Hello, I'm posting here first, in case my understanding is wrong and the issue is not really an issue. I'm driving a tandem of AC4400CW locomotives on Sand Patch in TSW3 on PC (from XBox store). If I understand correctly, the MU Headlights knob should be set in "Long Hood Lead" for the lead loco and "Long Hood Trail" for the trailing loco. Yet, when set on anything other than "Single or Middle Unit", the headlights do not work at all. And if set on "Single", the lights work as if the loco is solo and not a tandem (as it should). I checked and the SD40-2s and GP38-2s work as expected. Labelling is slightly different, and says "Controlling" and "Controlled" instead of Lead/Trail, but the idea is the same: when properly set, the "Front Headlight" knob will control the front headlights of the lead loco, and the "Read Headlight" knob will control the rear headlight of the trail loco. I haven't tried connecting different locomotives in tandem (i.e. an AC4400CW with an SD40-2 or GP38-2), because mixed tandems do not usually appear in scenarios. So, am I correct in saying the above is a bug for AC4400CW? Cheers! P.S. Why is the forum insisting on changing the capitalization? I wrote AC4400CW, but it was changed to Ac4400cw, MU to Mu, and even M.U. to M.u.
You have it backwards: it's "short hood lead" (i.e., the short hood is leading) and "short hood trail" (same same)
Backwards how? The locos are back-to-back. I'm in the lead loco. Which settings do I choose? And which setting do I set in the trailing loco? Because the text on the knob seems to say I have to set "Short/Long Hood Lead" in the Leading loco, and "Short/Long Hood Trail" in the Trailing loco.
Changing the leading loco to "Short Hood Lead" allowed me to get front facing Headlights. However, there are no rear headlights, and I tried both Short and Long Hood Trail in the trailing loco.
Eureka! The rear headlights do not work if completing the setup while coupled to a train. They work as you said if the setup is completed while uncoupled, i.e. just the tandem are coupled together, but not attached to a train. I tested this in the free play scenario (Cumberland Switchback). I coupled two AC4400CW locos, set the lights like you said and both front and read headlights turned on. I then proceeded to couple the tandem to some cars, to see if the read headlights would turn off when coupled, and they didn't. However, after I turned everything off, then back on, while coupled to the train, the rear headlights would not come on, same as it happened in the timetable service I was playing before.
It would have been cool if the rear headlights turned off when coupling to a train. They don't. It's just that turning on the lights has no effect while coupled, which is how you start most of the scenarios and timetable services. Seems inconsistent to me, far from cool.
If you want to see something cool, check out how the ditch lights adjust with the reverser. Unfortunately, these lights are not synchronized for a tandem, so only the leading locomotive flips the lights when reversing.
Don't know about TSW3, but in TSW2020 make sure the DPU breaker is closed on the lead engine (it also enables MU) and the two top rows of breakers are open (turned off) on the trailing engine (actually at least DPU and Radio must be off). Only then can you control the trailing headlights from the lead engine. I've discovered that as I had turned DPU off, thinking there's no helper, but that disabled MU altogether.
Nope, that didn't work either. The only way to turn on the trailing loco's lights from the lead engine is when you're not coupled. So, if you start a service (e.g. G089) with the locos already coupled, you either drive off without rear lights, or uncouple, turn lights on, then couple back. Also, if you do this, do not turn off the rear lights, as they cannot be turned back on while coupled. One could argue that there's no need for rear headlights when coupled to a train, and that's fine with me. I just wish the functionality was consistent, i.e. lights go off whenever you couple to a train. Now, if anyone has time to play with these things, there are more inconsistent behaviours when AC4400CW loco is the lead in a tandem with other locos. For example, service Q352 has AC leading a GP38-2, while service Q249 has the AC leading a SD40-2. As you can guess, the behaviour is inconsistent for these as well. In one case, the rear lights are on at all times (regardless of the position of the control knob). In another case, the rear lights won't turn on at all. Lots of fun to be had while playing with these. Anyway, I think I will leave Sand Patch for a while and return to Clinchfield and the F7.
