Riddle Me This

In automotive wiring BLACK does not mean ground. In fact Black IS. a main power feeds.

At the ammeter there is a Black AND a Red. One goes to the alternator, one goes to the battery. Both are 12v.

You need to follow and trace out all cirs from battery / alternator to ground. Ground is typically the car body.

There are exceptions like the dome light cir which runs a wire from the door switch (which grounds out when you open the door)to the bulb, then from the bulb ultimately to a power source.