# Strange Consist Behavior



## spikedrivingblues (Dec 11, 2018)

I recently bought two HO scale BLI SD40-2s which I consisted together. One is a Paragon 2 and the other a Paragon 3.

Everything is fine except for one thing...every time I turn on the DCC system (NCE Power Cab) the rear loco has one ditch light out. When I clear the consist the ditch light on that loco is lit again. Then I re-consist the two locos and the ditch light remains on.

Any thoughts on this strange phenomenon would be appreciated.

Thanks!


----------



## cv_acr (Oct 28, 2011)

It's normal that certain functions are programmed to not come on on non-lead units...

e.g. normally you would not have headlights and ditch lights lit on trailing units, and sounding the horn or bell on sound units would only trigger for the lead unit, not all units, etc.

However it's odd that *one* of the ditch lights is out when one is on, since those should be on the same decoder function output...


----------



## spikedrivingblues (Dec 11, 2018)

cv_acr said:


> It's normal that certain functions are programmed to not come on on non-lead units...
> 
> e.g. normally you would not have headlights and ditch lights lit on trailing units, and sounding the horn or bell on sound units would only trigger for the lead unit, not all units, etc.
> 
> However it's odd that *one* of the ditch lights is out when one is on, since those should be on the same decoder function output...


Thanks for the input That makes sense. Strangely enough, most, if not all, of the functions work on the rear loco (even that one ditch light eventually). The two different horns, bells and motor sounds is terrible so I set the rear loco to mute and use all sound functions on the lead loco. 

However, I like the fact that both locos use all lights, it's more prototypical I believe.


----------



## cv_acr (Oct 28, 2011)

spikedrivingblues said:


> However, I like the fact that both locos use all lights, it's more prototypical I believe.


It's kind of not actually; only the lead engine would have the lights on, and bell and horn would only sound on the lead engine.

Enabling/disabling of controlling functions via the consist address are handled in CV 21 and 22. Take a look at the table of values here: http://www.digitrax.com/support/cv/#cv21_22

If a function is enabled in CV 21 or 22, then when you activate that function for a consist address, it will activate for that locomotive as well, even if not the lead unit. If that function is disabled in CV 21/22, then it will only activate when you address that loco directly, or it's the consist leader.


----------



## spikedrivingblues (Dec 11, 2018)

cv_acr said:


> It's kind of not actually; only the lead engine would have the lights on, and bell and horn would only sound on the lead engine.
> 
> Enabling/disabling of controlling functions via the consist address are handled in CV 21 and 22. Take a look at the table of values here: http://www.digitrax.com/support/cv/#cv21_22
> 
> If a function is enabled in CV 21 or 22, then when you activate that function for a consist address, it will activate for that locomotive as well, even if not the lead unit. If that function is disabled in CV 21/22, then it will only activate when you address that loco directly, or it's the consist leader.


Thanks for that info and the link. I will check that out. 

Sorry if I'm going off into the weeds here but I model CSX. I have watched many videos and have seen several CSX trains operating around my area. Locomotives operating individually have their rear light on even when moving forward so it follows that locos behind the lead loco would have lights on as well. I'm sure this is not true all the time but I have seen it quite a bit.

I'm certainly not arguing with you as I have limited knowledge of model trains and real trains alike, rather hoping to learn more about this topic so that I can add another element of realism to my layout.

Anyway, thanks again for that info about the cvs. that sounds like it will help me a lot!


----------



## cv_acr (Oct 28, 2011)

Running individually or in consist is a bit different. You certainly don't need lights in the middle of the set, only the ends. And mostly only in the forward direction of travel. (Yard jobs and locals doing a lot of switching may have lights up on both ends, a through freight train only needs front headlights. Ditch lights are usually only used on the front end travelling over the road, and turned off in yards.)


----------



## spikedrivingblues (Dec 11, 2018)

cv_acr said:


> Running individually or in consist is a bit different. You certainly don't need lights in the middle of the set, only the ends. And mostly only in the forward direction of travel. (Yard jobs and locals doing a lot of switching may have lights up on both ends, a through freight train only needs front headlights. Ditch lights are usually only used on the front end travelling over the road, and turned off in yards.)


Thanks! That will add some realism to the layout!

I've been busy with work so I haven't got a chance to check out that link yet but I hope to tonight.

Do you know if those cvs are the same for BLI?


----------



## spikedrivingblues (Dec 11, 2018)

Never mind. They are. I forgot all about the trusty owners' manual :laugh:


----------



## cv_acr (Oct 28, 2011)

Those CVs are part of the DCC standard.


----------

