Lionel Veranda turbine smoke units

Yes, that is the way mine operates. The diesel stack (rear) only works when the engine is at or below 25 scale mph, which I think equates to speed step 7. Above that the turbine stack operates on its own, which I think is broadly meant to be prototypical operation. I have not seen the problem you describe; on mine the diesel stack stays off until the speed goes below what I have mentioned. I've never had occasion to check the wiring of the two units but always thought that the on/off sequence must be triggered by a reading from a motor flywheel.

FWIW, while looking for something else I just had a look at Lionel's replacement parts pages for this engine and see that it has what is described as a dual smoke switching motherboard, which must be specific to it. Also, there's a wiring diagram for this engine on the Lionel website and as far as I can see from that switching of smoke unit operation doesn't depend directly on a flywheel sensor. But something in the electronics triggers the switch to the forward smoke unit and the turbine sounds that go with it.

That makes me wonder whether your engine just needs a reset (instructions on page 18 of the manual) to restore the right smoke sequence operation?

Did the reset with #6 as per the manual. At first, it did not do any difference but 2nd time running, it did work as it was suppose to. I've noticed that running increasing the speed very slowly, it turned on the front unit and about a few steps higher, turned off the front and the back one came on again. Ran it again from stop, it worked like it is suppose to but increased the speed slightly more which to me, it does not matter. As long as the Veranda works, I'm happy. It is a awesome piece to own.

Glad you got to something like correct operation. I agree it's a great engine although I'm reminded that others have found the smoke and lighting features a little problematic, as reported on this old thread:

https://ogrforum.com/t...onel-veranda-turbine

I've only ever had the problem with the red hazard light not working and a reset cured that.

A Legacy version is on my wish list. I also wish that Lionel would find some way to put the sound and light features of their old HO version of the Veranda in an O scale version. If you've ever heard the HO Turbine start-up and shut down sequences (there are lots of YouTube videos of them) you'll know why. They put any current Lionel or MTH UP turbine sound sets completely in the shade.