Hey everyone, I can’t seem to find out how to reverse the headlights using Digitrax 123D decoder. For some strange reason, my Athearn RTR SD40 shows a forward headlight, but travels in reverse! I swapped the truck pick-up’s and that didn’t change anything. I am not able to swap the motor leads, as the IC board mounted atop the motor is fit for the leads. I would like to change the headlight direction, via the decoder if possible, so that when the loco is traveling forward, the forward headlight is on! Any help is appreciated. Thanks!
Hmm, well, it can’t be plugged in backwards because the 9-pin plug only fits one way. The lights being opposite the motor, assuming you made no CV changes, is usually a classic motor leads are reversed situation. I guess it could be wired wrong from the factory. Could be the lighting leads are reversed, too.
Does it move in the right direction when set to forward? If so, it’s the lighting wires that are messed up. If not, you need to add 1 to the current value of CV29 to reverse the normal direction of travel so forward on your controller make it run forward. Assuming this is all correct and the lights are still backwards…
Check CV33 and CV34. By default, CV33 should be 1 and CV34 shoudl be 2. If not, set these values. If it already IS set that way, flip them - make CV33 2 and CV34 2, this will reverse the light functions and make F0F the yellow wire instead of the white wire and vice versa. That should solve your problem. That information is on Page 50 of the Digitrax Decoder Manual.
I think Randy meant to say "make CV33 2 and CV34 1 to reverse the lights. The real problem is that the motor leads are reversed, but if you flip the CV’s for the lights, you will accomplish the same thing.
I looked through the 78 page decoder manual and must have missed this information. When the loco is set for forward direction, the forward light is on, so yes, the motor leads must be backward from the factory.