I don't know about the smoke....
but is the positive lead ran through the wc115? It has a current sensor that when current is detected, it switches from run in speed to set speed on the gun (wire feed speed).

Does your have a contactor?
Mine did not, so I bought one that had a 24v coil and installed it myself, the bobcat has to be in run for my contactor to close when I squeeze the trigger.