Make sure your Legacy version is 1.6 at the base and 1.61 at the remote otherwise the system will change the sensor car to Legacy commands only. Also all TMCC commands must be recorded in TMCC mode to a TMCC engine. I have one sensor track that is used with an early Legacy engine that is recorded for various sounds and then an engine startup and run with sounds sequence for a TMCC Lionmaster Challenger. The Challenger has its own sensor car and runs another recorded sequence when passing over an outer sensor track.
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