Another GS4 DCC question

[StewRRFan]

I did not want to highjack the other thread.  I have the GS4 #4431 which I have been told is not one of the problematic 1st run engines.  Works great DC.  I have put the decoder in.  Lights come on but will not move.  On the programming track, JMRI will not find the engine.

Bad decoder or something else?  Thanks for all the help. - Ross

[peteski]

Ross, since you mentioned headlight that sounds like you hardwired it.  Is that correct and  if yes, where are the red and black wires soldered? Did you hard-wire the motor too, or it is still powered through the drawbar?

What brand/model of a decoder?  Did you try running it on DC (assuming the DC mode is enabled - it is usually enabled by default).

[StewRRFan]

I did not hardwire it.  Just removed the stock decoder and put in the Kato EM13.  I have tried it on the DC test track and it does not move.  Thanks Peteski.

[woodone]

The lights come on all buy them self's unless you have changed out the light board and used a decoder with the headlight function wired to the lights. All the lights are telling you is that there is track power. Make sure you have the small connection links in place in the tender. This is where the draw bar wires make contact with the DC board or DCC decoder. Also make sure you have the decoder slid into place under the tabs in the tender.
AND just a note about first run (second run) units!! I have ran into more than one locomotive that was a second run unit that had the driver to frame issue!   
Check to make sure when you touch the wheel at the rear frame you don't see a short.

[peteski]

Ah, now I get it.  The headlight is not wired to the decoder at all, so in DCC it will just be always on when the track is powered.

The plug-n-play decoder installs are tricky because of all those loose contact strips. I would say to just try to remove and reinstall the decoder to be 100% sure all the pieces are in the right spots.  This is one of those times when a 3rd hand would be helpful. 

[StewRRFan]

Woodone -

Check to make sure when you touch the wheel at the rear frame you don't see a short. - What am I looking for here?

[woodone]

You will need a meter to do this- Check to see if you get continuity between the rear wheels ( one at a time) and the orange or gray wire on the motor.
Move the wheel around a bit and press down.
I have had SO  many problems with this locomotive because of the wheel to frame shorts. I now hard wire the motor and isolate the motor 100 % by using wires between the motor and the decoder.

[peteski]

All the loco and tender wheels on each side are electrically connected (the loco picks up electricity throught the drivers and all tender wheels).  If there was to be a short between the left or right pickup and the motor leads, it would nto be just at the tender wheels (but the drivers too).

We discussed this short in another thread and it is caused by a poor design of the sub-frames which are electrically connected to the motor leads. The rear drivers can under certain condition short out to them (causing motor lead to rail short).

While I don't know for sure, I suspect that in this example all the fiddly contact strips are not properly aligned causing an open circuit between either the track pickups and the doecoder or between the motor connections and the decoder.  Just speculating.

I think it is like the problem described in the later part of this post.

[woodone]

The problem is that the lower rear section of the frame is connected to the motor leads- this is also where the draw bar connections are made to the tender.   If you move the driver(s)and they touch the frame you have a rail to motor short. I am by all means no real expert, but after doing about 100 DCC installs on this locomotive I have learned a thing or two.
It has cost me more decoders than I care to admit. I have a second run unit that is my personal locomotive. I installed a DCC sound decoder into it.
No problems, at first. Then about two or three weeks later I went to run it and it would only run in reverse- all the sounds were there but no drive in reverse. So I very carefully took a look at every thing has I removed the decoder. What I found was this, under just the right conditions one of the drivers would touch the rear frame and poof! there went the decoder. So now I remove the leads to the motor that are attached to the frame.
The rear lower frame half's no longer provides power to the motor. I add my own wires and run two extra wires from the motor leads to the decoder.
NO more problems!