EDIT: This section was edited out because CO provided us with an official panel to easily adjust our headlights in the asset editor. Thank you CO!

I hope this helps get some of you started on lighting up your trains. TBH, I'm not sure that cars and truck play by different rules than trains. We are still waiting for official information on vehicle lighting so the experiments with trial and error will continue until we get a full explanation. For now this is what worked for me. Going forward, I am on a quest to get the back red lights lit up. The lights seem to work only on the front end of the train cars. All the red lights (the 4 on both ends of the cars) share the same UV coordinates but only the ones on the "forward" end light up. So as a shuttle, when the train goes in reverse, the lights will switch to the forward end. I would love to find a way to get the red lights in the back to be on as all vehicles have this feature most likely for safety and warning purposes....and it would look much cooler. So the quest continues and I will be updating this with any new findings.

Figured I should post this here as well as ST for more exposure.Vehicle light maps play by different rules than buildings. There's evidence that different vehicles may be in different classes playing by rules unique to their classes. Thanks to an experiment by Shroomblaze, we see that we cannot do with a car what we can do with a train with illumination maps. We need official info on vehicle lighting as there is none in the wiki.I will be using one of my trains and what I found on my journey to explain here. It took me days to figure out how to light my trains properly and still needed help from boformer, Don'tCryJustDie and Bloodypenguin to dig for info and adjust the headlights in mod tools. A big thanks to them or my trains would still be dark.The gradient vallues for illumination and neutral diffuse is almost inverted from the values for buildings. Black (0,0,0) is the max illumination color for trains. I used 127,127,127 for the base color of areas not lit. The range below 127 illuminates in the same way the 128-255 illuminates building lights but in the opposite direction. Above 127 will illuminate the diffuse color. I'm not sure what exactly the brighter values do on vehicles but one of my trains displayed half car diffuse illumination when I used 192.Notice the headlight position at default values. More on that in a bit.This is the working illumination map for the cities skylines edition R22 train. The 3 lights are at 192 to illuminate the 4 red lights, the black one is for the headlights. The windows and call sign are around 60-65 and the front window at 86.Now let's talk about headlights.