusing is that it ran perfectly fine on the layout for 2 days, then all this started.

Is the command base plugged into a properly grounded 3 prong outlet?  Remove any surge protector from the Legacy Base power adapter. Plug it directly into the properly grounded 3 prong outlet. Do not use a 3 to 2 ground lift. The Legacy base needs the ground. 

The one connection on the base is going to the common or outside rail?  

Report back. 

Watch Mike from 19:50. Legacy\TMCC needsboth outside rails connected to common. If you have isolated outside rails anywhere, this explains how to connect them without losing the isolation, but maintaining a good signal.

Just before this, Mike talks about the ground plane wire between close tracks and over-under tracks that can cause interference.

You have a ground and or common issue somewhere.

If you were to connect the Legacy base common to the transformer, will it communicate to all commons in the various blocks? Perhaps connect to all of the out commons on the TIU. Extend a wire from the TIU out back to the Legacy base.

MartyE, you're a genius!  That solved it.  I plugged the legacy directly into a wall socket and it works like a charm!  Can't Thank You enough for the advice.  I knew most here were a lot smarter than I!

Cool.  Some surge protecting outlet strips cause ground issues with the Legacy Base.