I can explain about the ignition switch ground and the dark green wire if it helps you to unravel the rat's nest.
1, You don't need the switch grounded, or the green wire, to start the car. They only have one other purpose.
2, The dark green wire goes to the temperature sender. As you start the car and move the key past start, the dark green wire gets grounded. This is what makes the temp idiot light come on as you start the car. This is the idiot light test.
3, The body of the ignition switch needs to be grounded. It's the body that provides ground for the dark green wire.
4, the 64/65 Chevelles have a copper strip that the ignition switch mounted through. This strip is grounded by the original radio mounting screws. Suspect that the Nova is similar.
1, You don't need the switch grounded, or the green wire, to start the car. They only have one other purpose.
2, The dark green wire goes to the temperature sender. As you start the car and move the key past start, the dark green wire gets grounded. This is what makes the temp idiot light come on as you start the car. This is the idiot light test.
3, The body of the ignition switch needs to be grounded. It's the body that provides ground for the dark green wire.
4, the 64/65 Chevelles have a copper strip that the ignition switch mounted through. This strip is grounded by the original radio mounting screws. Suspect that the Nova is similar.
