I have a sketch - but it is at work. Have to wait till Monday.
Power is available to the change relay and the speed warning unit coils when the time the key is ON.
The change relay coil is grounded anytime the bike is in gear via either contact on the changing switch.
The speed warning unit coil is grounded anytime the bike is moving slower than 16 MPH.
The change relay when OFF:
- provides power to the neutral bulb
- provides power to the starter magnetic switch circuit (which needs a ground via the start button to work)
- blocks power from getting to the speed warning unit/solenoid circuit
When the change relay is ON:
- removes power from the neutral bulb
- removes power from the starter magnetic switch circuit (can't run the starter motor when in gear)
- provides power to the speed warning unit/solenoid circuit
The solenoid circuit is then completed via the contact is the speed warning unit.
The problem I had figuring this out - and also today - is that the speed warning unit has four wires going to it. The picture in the service manual only shows three wires - making the service manual pretty much impossible to figure out. The schematic shows the four wires. I only figured this circuit out by combining the info from the schematic with the picture in the service manual.
Have you tested the solenoid? Mine will open/close with a 9v battery.
Others have found the vacuum check valve to stop working.
Have you checked the dashpot?
Based on my interpretation of the schematic, if your neutral light goes OFF when you put the bike in gear, then at least part of the changing relay is working.
