You may be right TT about an added wire, all my tail light/ rear blinker green wires attach to one black gound wire from the harness with the multi plug.
You must be mistaken about that. An SOHC4 Honda wire harness will never have a black wire used within it as a Battery NEG connection. Anything can be modified, of course. And, peripheral devices can have non-Honda substitutes.
Take a look at Key switch connections in the wire diagram. Red wire from battery POS gets bridged to the Black wire distribution in the harness. Green wires all have a connection to the batt NEG terminal, mostly via the frame's metal conduction path.
But how do you explain the black wires coming from the horn, winker buzzer, winker flasher, rear brake switch, ignition switch etc. They all have a black and no green for ground. One of them has to go to ground eventually.
Every power consumer on the bike must have two paths to the battery terminals via some method.
Functionally, it doesn't matter if you break the NEG path or the POS path it interrupt current flow in a circuit. A circuit consists of a power source and a user or power consuming device, connected by two primary current pathways.
The horn always has 12V on the black wire (key switched on), the other horn terminal goes to the horn button and connects to the bars (frame ground/batt NEG) to make the horn sound.
The winker flasher routes power to the signals at intermittent intervals. At rest, it powers the grey wire exiting out of it which is then distributed to the bulbs eventually downstream. So, the black wire for that is at +12v when key switch is on. When the turn switch is activated, current flows, and the flasher knows to turn the grey wire on and off intermittently.
The rear brake switch is open when at rest. Activate the switch and it routes the waiting 12V on one of its terminals to the the other Green/yel which routes to the stop lamp element, The base of the bulb completes the path to the Batt NEG via the designated Green wire.
The ignition switch (key switch) doesn't need any ground, as it is not supposed to consume power, only distribute it, from the Red wire to the Black wire. It's the draw bridge by which electrons can reach between wire conduction pathways.
The kill switch (could be called the ignition switch, I suppose) Receives switched power from the Key switch (black wire), and passes it on the the coils (Black/White). There is no ground or Batt NEG connection needed for that function. It's another draw bridge and is not supposed to draw power in the circuit.
I did notice black wires with green bands on the rear-end harness, and after what TT said about the grounding i'm kind of nervous about those.
If the green bands look factory and you can trace them back to a bulb socket housing connection, then they rightfully connect to the bike's Green wire distribution.
Cheers,
