I have a W.K. Vanderbilt tender G scale , 948 . I don't have the engine . Trying to check if it has sound ? I put a 9Volt battery in it , then attached a train transformer to it , via the wires .It does make noise . But it's just noise ! Does the engine produce the sounds and the tender is just a speaker ? Just what sounds should it make anyhow ... a chuffing steam engine sound ?
THANKS !

The noise you hear should be "white noise" like you get from an AM radio tuned between stations.  The chuff sound is created by making and breaking the electrical current to the sound generator (circuit board).  Try hooking up the wires again; this time touch them together momentarily, and then bring them apart.  With the right timing, this should sound like the chuff that you're looking for.

Once you have an engine, the drive mechanism should have a make/break device that will replicate the appropriate timing of the chuff.

Best of luck,
Jay

Hi You do not need the transformer, only the battery.  Using the lead wires that go to the locomotive touch them together momentarily and you will get the actual chuff sound.  If the wire has the plug on the end use a small jumper wire to insert in the plug and you will get the chuff sound.  Jay is correct the locomotive has a chuff sensor on it and when the lead wire from the tender is plugged into the locomotive and you run the locomotive you will get the chuff chuff sound.

Here is a link to my article on the loco and tender, scroll down to the so the sound troubleshooting paragraph for more details. https://www.bachmanntrains.com/home-usa/board/index.php/topic,30394.msg224039.html#msg224039

Have fun,  Loco Bill