I did some testing went onto HSC in TSW 4 free roam did the tests in the yard at south fork yard and branch ... Here is what worked . First tested the UP SD40 2 spawned 3 of them ran fine light power and with some cars. 2 tested NS GP38 2 worked good with and without cars. 3 UP GP 38 2 same results as NS 38 2. 4 MP36 baby bullet with and without cars 5 F40ph 2 cat worked with and without cars 6 tested EWS class 66 in HSC coupled to 5 us box cars worked the CSX Clinchfield GP 38 2 SD40 SD 40 2 DID NOT work
Works: CN GP9RM HSC GP38 HSC ES44 SHERMAN HILL SD40 SD70ACES (need to flip screen fuse off/back on) SPG AC4400 SPG C40-8W CC AC4400 CAJON ES44 CAJON SD40 (Both of these have alert audio bug) CCR F7 (will randomly shut down and won't restart) Might be missing a few. Can use Sd40 ccr or csx sd40-s if spawned by timetable mode. Delete the consist and make your own. 99% of time for me when I hit set path the game crashes Also I've been running into an issue with Set Path not functioning correctly on most routes.
I also tried the clinchfield SD40 did not work for me the engine would start moving on level track brakes fully applied and revesr in nuetral only stopped when i put into emergeny brake ..I also posted and tested cause lots of people get disappointed with the Us content and think most locomotive dont work but with the above list show s that there are a fair number that do work in free roam on tsw 4 and to use them you have to have or get certain DLC s plus now i know which one work so when i want to tinker around with free roam then pick the ones i know that run
I also got the MP36 and F40ph Cat to work tried the MP15 it ran some but certain things made it operate not just right had to keep holding brake release to run brakes wouldnt fully release havent tried the F40ph 3c from boston sprinter yet will try that today