Trains.com

Subscriber & Member Login

Login, or register today to interact in our online community, comment on articles, receive our newsletter, manage your account online and more!

Reversing Locomotive Direction

25135 views
38 replies
1 rating 2 rating 3 rating 4 rating 5 rating
  • Member since
    March 2015
  • 1,358 posts
Posted by SouthPenn on Friday, August 14, 2015 10:37 AM

I had an Atlas Trainmaster engine open last night. None of the wiring matches the NMRA color code.

South Penn

South Penn
  • Member since
    September 2004
  • From: Dearborn Station
  • 24,281 posts
Posted by richhotrain on Sunday, August 9, 2015 5:34 AM

SouthPenn

Odd. When I change the 'forward' direction of an engine using CV29, the lighting also changes to the proper direction.

I'm using NCE decoders.

South Penn

 

That's the way it is supposed to work.

Let's say that the value of CV29 is 34 (forward direction, 28/128 speed steps, long address.  The headlight is on in forward and off in reverse.  

Now, if I change the value of CV29 to 35, the loco will travel in reverse and the headlight will be off when I press the forward direction button on my NCE throttle.  If I press the reverse direction button, the loco will travel forward and the headlight will be on.

Rich

Alton Junction

  • Member since
    March 2015
  • 1,358 posts
Posted by SouthPenn on Saturday, August 8, 2015 7:48 AM

Odd. When I change the 'forward' direction of an engine using CV29, the lighting also changes to the proper direction.

I'm using NCE decoders.

South Penn

South Penn
  • Member since
    February 2002
  • From: Reading, PA
  • 30,002 posts
Posted by rrinker on Thursday, August 6, 2015 7:36 PM

 Depends. Do you want to do it right, or change some CVs and then get all confused a few years down the road when you need to reset the decoder and can't remember why the lights and direction are all messed up? That's why I (usually) test before soldering the motor wires and shrinking the heat shrink.

 Or later go back and hook up some other directional function, like ditch lights, and none of the examples in the decoder manual work because - oh yeah, you have to set everything for the opposite of standard.

                   --Randy


Modeling the Reading Railroad in the 1950's

 

Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.

  • Member since
    September 2004
  • From: Dearborn Station
  • 24,281 posts
Posted by richhotrain on Thursday, August 6, 2015 4:56 PM

rrinker

 Hmm, you think they'd have that right in an E7, since it's pretty obvious which end is the front.

Proto 2000 is somewhat notorious for reverse motor wiring.  I have had a couple miswired right out of the box.

Rich

Alton Junction

  • Member since
    February 2002
  • From: Reading, PA
  • 30,002 posts
Posted by rrinker on Thursday, August 6, 2015 3:57 PM

 Hmm, you think they'd have that right in an E7, since it's pretty obvious which end is the front.

 I can see the Geep being backwards, because some railroads ran them long hood forward and some short hood forward, although first gen as delivered the majority were long hood forward. Oh well. At least it's not hard to fix. It's harder flipping the crew figures to face the right way.

                       --Randy


Modeling the Reading Railroad in the 1950's

 

Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.

  • Member since
    December 2004
  • From: Pa.
  • 3,361 posts
Posted by DigitalGriffin on Thursday, August 6, 2015 2:28 PM

TheBAYline

It is off in forward and on in reverse.

-Christian

 



Wire leads to motor are backwards.

Edit: Um never mind.  Saw you solved the problem.  Congrats.

Don - Specializing in layout DC->DCC conversions

Modeling C&O transition era and steel industries There's Nothing Like Big Steam!

  • Member since
    September 2004
  • From: Dearborn Station
  • 24,281 posts
Posted by richhotrain on Thursday, August 6, 2015 1:10 PM

TheBAYline

I reset the decoder, tried swapping the motor wires as suggested and this fixed the issue. The trouble appears to be Proto has their wires miscolored. They have an orange wire for the motor top and black for the bottom, so I had connected decoder orange to engine orange and decoder grey to engine black. By swapping the wires I now have decoder orange connected engine black and decoder grey connected to engine orange, and everything works perfect.

 

Excellent, good job.  Bow

Rich

Alton Junction

  • Member since
    February 2007
  • From: Christiana, TN
  • 2,134 posts
Posted by CSX Robert on Thursday, August 6, 2015 8:42 AM

richhotrain
CV's don't work that way.  

Actually, they do.  Most decoders support some form of "function mapping", which allows you to change which physical output is assigned to each function.

TheBAYline
I just want to know what CV's and what values I need to change to make the white wire headlight turn on in reverse. I'm almost certain that will fix the issue...

Re-mapping the function will fix the problem. Unfortunately, the flexibility of Loksound decoder function mapping also makes it complicated.  I don't have time right now to read through the manual and figure it out.  There are probably people on here with experience with that decoder that could tell you the steps.  If you started a thread titled something like "Loksound V4.0 function mapping" someone with Loksound experience might respond with the correct answer.

  • Member since
    May 2012
  • 48 posts
Posted by TheBAYline on Thursday, August 6, 2015 8:39 AM

I reset the decoder, tried swapping the motor wires as suggested and this fixed the issue. The trouble appears to be Proto has their wires miscolored. They have an orange wire for the motor top and black for the bottom, so I had connected decoder orange to engine orange and decoder grey to engine black. By swapping the wires I now have decoder orange connected engine black and decoder grey connected to engine orange, and everything works perfect.

  • Member since
    July 2006
  • From: North Dakota
  • 9,592 posts
Posted by BroadwayLion on Thursday, August 6, 2015 8:08 AM

Seems strange to LION. LION has "Reversing switch" train goes east or west depending on the position of this switch. Was so easy in DC.

Well, no, wait, LION does NOT have reversing switch on layout of him, because trains of him do not go backwards. LION grounds left rail, puts +8v dc on right rail, train goes forward. Should one want train to go backwards, yo youd put -8v dc on right rail, and train *will* go backwards.... and smash into the one behind it. Trains on route of LION are only a few seconds apart. Is way subway trains run, ewe knows.

Hobby used to be so simple, I am glad LION does not use DCC, him likes simple.

 

ROAR

The Route of the Broadway Lion The Largest Subway Layout in North Dakota.

Here there be cats.                                LIONS with CAMERAS

  • Member since
    September 2004
  • From: Dearborn Station
  • 24,281 posts
Posted by richhotrain on Thursday, August 6, 2015 5:25 AM

TheBAYline

I just want to know what CV's and what values I need to change to make the white wire headlight turn on in reverse. I'm almost certain that will fix the issue.  

CV's don't work that way.  

If the white wire is not connected to the proper physical function output, the decoder programming protocol is compromised. If the white wire is connected to the proper physical function output, there would be no need to revalue any of the CV's.  

So, the first step in the investigative process should be to check your wiring to confirm that the white wire is connected to the proper physical function output. My guess is that you connected the white wire to the rear light function output.   That would explain the headlight going on in reverse and off in forward.

If the white wire is properly connected, then the orange and grey motor wires are probably reversed, in which case you now reverse them again and then revalue CV29.

Rich

Alton Junction

  • Member since
    May 2012
  • 48 posts
Posted by TheBAYline on Wednesday, August 5, 2015 10:10 PM

I just want to know what CV's and what values I need to change to make the white wire headlight turn on in reverse. I'm almost certain that will fix the issue. I even emailed ESU but they haven't gotten back to me yet.

  • Member since
    March 2015
  • 1,358 posts
Posted by SouthPenn on Wednesday, August 5, 2015 8:53 PM

Randy

You could have saved yourself a lot of work and just changed CV29.

South Penn

South Penn
  • Member since
    March 2015
  • 1,358 posts
Posted by SouthPenn on Wednesday, August 5, 2015 8:49 PM

I have a few consist that are permanently connected together. When I need to have an 'A' unit run in reverse as it's primary direction, I just change the entry in CV29. Usually this is just changing CV29 from '35' to '34'. If you're using a NCE decoder, CV120 should be set to '1'. The decoder is smart enough to know when to turn the light on. CV121 should be set to '2' for the reverse light. Press F0 on your throttle to turn the lighting function on. Or press 'Headlight' on a NCE throttle.

Also, if your light is a LED, make sure you have the polarity correct: the blue and white wire are not reversed.

As far as wiring is concerned, you can drive yourself nuts trying to keep the color codes 'by the book'. As long as the Red & Black go to the track and the Orange & Grey go to the motor, your decoder should be able to make the necessary changes. If not, get a different decoder. (my Stewart/Kato 'F' units have no markings on the motor. The motor is buried deep in the frame and a real pain to get out. I just hard wire them and use the decoder to make it run like I want it to.)

South Penn

If you download the Digitrax Mobile Decoder Manual, on page 34 is a chart showing CV 29 values and what they do. AS CV29 is the same in every decoder, all these adresses should work.  

South Penn
  • Member since
    February 2002
  • From: Reading, PA
  • 30,002 posts
Posted by rrinker on Wednesday, August 5, 2015 5:32 PM

 And if it does run the right way on DC - then you want to hook the orange wire to whichever motor wire was connected to the right rain, since the NMRA DC standard says the loco should go forward when the right rail is positive.

 The order of the track pickup wires, red and black, does not matter because the DCC signal is symmetrical. The motor wires, orange and grey, are pulse width modulated DC and polarity there does matter.

 I have 4 Proto 2000 GP-7's. Despite protoypical details INCLUDING the F decal on the long hood, they were all wired to run short hood forward. I had to wire every one of them 'backwards' so they run the right way.

               --Randy

 


Modeling the Reading Railroad in the 1950's

 

Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.

  • Member since
    September 2004
  • From: Dearborn Station
  • 24,281 posts
Posted by richhotrain on Wednesday, August 5, 2015 1:13 PM

davidmbedard
Ok...just rewire it correctly then you will not have to mess with CVs.
 

Whenever I buy a DCC Ready loco, before installing the decoder, the first thing that I do is run the loco on a DC test track.  That instantly tells me if the motor is wired correctly based upon the direction of the locomotive.  If it is running in reverse when it should be running forward, reverse the two motor wires.

Rich

Alton Junction

  • Member since
    September 2004
  • From: Dearborn Station
  • 24,281 posts
Posted by richhotrain on Wednesday, August 5, 2015 12:46 PM

LOL

We seem to be going nowhere fast with this thread.

We are not really getting answers to our questions, so here is my advice to the OP.  Since you have two identical locomotives with two identical decoders, both of which you have hardwired, take off the shells and look closely at your work. Are the orange and grey motor wires wired the same on both locomotives?  Are the white wires wired in the same positions on both locomotives?  

Everything should be identical.  If it is not, that is undoubtedly the problem.  If everything is wired identically, which I am beginning to doubt, then the problem is the CV values in one or both of the decoders.  In that case, reset both decoders to factory default and then re-program both of them.

Rich

 

Alton Junction

  • Member since
    January 2015
  • 257 posts
Posted by RR Baron on Wednesday, August 5, 2015 11:16 AM

TheBAYline

Motor direction on both is fixed, but I still need to figure out how to program the headlight on the one to operate in reverse on the one.

-Christian

 

Don't believe you have actually fixed the problem. You have just compensated for it and moved the issue elsewhere.

The usual suspect for locomotive running backwards is decoder wiring to motor is incorrect. While the locomotive's physical direction of travel can be matched to throttle direction selection using CV 29 or other means it just moves the problem elsewhere, where the locomotive performance or lighting effect depends on the throttle selected direction – forward or reverse.   

 

Check the wiring,  decoder Orange wire to motor positive and Gray wire to motor negative. From what you have written the  connections are reversed.  Also required, decoder Red wire to Right rail pickup, Black wire to Left rail pickup. 
RR Baron

 

  • Member since
    May 2012
  • 48 posts
Posted by TheBAYline on Wednesday, August 5, 2015 9:49 AM

Motor direction on both is fixed, but I still need to figure out how to program the headlight on the one to operate in reverse on the one.

-Christian

  • Member since
    September 2004
  • From: Dearborn Station
  • 24,281 posts
Posted by richhotrain on Wednesday, August 5, 2015 4:22 AM

TheBAYline

Well on NCE systems I just discovered they have a one step fix for backwards running on the configuration menu. It took only a few button presses and it was all switched correctly.

What does this mean?
 
Do you have everything working correctly now?
 
Motor direction and lights?
 
Rich

Alton Junction

  • Member since
    May 2012
  • 48 posts
Posted by TheBAYline on Tuesday, August 4, 2015 10:31 PM

Both of these locos are hardwired installs. 

  • Member since
    May 2012
  • 48 posts
Posted by TheBAYline on Tuesday, August 4, 2015 8:21 PM

Well on NCE systems I just discovered they have a one step fix for backwards running on the configuration menu. It took only a few button presses and it was all switched correctly.

  • Member since
    February 2002
  • From: Reading, PA
  • 30,002 posts
Posted by rrinker on Tuesday, August 4, 2015 7:39 PM

 The RIGHT way to fix backward running it to flip the motor wires. When this is not possible, like when there are no wires to flip because of a board repalcement decoder with motor contacts, like many N scale locos, then is a good time to play with reversing NDOT using CV29.

 Why? Because when the time comes you need to reset the decoder, the default value of CV29 will have it running backwards again, and 3 years from making the change, will you remember that this is how you fixed it? Also the lights issue.

                  --Randy


Modeling the Reading Railroad in the 1950's

 

Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.

  • Member since
    September 2004
  • From: Dearborn Station
  • 24,281 posts
Posted by richhotrain on Tuesday, August 4, 2015 6:13 PM

With two identical locomotives and two identical decoders, it is difficult to imagine one headlight operating correctly and one headlight operating incorrectly.

What is the CV29 value in each decoder?  Are you sure that the white wire is connected to the correct tab on both decoders?  Are the orange and grey motor wires connected in the same position on both decoders?

Rich

Alton Junction

  • Member since
    May 2012
  • 48 posts
Posted by TheBAYline on Tuesday, August 4, 2015 4:36 PM

My E7 model has no rear light, I used the AUX 1 function green wire for the lower headlight and the white wire for the mars light above it.

-Christian

  • Member since
    May 2012
  • 48 posts
Posted by TheBAYline on Tuesday, August 4, 2015 4:34 PM

It is off in forward and on in reverse.

-Christian

  • Member since
    September 2004
  • From: Dearborn Station
  • 24,281 posts
Posted by richhotrain on Tuesday, August 4, 2015 4:04 PM

How does the rear light behave?

Is the headlight always lit, both in forward and reverse?

Or is the headlight only on in reverse while the rear light is only on in forward?

Rich

 

Alton Junction

  • Member since
    May 2012
  • 48 posts
Posted by TheBAYline on Tuesday, August 4, 2015 2:59 PM

Thanks Rich. I ended up fixing both. But now one of them only has the headlight on in reverse. What do I program to change that? This is the white wire on the decoder and is Function 0. 

Subscriber & Member Login

Login, or register today to interact in our online community, comment on articles, receive our newsletter, manage your account online and more!

Users Online

There are no community member online

Search the Community

ADVERTISEMENT
ADVERTISEMENT
ADVERTISEMENT
Model Railroader Newsletter See all
Sign up for our FREE e-newsletter and get model railroad news in your inbox!