I have a very strange problem with the ignition switch on my 1971 1200. The engine will no longer turn off when I turn the key to the off position. I've checked the wiring under the dash and everything seems to OK. I've even replaced the alternator, still didn't help. No changes to the wiring was done to cause this happen. It went from working to not working.
What is strange about this is that if I pull the main connector off the dash pod, the ignition works and the alternator charges properly. If I reconnect the dash pod, the ignition switch no longer turns the engine off. However, if I ground the green wire to any other ground source (see the photo), then the ignition switch works. There are no breaks in any of the circuit traces on the dash pod. If I remove the charge lamp, then the ignition switch works. If I put the tranny in reverse, the switch also works. If I turn the signal light on with the ignition in the off position, the engine is killed. If I pull the windshield washer motor switch, this also kills the engine when the switch is in the off position.
Looking at the fuse box, there's a 10A fuse circuit labelled as "meter/reverse/regulator" on the fuse panel cover. When I pull the fuse, it kills the engine when the switch is in the off position.
The alternator has two ground wires attached to the Earth terminal. Both have good connectivity.
I unwrapped part of the wiring loom between the 4 blade ignition switch and the fuse box. Everything checks out, no broken wires or intermittent short when pulling or wiggling the wiring loom.
I pulled the ignition switch apart and cleaned the terminal contacts. They look good. The switch has a good positive feel in all of its positions. The blade connectors are all solid and making good contact between the switch and the connector.
After all of this troubleshooting, I'm wondering if its still possible that the ignition switch is the source of the problem.
Unfortunately, I don't have a spare switch to try. 4 blades switches are no longer available from RockAuto. They only have the 5 blade switches which is quite a bit bigger than the 4 blade switch.

Any suggestions as what to try next?

Attach file:

---

  c-DSC_5166.JPG (52.15 KB)