Hard for me to believe that a PS/3 SW1500 is pulling two amps just sitting idle on the track, there's certainly something wrong there.
I have a 3V PS/2 SW1500, it pulls about 1/10 of an amp just sitting silent on the powered track. When I do the startup, it bumps that up by almost another tenth. Yep, that's less than 1/5 of an amp with the audio idling. At 55 MPH, it was pulling around 1/2 an amp. This is with no cars, just the locomotive.
If I had a similar locomotive that was pulling 2 amps on the track, I'd be finding out what is wrong with it! That seems way excessive.