Railsounds upgrade

The chuffing effect is usually enabled by a cam sensor on a wheel set or a magnetic sensor reading a magnet on a wheel set or by a secondary circuit in the sound system called a voltage controlled oscillator.  Without additional information on the original loco and tender it's hard to answer your question on what the unused wire is for.

Since it came from a steam locomotive, I don't think it'll be a VCO, probably a chuff switch somewhere.  That green wire probably went to the chuff switch in the locomotive.

quote:

Since it came from a steam locomotive, I don't think it'll be a VCO, probably a chuff switch somewhere.  That green wire probably went to the chuff switch in the locomotive.

Maybe.  If it's original equipment.  If it's an add on, who knows.

I don't think I've ever seen a factory steamer with a VCO, so at least half the statement is correct.

You're right about the add-in, all bets are off as to what the wire does, I was just providing a "best" guess.

As Chuck said we need more info. For the green wire you can follow the instructions here

http://www.lionel.com/media/se...ents/72-2960-250.pdf  and here 

http://www.lionel.com/media/se...ents/72-2963-250.pdf. 

Bill