Can't seem to find problem

What exactly happened? Did the bad half of the layout power up?

Did you try to switch the outputs at the TIU?

You can test by hooking it up to a test track or spare piece, but you might be covering that with how you swap them now.

 When you connect the good half of the layout to the other channel that went to the bad, does it work??

 I just had  a similar problem at the grandkids house. Turns out, it was right at where the track lock-on powers the track. I had to move it to another track section. I'm going to add more lock-ons to spread out the draw of all the lighted cars they got for their birthdays!!

i switched handles and its always the handle that is powering the north side of the layout that wont power up.  i hooked up a test track and put a caboose on their and it worked.  let me go test some more

Vitto,

Almost certainly this is not a DCS problem.

Most likely you have a wire disconnected somewhere between the TIU output and the layout's tracks.

That is good! You are narrowing down on the problem. It sounds like what Barry has said is true. There is probably somewhere that the wire is not getting power to the track in that area, not a tiu problem then.

 That's why I described the issue of the lock-on. When some power is drawn thru one connection, it can fail and that shuts down everything it's connected to.

looking at my prior post, i need to learn how to type.  i wanted to say that i did blow a fuse between the z-4000 and the tiu.  i have done this.  when powering up the voltage, my magic lights are one bright, and one really dim.  of course, the dim one is on the part of the layout that wont power up.  i disconnected the wire going from the magic light to the star wiring board (not sure what is called) and the both light go very bright.  i believe that this tells me that the problem is after the magic light.  i am going to disconnect every star wire and reconnect one at a time and see what happens.  is this a good idea?

Well... It sounds like there's a short of some kind. So yes, that's how you can narrow down where to find it. As long as nothing gets hurt while you're searching. The fuses are there just for this condition. So either keep searching and have spare fuses handy, or use a meter to find which wire has a short.

 I hope I'm understanding you correctly!!

When the light is dim, the fuse holds?? After you narrow down the area, it will be interesting to see if it's a piece of equipment on the rails, or something else.

Vitto,

If you're blowing fuses on whichever TIU channel is connected to the problem half of the layout, Joe is correct. You almost certainly have a short in the layout wiring or tracks.

Vitto,

   Start checking all the wires in and around your transformers, Breakers & TIU, especially your 24 port transfer blocks, if you use them.  Then follow each line track side to assure proper connection and that nothing has been crushed or damaged somehow.  You either have a bad track or your wiring has been damaged in some way, causing a major short to occur, or you have something laying across your tracks that you do not see.

PCRR/Dave 

Also check for debris on the tracks, shorting the center rail.  Is there a 5-volt PS2 loco on that side of the layout?  If so, remove it and see what happens.

I'd remove everything once you find the power block where the short is. Then add them back, one at a time. I've seen cars have shorts in the wheel sets, melted wires inside, etc. It can be anything!

 A few of my MTH diesels like to pull out the track nails with their new speakers with strong magnets!!