TIU Problem

I would bypass the TIU and see if the Z4000 right throttle will dim/brighten the caboose lights when you move the throttle.

If so, the TIU is the issue.  If not, its the Z4000 or some other wiring fault causing constant voltage to leak to that loop.

Thanks rplst8. I already did that test  bypassing the TIU and both Z4000 throttles worked fine. So I know the problem is with the TIU, specifically in connection with the fixed voltage 1 channels.

Is it possible that I blew a fuse in the TIU?

The Broskowitz book talks about fuses getting blown and how to replace them, but I don't know if the problem I have could be caused by a blown fuse.

Arnold, I'm sorry I do not know anything about the wiring on your layout. However my first instinct was if you have 2 transformers; they are possibly out of phase. That and a poor common (neutral connection) could create this condition.

Since the fuse is in the voltage path. If the fuse blows you would get no voltage.

Arnold, do you use aux input power to power up the tiu? Does the voltage problem on the z4000 go away if you unplug that aux power input?

Can a TIU be reset to its factory defaults? If so, how?

There is a new development with this mystery.

The right throttle of the Z4000 (connected to the Fixed Voltage IN 1 Channels that powers the outer main line) is now responsive, but the voltage and amp readings are weird. Now, when I move that right throttle, the engine will speed up and slow down  and when I turn the throttle to turn off the power, it shut off the power to the track (good news). I also ran a PS3 locomotive using DCS on that same 0outer main line, and it ran fine (more good news).

However, when the engine is running at a moderate speed, the Z4000 says the voltage is zero, and the amps are between .8 and 1.0, when it should say the volts are approximately 12 to 14 and the amps are approximately 2.0.

The left throttle of the same Z4000 (connected to the Fixed Voltage IN 2 Channels) that powers the inner main loop works fine and the voltage and amp readings are normal when running a locomotive.

Anybody have any idea what is going on?

Arnold

@Fast Mail posted:

Arnold, I'm sorry I do not know anything about the wiring on your layout. However my first instinct was if you have 2 transformers; they are possibly out of phase. That and a poor common (neutral connection) could create this condition.

Fast Mail, you helped me solve the mystery, and I thank you profusely for doing do.

I read your reply earlier this evening, slept a couple of  hours, then woke up and said to myself: check the common wire connection on the transformer.

At first, I only checked the wire connections to the TIU, not the Z4000. The wire connection to the common terminal for the right Z4000 throttle seemed OK,  but it turns out it wasn't fully seated in place. When I loosened and re-tighted it, the throttle and the volt and amp readings returned to normal.

Was I ever relieved, especially because TIUs are not that easy to come by these days.

The loose wire connection to that Z4000 common terminal may also explain why the engine suddenly sped up and derailed to begin with.

Arnold

Good to hear