Walthers Dome Passenger car short

[Gene P.]

Hello! The above car is shorting out my layout. I will be opening it up later, any thoughts as to what I should look for?

[GlennW]

I'd start with the trucks & axles to be sure they are mounted correctly. You may have one or more wheelset installed backwards. If this is true, I've seen some guys mark the insides of the wheels with a green/red dot.

[Gene P.]

Turns out it is a Bachmann lighted dome car. I removed the shell, tested it on a test track with the shell off and it worked. Replaced the shell, put it back on the layout and it runs, with no problem. I think the problem was in the trucks and by my moving them around I corrected it. Seems too easy, but it works.

[SteamGene]

Swapped trucks are a frequent cause of shorts.  I normally take some white paint and paint a line on the bottom of the car or tender and along the axles of the wheels before I remove a truck.  Then I'm sure I'm replacing the trucks correctly, yet don't have to squint to see where the insulators are.  When I have pick-up wheels, I never remove them all from the truck at the same time. 
Gene

[Elnovato]

I though it would not matter. I have a Bachmann cargo car that had a similar problem. I took off all the axles and put them back on (randomly) and the problem was solved. I guess by chance I put them back the "right' way...