Headlight troubles, or why can't model headlights be controlled as are real ones?

Model Railroader Electronics and DCC
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What follows is a rant.

Why can’t dcc decoders control headlights as headlights are controlled on locomotives in the real world? I was a locomotive engineer for 32 years, in freight, commuter, and passenger, running for Conrail, Amtrak, and even spent some time on Metro-North. I worked on stuff old and new, from RS3’s to SD50’s, from GG-1’s to Amtrak’s HHP-8’s. So… I’m familiar with engine headlight controls and how they’re supposed to be used.

It’s really quite simple:

Most engines have two headlight switches. The positions of each are: Off/dim/bright. (some have a “medium” position as well)

The headlights work independently of one another.

Once you turn one on, it stays as set until you change it.

Easy enough. Sometimes you might set one “wrong” – but that’s still your choice (or mistake!)…

But… models don’t work this way, even with advanced dcc controls.

And … they’re not easily changed over to do so.

It can be done, but it sure isn’t “easy”.

I only have 3 model locos on a small layout (based it on the “Black River Junction” plan that MR put together a few years’ back.

The first is a Walthers SD9 that came with dcc/sound pre-installed. That took a little tinkering, but I finally stumbled on a way to “divorce” the headlights from “directional control” and get them to work individually. Even got them to dim (not individually, but not important).

Second is an Atlas Trainman RS32 into which I put a basic Digitrax decoder. I was able to get the F and R headlights to illuminate independently, although I can’t get a “dim” function to work. At least not yet.

The third is now an older Lifelike (Walthers) Proto 2000 SD9, into which I’ve installed a TCS T-1 decoder. The TCS decoder looks to have several interesting features, but I’m havi

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That’s fairly easy to do with most any decoder - what seems to be the issue? Most decoders offer at least enough function mapping to put the two wires on a different function. And in many case also assign an independent dim function to each one. I would avoid using F1 and F2 for those things though, at least on a sound decoder, because those are by convention the bell and horn. ESU is by far the most flexible - ANY f-key can control ANY wire, with ANY effect and ANY condition. So if you want the white wire on if F3 is on, you cna do that. If you want the white wire to be on, but dim, when F3 is on and F4 is on, you can do that. F5 and F6 for the yellow wire - same deal. So you can turn the headlight on and off with F3, and dim it with F4. Independent of direction of travel or speed.

Check out the Proto Throttle - it even has the two prototypical knobs! Their instructions may also help in configuring decoders because you need to get rid of the automatic direction changing lights and make them indepedent for the knobs to work the way they are supposed to, and they tell you how to do this.

–Randy

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rrinker wrote: “That’s fairly easy to do with most any decoder - what seems to be the issue?”

Heh.

Have you ever tried to actually set an engine up so that the F and R lights function this way?

I can get the “F end” light to come on and STAY on regardless of whether the loco is moving forward or backward.

But I cannot do the same with the “R end”. That light is either off, or when activated by an Fkey, BOTH lights come on. It seems to be “connected” in some way to the F light and directional controls, and I can’t “find the way” to break that connection.

A few very simple questions:

Is there a specific wire that always controls the F end headlight?

The white wire?

Is there a specific wire that always controls the R end headlight?

The yellow wire?

Or… are the “wire colors” something completely “apart from” the lights?

Re: “most any decoder”…

I’m coming to think that the TCS decoder I’m using (T1) is not built to do what I want to do. It seems to have been designed “to make things more helpful” to a general user by linking the headlights/dimming/ditch lights together. But it will not permit independent control of the F and R headlights.

BTW, I’m using a Roco z21 setup (I have both a phone-sized device AND a tablet to work with), and I’m also using the JMRI DecoderPro app.

Having said all that:

On another engine, I used a Digitrax DH126Ps decoder (low-end, actually). But… this one was EASY to get the F and R headlights working independently. The TCS… seems all but impossible.

I’ve read that all decoders were supposed to have the same basic values/whatever.

This DOES NOT seem to be the case in my admittedly limited experience…

I’m not interested in sound in any way. It seemed like a novelty on the first engine I bought, but I quickly gr

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Old E, do you have something else we can call you?

Randy is one of DCC/electrical gurus. I am a newbie but follow these threads in hopes something will sink in. My decoders are loksound and I’m not sure how transferable there system is to TCS

I looked at the TCS Comprehensive Programming Guide. As someone who has never done function remapping, it does not provide any hand holding for us.

It looks like CV 61 is a additive function, meaning you add up different values for differnent things you want the decoder to do or not do, like BEMF, headlight dimming when stopped, dimming when reversed.

CV 123 also controls Rule 17 dimming. Do you have to change both? No idea. If you throw enough information into a post, somebody might know.

Here is the remapping instructions. It doesn’t help me to know how to make the front and rear independant of loco direction

What did you do to make the front light stay on at all times?

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“It looks like CV 61 is a additive function, meaning you add up different values for differnent things you want the decoder to do or not do, like BEMF, headlight dimming when stopped, dimming when reversed.”

I tried shutting off (CV 61 = 0)

Regarding CV 123 and Rule 17 dimming:

I don’t want this to have any effect. Again, for modeling purposes what is called “rule 17” in model forums (and I would guess amongst the dcc manufacturers, as well), isn’t quite the way rule 17 actually worked out on the line or in the yard.

I’ll have to see if I can disable CV 123, but I think I tried this already. I’ve tried a lot of things, often having to do a complete “reset” and start over.

I’ve spent time studying the function remapping (the page you posted above), and only -some- of it is written clearly for folks (like me) who aren’t fluent in “dcc-fu”.

I don’t want to change anything with brake or motor circuits, the engine actually runs smoothly and quietly with the defaults. TCS did good insofar as that goes.

But again, there seems to be no way to set up the R headlight to work independently of the front.

(Aside: the loco I have the decoder installed in is an SD9, which in the real world were set up to run long hood forward, and the decoder seems predisposed to regard the short hood end as “the front”. I can work around this IF I can “get control” of the R end headlight).

Perhaps a couple of images would help.

These are screenshots of the “lights” section from DecoderPro.

First, Digitrax. The menu is very basic and it’s pretty easy to set up individual headlight operation using the popup menus:

(note: I could not post images, but you can see it here):

https://1drv.ms/u/s!An3uN8X2AHdOgmwpcxOZuNqPGCYH

I then assigned the front light to

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My understanding it 0 shuts off BEMF. Not sure that you want to do that.

I use a lokprogrammer not Decoder Pro, but you’ve provided enough information that someone ought to be able to help you.

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A lot of views so far, but not many suggestions.

I figured there would be a few dcc experts here who could clear up this matter pretty quickly.

All I want to do it get full and independent control over the yellow wire (rear headlight).

I can get the white wire working ok, it seems.

But not the yellow one, because TCS seems to have coded their devices so that control of the yellow wire is “entwined” (for lack of a better word I can find) to all sorts of other lighting options. There’s no easy or obvious way to “divorce it” from those options, and to make it “completely free” of everything else.

I’ll keep trying for a few more days, but at this point it looks like my only option is to buy a different brand of decoder, and work from there.

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Why not contact TCS? They have a good reputation for customer service. http://tcsdcc.com/contact

Joe

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This is what I do with a TCS silent decoder.

Train Control System

TCS T4X

Completely independent lights control

F0 = Front light ON/OFF
F1 = Rear light ON/OFF
F3 = Ditch light ON/OFF
F4 = When on Dim litght ON/OFF in the direction of travel
Rear light dim automatically when traveling forward

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JoeinPA – I did contact TCS, and tried their suggestions … no go.

jalajoie – I tried your suggestions above. All I got was both lights would flash when I pressed F1 or F2 (can’t remember which). Other than that … nothing.

Anybody else?

RE: “F4 = When on Dim light ON/OFF in the direction of travel. Rear light dim automatically when traveling forward”

If this is how you have it set up, then it’s not “completely independent light control” and that IS NOT how the lights work on a real locomotive.

Once set, the R end headlight should NEVER change regardless of the direction of movement and regardless of where the front headlight is set.

The two lights should have “no connection” between each other at all.

I’m coming to the conclusion that it’s impossible to replicate this behavior on a TCS decoder. Or at least on the one that I have (T1).

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An approach that should work would be to replace the T1 with a decoder that has at least 4 lighting outputs (instead of the two of the T1).

Assign 4 of your favorite buttons to each of the lighting outputs:

1 will output full voltage–wire it to the front light

2 will output a dimmed voltage–wire it to the same bulb(s)

3 will output full voltage–wire it to the rear light

4 will output dimmed voltag–wire it to the rear light, also

For the front light

1 & 2 off = light off

1 on, 2 off = bright light

1 off, 2 on = dimmed light

1 & 2 on = bright light

For the rear light, buttons 3 & 4 used in the same way.

Operationally, I think I’d normally have both buttons on (for one or both lights). I could then turn on and off button 1 (for example) to go back and forth from bright to dim.

It should work with bulbs. LED’s–maybe not.

As nice as it would be to have a 3 position rotary switch, I don’t see it happening soon.

Ed

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It would appear that TCS won;t woork for this. The dim is a function, not really an effect that can be applied, so there is ooonly one of them, no way to make a dim button individually for each light, just a general ‘dim’ which can dim the active light. Individual on/off is possible, but then the dim button will dim whichever ones are on. Dim when stopped and directional dimming can be turned off. Not sure any with more functions, like a T4, would be any different. However, with more functions, you could take advantage of the way DCC function outputs are designed and combine 2 wires to each light - one with a bigger resistor than the other for dim. Turn on JUST the dim wire, dim light. Turn on the bright wire, with or without the dim wire being on, you get a bright light. Turn both off, no light.

–Randy

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from the description of both the TCS A6X and T4X:

“Dimmable Brightness: Configure multiple different brightness levels for your LED’s or incandescent bulbs.”

Besides 12V, the A6X also has an output for 1.5V bulbs; the T4X does not.

Ed

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Sorry it did not worked for you. I just tested these CV setting with two locos and it does work as advertise for me. One loco is equipped with a TCS T1 and the other a TCS T4X.

On both decoder F0 control the front light, F1 control the rear light, F2 is not in the equation, F3 irrelevent with these locos and F4 has no effect on the T1 while with the T4X lights are bright in the direction of travel and dim otherwise. The behavior of F4 was good enough to me and I did not look further. I think Randy has a good explanation for that.

Your best bet to acheive your goal would be a Loksound Lokpilot V4 decoder or a NCE decoder.

Here are my setting for NCE

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jalajoe wrote: “Sorry it did not worked for you. I just tested these CV setting with two locos and it does work as advertise for me. One loco is equipped with a TCS T1”

Hmmm… I’m wondering if -some other- setting is “getting in the way”. Perhaps something obscure?

I wrote back to TCS tech support, and will give them another day or two for more suggestions before I move to put something else into the loco.

The loco actually runs quite well with the TCS T1. It’s the headlights that I can’t “get control” over. Very frustrating, since it wasn’t a problem with the other two decoders I have (one is a Tsunami that came factory-installed on the Walthers SD9, the other is a Digitrax that I installed into an Atlas RS32).

But using JMRI DecoderPro, I can see right away when I bring up the “lights” panel for all 3 decoders, that the T1 seems to have a problem with getting the two headlights “divorced from one another”. I guess that’s just the “operating paradigm” that the TCS designers decided to run with…

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A reset of the decoder may help.

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Yes, they list multiple brighnesses, but if you look at the function definitions there’s just one 'Dim the lights" function, defaults to F4 but you can change the button. There isn’t a “Dimmer one, F4, Dimmer two, F5” etc. that you assign to different function wires. Linked functions are about the only way with these decoders, but then you need 4 functions for just 2 lights.

Frankly, the automated stuff ends up with the lights set just how you would do it with the individual knobs. Until I get a Protoo Throttle that actually has the proper control knobs, all sorts of extra button pushing doesn’t add anything for me. Stopped or mobing, in either direction, the lights on my loco match what the rules say in the prototype close enough to my era rule book that I have, The best you can do with 2 functions is have each light turned on and off by its own button, and then a button to dim whichever one is on, and no automatic dimming when stopped, and no automatic direction changing.

Except Loksound - and perhaps Lokpilot motor-only decoders can do similar mappings.

–Randy

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Monday afternoon followup:

TCS tech support sent me this:

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Program CV8 ->2 to perform a factory reset. Note that your locomotive’s address will return to 3 if it was not already.

Set CV49 to 40 (this is a omni-directional DIMMABLE light, not ditch light. My mistake.)

Set CV50 to 40 (same as above)

Set CV33 to 4

Set CV34 to 8

What this will do:

Button 1 on your throttle will turn on or off the forward headlight

Button 2 on your throttle will turn on or off the reverse headlight

Button 4 on your throttle will dim either of the lights which are ON. It is not possible to dim one light individually at a time. Sorry.

All automatic dimming is disabled - manual control with button 4

I tested these settings with an identical decoder to yours and was successful.

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Well, guess what?

After doing a full reset and entering the values above, this STILL doesn’t work on the Lifelike/Walthers/Proto SD9 that I have.

The R end light (which the decoder thinks is “the front”) will light with button 1 and stay on when loco moves forward or backward.

But… when I press button 2… (which is the F end light, although the decoder thinks it’s “the rear”) BOTH lights illuminate (again, regardless of the direction of movement).

Button 4 does nothing.

I gave up and ordered a Soundtraxx MC2H104OP (non-sound decoder).

I’ll post a followup when I receive it and install it into the engine.

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Which type of factory board is in that SD9? If it’s the kind with a big resistor in the middle (which has instructions to cut through some traces to install a decoder) - SCRAP IT. Long time ago I installed a decoder in one of those older P2K locos and I inspected to factory board and drew out the wiring diagram and even with the traces cut it is all kinds of screwy. The T1 decoder has a 9 pin plug on the decoder itself so hard wiring it in doesn;t mean you can’t easily swap the decoder.

I typically ALWAYS remove factory lighting boards when adding a decoder - most of the time they are configured for directional constant lighting on DC, don’t need ANY of that circuitry for DCC.

test it outside of the loco 0 just hook the red and black to the rails, and hook lights to the white and yellow wires, blue common to both. Bet the lights work as they say - one button turns on the front light, one button turns on the rear light, and F4 will dim whichever is turned on.

–Randy

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Re dimming, you may need to adjust a CV to regulate how much power goes to the light when it’s dimmed. I’ve had a few times where I thought dimming wasn’t working, but it was just that the CV was set too high. That’s especially a problem with LEDs since they use so little power.

Virtually every decoder defaults to F0 being on or off for both headlights. You’ll need to set up a separate function button for one. Easiest way to do that - and pretty much anything else relating to setting up decoders - is to use Decoder Pro / JMRI.