I have just installed new lights in a locomotive of mine. The forward light works perfect, but I can’t get the rear one to come on no matter what I do. I touched the positive to the forward light positive, and it came on. I tried remapping it to the default, resetting it, and even remapping it to the green wire and attaching it to that; but still nothing. Are the green and yellow wires BOTH disconnected from the plug? It’s a TCS T1 decoder, can anybody help me?
Tyler,
You should have the yellow (rear) and blue (common) wires connected to your rear headlight. The blue wire is common for both front and rear headlights.
- Front - white and blue
- Rear - yellow and blue
Tom
That’s the way it’s currently connected. It’s properly grounded, because when I touched it’s positive to the forward positive, it came on.
Tyler,
Did you test the bulb itself to be sure that it’s good? Sounds like that’s what you were saying but I wasn’t sure.
Tom
Yes, when I touched the rear light’s positive to the forward light’s positive, the rear light turned on.
Green? On a TCS T1, the green and purple (I think) wires are not used. The blue wire goes to both, white to the front, yellow to the rear.
Forgive me if this seems obvious, but some guys are new to DCC and not aware that they have this level of control. You need to turn on the lights with F0, or they will be off. With this decoder set up with defaults, the front light will only be on when going forward, and the rear light will only be on when going backwards. (Note that some decoders will flash the rear light, even when going forward or stopped.)
I don’t think the T1 behaves this way, but some decoders required you to start in motion before the lights will come on. QSI’s sound decoders work this way.
Examine the plastic coating of the decoder. Is there a pinhead-sized black spot anywhere on it? This is a sign of a burned-out function. If you connected up a LED without a current-limiting resistor, you might have burned out the LED and/or fried that function on the decoder. If you shorted the output of the function, you almost certainly fried it.
And the good news? It’s a TCS. They’ve got a goof-proof warrantee. Or, you can install this decoder in an F7 that doesn’t have a rear headlight.
I know. I tried yellow, but it wouldn’t work, so I tried to use green. By “not used” I think they mean that they aren’t assigned anything. I didn’t think of the “starting in motion” theory, but the front light doesn’t do it, so I assumed the rear light doesn’t either.
I have actually had this problem with another T1 decoder; in my C40-8W. Unfortunatly, I don’t have an F unit, all mine are dummies.
Maybe I will swap it with a different kind that’s in my P42. I think it’s probobly out of it’s warrenty. Actually, I have another T1, which I got a few days ago, maybe I will use that one.
Thanks,
For a TCS T-1, and all other brands of decoder that comply with the NMRA wiring color code standard, you should connect the blue wire to both the front and rear lights. Blue is the positive output to both lights. The white wire connects to the forward light and the yellow wire connects to the back light. Both lights are directional, meaning that they come on as the throttle is set for forward or reverse motion.
The white (headlight) wire is controlled by CV 49, which should have a value of 0 as its default.
The yellow wire (backup light) is controlled by CV 50, which should have a value of 16 as its default.
Sometimes, the throttle has to be turned up slightly before the lights will come on.
That’s the way it’s connected. I tried everything, and concluded that it must be a bad decoder. I have also had this problem with another decoder, both purchesed a few years ago, so it must be a bug in the software.
The wiring is correct; I swapped it with a new T1, which I got a few days ago, and it worked perfectly. I’m using the old one in an Athearn SW1500.