An interesting problem

First thought, swap the R2LC with a known good working locomotive, see if the problem follows the R2LC.  The fact that it's only in one section, and it takes off uncontrolled, is interesting, normally when a TMCC locomotive under power loses the signal, it stops.

Swap R2LC from a good loco to that loco.  Sometimes a poor sensitivity on a R2LC.  If you place your hand over the engine in that location does it receive signals and respond?  G

GTMA?

OK, two tips to try.  Will report back results in a day or so.  thanks

You mean GMTA?....;-)

Or something like that.

Not sure what GMTA or GTMA is, perhaps an inside joke.  Anyway, before I opened up a perfectly functional loco, like any good scientist I repeated the experiment to see if the results could be duplicated.  The loco in question ran just fine until it got to this one section of track.  My earlier observation of a "run away" was not accurate.  Uncontrolled would be the correct description.  If the loco was shut down in this location it would fail to respond when power was turned back on.  All other TMCC locos do not respond in this manner at this location, however I did place my "magic hand" over the loco as described and amazingly the loco responded as expected.  So now my question is where should the "fix" be applied?  Does the loco need an enhanced antennae or do I need to add something to the layout to enhance the signal at this location?  I will point out that the offending location is the center track of a 3 track station.  Both outer tracks do not exhibit this behavior.

That's a totally different scenario!

The first thing I'd do is look in side and make sure the antenna is properly connected.  If it's just one locomotive that exhibits the behavior, it's probably easier to add antenna, for diesels you can install a long wire antenna that wraps around the top of the entire shell, that has cured the issue for me.

If that doesn't do it, the R2LC can have a weak receiver, try swapping the R2LC with another working locomotive and see if the problem follows the board.

If neither of these totally cure the issue, you may need an earth ground wire through that section to enhance the TMCC signal.  Best location is above the tracks if possible.

GMTA - Great Minds Think Alike

you do not have a track issue per say.  it is a signal issue.

try what john said.

Thank you gentlemen.  I will continue work through the suggestions and advise.  Hopefully this adventure will help others as well.

The C-420 in my opinion are a good running engines, I am referring to the 2000-2001 when they where first issued. I think everyone should have one because (again this my opinion). If your layout has a signal issue the C-420 will find it. The antenna is the culprit, it is to small. If you extend the antenna either by adding a larger antenna or extending the lead, you should not have any problems.  

Bill

GMTA = Great Minds Think Alike

Chuck

Interference is not only caused by track above or below but also parallel tracks. Do you have multiple parallel tracks at this location on your layout>

If so, it sounds like textbook "ground plane issue". A ground plane issue will not effect every loco, only the one with the weakest antenna.

Do a search on "ground plane issue" for more info.

Rick, all his other engines run fine through the section.  Just one engine acting up.  Certainly you can boost the ground plane for it, but sometimes the easier solution is a new R2LC, if it is not a antenna issue as Bill pointed out.  G

This is in a three track station?  What is the station/platform made of?  Is there any metal involved in its construction?

No work on the issues last night, date night instead.  Bill I think you are correct in your diagnosis of the antenna.  How would one go about increasing the length?  Is there a preferred material.  

The station platforms are all wood and plastic, so no worries there.

I will research the ground plane issue further since the stable of locos with legacy or TMCC will only increase over time so other issues may be teased out over time.

You just need to use a longer piece of wire for the antenna.  I think about 30 inches works well, fine gauge, insulated.  you can run it along the inner edge of the top of shell, overlap if necessary.  

I just do what Chuck says, I run it around one complete loop and then cut it at that point.  A little hot glue, and you're good to go.

If increasing the antenna doesn't work, swap the R2LC with the original antenna.  Every once in a while you get one that won't receive right regardless of antenna.  G