DCS E-stop

Perhaps you are tripping the breaker in the transformer due to running too many engines, lighted passenger cars, etc. 

ARe you feeding power for the TIU thru AUX or FIXED 1?

Please describe how the transformer & tiu are connected to the layout.

Do you hear a click from the zw when the trains stop?  If the breaker opens, all would shut down.  Red light could be burned out.

 the hot passes through a fuse block and then connects to center rail.

Although it's not the cause of your problem, the fuse is in the wrong place. It should be in the Hot wire between the transformer and the TIU channel input.

 This and a whole lot more is all in MTH’s “The DCS O Gauge Companion 2nd Edition", available for purchase as an eBook or a printed book at MTH's web store!

Yes, I'm absolutely certain.

The fuse is in the wrong place in all of the diagrams. It's protecting the engines but not the TIU. In order to protect both the engines and the TIU, it needs to be in the Hot wire between the transformer and the TIU.

MVD,

   Heed what Barry is teaching you, put your Scott 10 Amp resettable breakers

between your ZW and your TIU channel, and between your KW & your TIU channel, on the red center rail wire.  The Breakers are to protect your TIU and your P2 engines.  The old ZW's & KW's have old time slow blowing breakers in them.  No need for an extra TVS, the TIU has TVS built into the unit, and it works just fine.

If you set your layout up in blocks, as Barry explains in his Book, you should have no problem with breakers popping all the time.  You have been darn lucky so far that you did not damage your TIU or at least blow an internal TIU fuse. 

PCRR/Dave

MVD,

   I have been using the TVS in the TIU as my safe guard for many years , have never had a problem, I see no need for an additional TVS.   However I am the guy who just put the Scoot type breaker on my Legacy base. 

PCRR/Dave

So if I move the fuse block in between the transformer do I still need my tvs on the output side of the tiu or can I get rid of this all together?

Having redundant TVS protection won't hurt anything, however, it's something I wouldn't (and don't) do myself.