Z-4000 Trouble Shooting

Wow. no kidding on the access. 

Shorts are not bypassed they are eliminated by fixing the problem.

Regarding the crossovers. It should be fine, but you should check to see if there is any connectivity between the center rails of the A & B loops. Plus while you are at it make sure there is no connection between any/all outer rails and and center rail.  Remove any transformer connection when you do this check or any jumpers between sections. There should be zero connectivity.

You have a whole lot of track going on. Looks like an opportunity to cross wire something and create a short.

Nice paint job on the background. And very creative on the vignettes, nice modeling too.

I have access to the underside of my layout so it is easy to use either buss of star wiring. I kind of think due to the access challenge, I would try to run star wiring to a point I could access. This would enable me to take any track section out of the picture, to "easily" figure out where the problem section(s) are.

BTW Atlas makes insulated rail jointers if you want to avoid cutting track. I've redone my layout so many times I avoid cutting track as much as possible. Or you could use an air gap.

Thanks and all your recommendations make good sense.  I'm dreading having to climb into the room to sit and rewire that outer loop but I see no other way to remedy the problem.  I probably won't tackle this until later in the week.  I'll keep you posted.

Problem Solved!  Thank you all for your assistance and great advice, running the bus line and eliminating all the prior wiring appears to have solved the short issue.