In DCC, pressing F7 will turn the smoke unit ON and OFF. In DC, use the DCMaster and set CV222 to 21. This makes the smoke controllable by the AUX button on your DCMaster. Next, set CV246 equal to 0. This causes the smoke to be OFF at power-up. Or, if you prefer, each steam engine has a ON/OFF power switch. This is normally located under the cab, and sometimes behind the front removable smokebox cover. On some models, this cover is difficult to remove and you may prefer one of the methods listed above.