Wierd engine name change and TIU issue

Improbable.  My first effort would be to check all wiring, including ground, for abreak or loose connection.

Bob,

Factory reset and then 're-adding' the engine restores all functions except the name on the display is strangely changed to "ST N&W J" .

The name change is an easy one.

Odds are that when the board was replaced 10 years ago, it was replaced with a used board from another engine and whomever did it added a Custom Name for the engine, rather than use the Service Loader Program to change the board's permanent name. Is this the first time that you've Factory Reset the engine since the board transplant? A Factory Reset erases the engine's Custom Name in that DCS Remote. Just use the DCS Remote to re-enter it.

If you do a Factory Reset via the App, the same thing will happen.

Is it possible that my rev L TIU is bad?

I suspect that the transceiver board in either the TIU, the remote or both may have partially floated out of its socket. Test this by connecting  a 4-conductor telephone handset cord (the curly kind) between the base of the remote and the TIU's Remote Input port. If things improve, we can proceed from there.

This and a whole lot more is all in “The DCS Companion 3rd Edition!" This book is available from many fine OGR advertisers and forum sponsors, or as an eBook or a printed book at OGR’s web store!

Now I'm back at my computer.

My above answer is based on your statement that the onset was sudden and many locos are affected.

With a Rev L, all black output terminals should be connected together.

A factory reset changes the loco name to what has been stored in the board initially.  Could an earlier owner  or a tech of yours have replaced the board in the loco?  They could have used a board pulled from another loco.  I wouldn't bother with another factory reset:  just change the name to what you want.

After a track signal test, if loco is silent, hit the up volume button a dozen or more times.

Make sure you do not have any loose connections at the TIU output to track, same with track connection. No new accessories or passenger cars add that can kill DCS Signal?  If that all checks out, open TIU and look for loose internal connections on the terminal post.

As Barry stated the name is a mute issue.   You can add it back with a custom name.  If not any of the issues Barry or I stated, you could have a defective TIU or channel.  Move to a different channel to see if that fixes ST issue, or ideally swap TIUs.   G

Re naming the engine with a service replaced board now makes sense and it worked. Thanks Barry.

After several hours of chasing connections, testing theories and re cleaning the track, I noticed a loose battery in the remote. Signal restored to normal.

Happy 4th to all.