Hook the solid yellow wire to one post of the ammeter; either post, just pick one. Connect the yellow/black wire to the other post.
Before installing the instrument panel, temporarily connect the battery. Turn on the parking lights and observe which direction the needle moves (engine NOT running).
If the needle swings toward the "Discharge" side of the ammeter, you have the wires correct.
If the needle moves toward "Charge", you have them backwards.
Disconnect the battery and swap the wires.
Now install the instrument panel and you're done.
You have a 50-50 chance of getting it right the first time. If you guess wrong, reverse them and carry on.
