I have the Hogwarts set, and I upgraded it to TMCC. However, I was always very disappointed in the original Dementors coach, it was pretty lame. The new version is much cooler, great sounds and lighting effects. One little problem. It gets annoying if it runs all the time, so I decided to add TMCC switching so I could enable the sounds on demand. That worked out great, a simple conversion. One little problem! When you turn off the power to kill the sounds, the lights are turned off as well! Since the lighting effects are a big part of the show, I didn't want to separate them from the sound module. What to do... what to do...
I got it, I'll just add my own lights! Now it has two sets of lights. The overhead set comes on when you first power up the car, that's the default for the ERR MiniCommander ACC board. That's perfect, works like a normal car until it's enabled. In order to enable it, I just turn on the sound module and turn off the overhead lighting, all by remote control from the TMCC remote. When it's time to turn off the sound, I can just turn on the overhead lights and turn off the sound module the same way.
Cool beans, so this is what I ended up with. The only outward change is the RUN/PGM switch for the MiniCommander.
In order to have flicker-free lighting, I used one of my lighting modules to drive the lights.
This is a nice easy conversion and solves the problem of turning off the sound but still having lights.