For some reason, I had connected pins 4 & 13 on the arduino instead of pins 2 & 13. This exhibited the following behaviour:
- DC 14.8V output to track
- Only one programming track light was lit on the motor shield
- Putting the loco on the programming track set it running when POWER button was pressed.
I’ve now successfully programmed the two locomotives I have on hand with their long addresses (3972, 4472).
Next task is to connect the arduino to the layout and see if it drives it!