As I ease back into N scale, I'm learning more about installing DCC decoders in Kato locos. Kato takes sort of a middle-of-the-road approach to lighting functions in both N and HO -- it offers ditch lights, which some other manufacturers don't, but they're lit from a single light bar, so they can't be turned on and off separately from the headlight, and they won't flash alternately. You can fix this with extra work, but so far, I'm not inclined to do it.
Here's a TCS K0D8-A decoder that I recently installed in a Kato P42:
There are lots of ins and outs with Kato lighting, even with the simplified representation. I get a lot of inspiration for working in N from YouTube (and for those who make a standard lament that no young people are coming into the hobby, I would counter that a lot of middle school, high school, and college-age modelers and railfans post videos there). But one thing I note is that few guys install the headlight lenses and numberboards that come as "user installable" on Kato N P42s. They're easy to ignore, but they make a small difference:
One thing that's missing from the Kato N P42 is red tail lights that light up in reverse. However, based on what I see in prototype YouTube videos, their use varies. When P42s run in reverse on passenger trains, such as when there's a cab car. NPCU, or another loco on the front, the red tail lights are normally lit. However, this may depend on the particular rules in effect on the territory. Distributed power freight units on the rear of trains don't have tail lights, and what you normally see is the headlight facing rear on dim with no ditch lights -- this is a standard rule indicating the track is occupied.
I've seen P42s running on the rear of trains on YouTube with the headlight on dim facing rear and no red tail lights as well. I also see YouTube videos of prototype light engine moves on the CSX Boston line with the unit facing rear with both headlight dim and ditch lights lit, but no red tail lights. (This is also a reminder that light engine moves do happen on Amtrak and can add variety to model operation.) I programmed the TCS K0D8-A decoders on my Kato P42s to allow the headlights to dim in reverse:
Note also that DCC allows the headlight to be turned off completely on the trailing unit.
The slightly newer Kato N MP36 has headlights-ditch lights that light forward and red tail lights that light in reverse:
The MP36 also comes with numberboards and headlight lenses installed.
The Kato N Sumitomo cab cars have headlights-ditch lights that light when the car is running forward on analog DC and red tail lights that light up in reverse, again on DC. With DCC, both sets of lights are constantly lit.
Kato supplies a limited-function FL12 decoder that allows the headlights and tail lights to be controlled in DCC. I haven't installed one in the car above yet.