Oops. You're right, the green power indicator LED is the one at lower left. The middle red LED turns on when the relay is successfully triggered (relay clicks on).
Well, this is quite the pickle!
Above shows my experiment. Again, I don't have a FT turnout and am proposing a method that turns on the relay with +5V DC and turns off the relay with -5V DC. As shown in the photo I was able to reliably trigger the relay with as low as 2.5V DC. And at 5V DC the current required from the yellow wire was only 1.5 mA which I'd think the FT turnout can supply; but this is an assumption.
If you have not abandoned ship (yet),
1. confirm the silver band on the diode is oriented as shown. btw, what diode are you using?
2. disconnect the yellow wire and touch the left side of the diode (without the silver band) to DC+. This applies 12V to the IN trigger and should fire the relay for sure!
3. can you read the white markings on the component I call R5 - should be 3 digits like "222".
4. do you have a voltmeter?
My diode I think if I am reading the marking right are 1N400. Diode is connected correctly. When I touch the left side of the diode to DC+ I get an almost imperceptible flash from the middle LED . I think my R5 resistor is 302.
So Since I bought a pack of these relays I took out another one and YAY, I got it to work. The relay LED turns on when I touch the diode to DC+. But when I connected the diode to the yellow wire, I got just an imperceptible flash from the relay but no click. Oops! I forgot to touch run a wire from the AC GND to DC-. So NOW the light switches color BUT flipping the turnout switch does not change the color. Should I be connecting the diode to the switch or to the turnout itself? So it seem that the yellow wire does not go on or off. It seems to be in a steady state.
I do have a voltmeter.