I just purchased my first DCC ready locomotives (no command controls in place), from a local antique / Junk(?) store.  One of the locomotives is a 10-wheeler, the other more recent purchase is a Decapod.  Love these locomotives, They are both Bachman Spectrum.  I also purchased a neat Vandy tender, also Bachman Spectrum and DCC ready. 

Running the locomotives is sooo sweet, very smooth.  I seem to have a problem though with the Vandy tender.  When I connect it up to the Decapod, it runs in reverse direction from the 10-wheeler and just about every other locomotive I have.  Where do I start with trouble shooting this kind of problem.  I have tried reversing the trucks, but the loco wouldn't run.  There are two very small plugs, I have no idea which plug does what.  Could I reverse connections on a couple of the wires?  Which ones???

Thanks for your input - Big Geyser