2R by design has left and right wheel isolated so there is no short in 2R. Engine and tender. Normally the switch for steam can control how the left and right tender wheels connect via the switch. Depending on the model, the engine wheels may not factor in for 3R pickup. The switchers usually have the front coupler that complicates the wiring available for power.
If your after 3R only, there are methods to link the left and right engine wheels to gain better outside rail continuity. Same with tender and bypass switch. G
