Failing to properly configure the polarity for 2-rail operations will result in the
locomotive starting in reverse instead of forward or not receiving the DCS
signal. Should this occur, it is not necessary to swap the wires from the
transformer to the track or reverse the locomotive’s orientation on the track
itself. Instead, simply slide the polarity switch shown in Figure 6 below in the
opposite direction. For the configuration and polarity shown in Figure 5 the
DCS Polarity switch should be towards the front of the locomotive.
Premier SD90MAC Diesel Engine with PS-2 and Proto-Scale 3-2
6
Ensuring Proper Power to Track Polarity
Changing Track Polarity Inside the Locomotive
For 2-rail DCS operation, it is important that the polarity from the transformer to the
engine is properly configured. Correct polarity can be accomplished by ensuring that
the wiring from the TIU to the track and orientation of the locomotive when sitting on
the track follows the illustration in Figure 5.
To TIU Black Terminal
To TIU Red Terminal
DCS Polarity Switch
Locomotive Front
Locomotive Rear
