There are two pinouts that I know of, one for diesel and one for steam. Why they went with two different standards will forever be a mystery!
Just take your ohmmeter and ring out the tether. For a diesel, make sure you get the matching master unit tether.
John, This does not make sense, especially under a Slave discussion. Generic tether are pass through, the PINOUT is not different, just the wire color and gauge. Yes Steam engines have different pinouts depending on model, lots of variation to engines 5V, 3V, MUX, board in tender, board in engine etc...
As far as Diesel ABA Slaves, the connecting harness in still pass through. Pin 2 is Pin 2. The color and gauge did change from 5V to 3V as I mention above.
The later 3V is more traditional in wire color selection. Wht and Yellow motor leads, purple PV, Blue PCB ground, etc... G