As MrDeb says after your message, TINA does simulate this circuit well. It does work.
Thank you so much all of you. Hope this helps others out too. What a nightmare!
I added a phototransistor as the other half of a photocoupler and a second led and resistor as an activated led.
Angie's happy again.
One question though. This is with a 5k6 resistor, one wagon? I simulated 10 wagons (5k6 is parallel) and the simulator says it still works. What problems or failures etc could I experience, if any, as I don't know what readings to take from the circuit to select the correct components.?
Should the diodes be able to handle 16v at 3A as that's the current each block will have (max)?