The car has two power sources; battery and alternator.
Each has a wire that connects to the main circuits at a welded splice.
The splice is hidden in the harness but its important to understanding the system. Power is fed to the splice and then to one of three main cicuits.
1. Fuses that are always hot. (wire Q3)
2. Headlight switch for headlights (wire L1)
3. Key switch. (wire J1)
View attachment 1716233192
Power to the horn is an exception. In '66 its connected at the starter relay.
When engine is running power comes from the alternator.
When the engine is starting, or any time the alternator is not running, power comes from the battery.
