I just got a GP 40 loco and would like to have sound with it can this be done and ho hard is to add.

I was running two trains both DCC from one E-Z Command Control center. while running a new 2-6-0 Mogul locomotive the power light and the light beside the number 1 started to flash and both locomotives stoped like the stop button was pushed. I checked both locomotives and found that when I placed the tender of the new locomotive on the track is when the lights would flash. I also found that this is the same thing that happens when some metal object falls across the tracks. Just as I decided that there must be a short circuit in the tender the lights on the E-Z Command controller went out and the unit does not work. should there be a short circuit detection devise between the E-Z Command control center and track. has any ever had this problem?