Ignition Switch Short (ignition position ON, red wire to ignition goes dead) 1976 CB750F Super Sport

[RoachCafe]

I have power to the ignition (red wire).

When I turn the key to park, the tail park light works.

Now when I turn the key to on, the entire red (hot) circuit goes dead.
I changed the ignition switch out, same results.

If I pull the black wire out of the ignition switch connection, I have power to the red (hot) circuit again.

I tried grounding the harness black connection with the black wire disconnected from the harness, no change.

I noted that the black wire circuit grounds in through the regulator then out to the green wire to the chassis ground.

 

[drgnrdr750]

Green is ground, not black. A wiring diagram might help you trace the wires

 

[RoachCafe]

Yes, thanx, realized that right after posting this. Car mechanic.

 

[Loki]

Main colours as follows, black ignition switched live, green ground, red permanent live. There is a wiring diagram post on this forum, Hinksy has posted a diagram for your bike.

Loki

 

[RoachCafe]

Thanx. New wire harness waiting to install. Bike was under an oak tree for 20 years. Ran great on first start, developed issue after sitting for 2 years.

 

[Loki]

Just completed a restoration of my harness, untaped end to end, retaped all soldered joins, fixed a few issues along the way then taped it all up again, total cost about half a roll of Scotch insulating tape and several hours on the kitchen table!

Loki

 

[RoachCafe]

Great!
I have an extremely crusty bike that the tank was like Swiss cheese, the seat pan bent in half before throwing in the trash. The harness is very poor. The PO had overloaded a fuse block where the plastic around the fuse melted.
I am eliminating any more hidden gremlins with a new harness from https://4into1.com/ for the cost of filing up my pickup with gas.
https://4into1.com/main-wiring-harness-32100-392-000-honda-cb750f-1975-1976/
Thanx for your support.

 

[Loki]

Looks a bit earlier than mine, can't afford to fill up my pickup these days, 40 gallons beyond my pension!

Loki

 

[RoachCafe]

Yo' no kidding. $$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$

 

[RoachCafe]

Well after all this time, R&R'D entire main wiring harness with a brand new one from 4 into1.
Had to use old 4 connectors due to crap quality of 4into1 harness
Just replaced the starter solenoid because it failed the test.
Bike now TURNS OVER.
Before main harness replacement, it had a major dead short.
Years back, I had gone throughout the bike when received.
It ran great on first riding test.
It sat under an oak tree for 20 years, locked up.