I'm not sure what kind of engine a "D9" is, but assuming it has headlights on the front and back, do they both respond the same? Like are they both bright when stopped, but dim as the engine moves, or does one headlight stay bright?
My guess, based on what's been said and the fact that the light does work and is doing the same thing each time, is that a CV is set incorrectly. For example, most decoders allow you to set the lights so they are bright when the engine is moving, but dim when stopped. That usually means you can set it for the reverse - bright when stopped, dim when moving.
I'd check the CV or CVs that control lighting options, or maybe just bite the bullet and do a factory re-set.
I have a dozen MRC decoders and dirty track/wheels/bad connections can cause them to loose their brains. I reprogram them and everything works again.
Me too, cept for this issue. Headlight is full brightness at standstill, and gradually gets dimmer as speed increases. I've checked everything. Decoder and all connections are hard wired. No clips. Voltage seems to be shifted away from the headlight and over to the motor as the motor revs up.
Sounds like a wiring issue. Perhaps the lead to the headlight has come in contact with one of the leads up from the track. Check the little black plastic clips that hold the leads on Athearn wiring for a stray wire that is contacting where it shouldn't?
Mike Lehman
Urbana, IL
I have an MRC decoder in an Athearn Ready to roll D9. When I turn on the headlight, it comes on at full brightness. As the loco begins to run forward, the headlight gets dimmer as the speed increases. At full speed, the headlight is out complately. Somehow, something is draining the current away from the headlight. I'm going to replace the decoder, probably with a Loksound, but I'm curious about the light dimming issue, if anyone can shed any light on it.