DCC DECODER

[Anonymous]

I just put a decoder in my Atlas Alco RS-3 and it seems to work fine, but the wrong light comes on, (when I go backwards the front light comes on and when I go frontwards the back light comes on) what did I do wrong?

[Javern]

yellow wire is for rear light, blue is common, and white wire is for front light

[Bikerdad]

The yellow and white wires are not hooked up correctly, or the loco's light boards aren't wired with the appropriate colors. It's no big deal, you can usually remap the CVs so that CV34 refers to the rear light, not front, and CV35 refers to the front, not rear. I know this because I had to do it. Double check the CV indentities, 'cause I'm doing this from memory. [^]

[rrinker]

Or the motor leads are reversed. If the yellow and white wires are hooked up correctly, try swapping the orange and grey.
If the front and rear lights are connected tot he correct wires, you should NOT have to change any CV for function mapping. If you do that - WRITE IT DOWN because you have set up the decoder as non-standard and in the future when you forget about how you installed the decoder in that engine 3 years ago, you will wonder why it acts wierd. The only time you should have to change a CV for basic direction information is to change CV29 for normal direction of travel (NDOT) in the cases where the manufacturer builds the loco to run one way, and your road ran them the other - like Proto2000 GP-7's, LL sets them up to run short hood forward but more roads than not ran them long hood forward. If you install a decoder and run it in forward, it runs towards the short hood, and that light comes on. Add 1 to the value in CV29 and it runs in the long hood direction or forward, with the proper light coming on each time.
If the lights and direction are out of sync, and the lights are not wired incorrectly, the motor leads need to be reversed.

--Randy