I'm using TCS decoders. My question is how do I arrange the lighting when operating in a consist. What I want is two locomotives, coupled tail to tail to operate so that the only light on is the headlight in the lead locomotive regardless of what direction the consist is traveling. All the other lights in both locomotives would not be lit. The rear light in both locomotives would never be lit in such configuration and the headlight in the rear locomotive would only light up when the direction was reversed. I read the TCS instructions but find them somewhat confusing.
If using NCE Power Cab no need to change the CV's in the individual loco's Just setup a advanced consist in the power cab and the power cab will handle turning the forward facing light on in what ever loco is in front and the rest off. and when in reverse it will do the same in reverse.
What command station are you using? What consisting method are you using? As David Wolf noted, this is pretty easy with an NCE system. If you have any other system, this is not easy. I have a Digitrax system, and the way I do this is as follows. I use "hard" consists (sometimes called "basic" consists), which means that I set each DCC address for locos in the consist to the lead engine's address. I set up the lead engine to have its headlight on in either direction (F0 forward and F0 reverse) and I move the rear light to a free function key (usually F3). Then I set up the rear unit of the consist for the "normal" F0 behavior: headlight on in forward, headlight off in reverse. This engine will also need to be set up for "reverse" running in CV29. I also set this unit up so that the rear light never comes on by reprogramming F0-reverse. For any "middle" units, I turn off the headlights completely by programming F0 accordingly (removing headlight functions from F0). This works great if you don't break up consists during operating sessions, or use "nested" consists (for example, helper service). Breaking up a "hard" consist means that you will need to reprogram the DCC address for your consisted units, and also reprogram the F0 behavior described above. The other way to do this with Digitrax is to use Advanced Consisting, which requires you to set a 2-digit advanced consist address in CV19. Then you can program CV's 21 and 22 in each decoder to tell the decoder how to respond to function keys when using the Advanced Consisting address. For the lead unit, you want it to respond to both F0-Forward and F0 Reverse, so program CV22 with a value of 3. The middle units you don't want to respond to anything. Use a value of 0 in both CV21 and 22. For the rear unit, you set up CV22 so that it responds to F0-Forward, but not F0-Reverse. To do this, program CV22 with a value of 1. John C.
