Yamaha XS750 1977 charging problem

[tHiBoB]

Hello
to all. I am new to the forum. I did some research on the forum but couldn't find the answer to my problem. I am finalizing the threading of my 1977 XS750. I have installed motogadget m-unit. The bike runs well. However, the charging system is not working. I have a green, brown, black and red cable as well as three white at the output of my RR. Towards my stator, I have a green cable and a brown one. Brown is a 12V. On the other hand, I have no idea for green. It is not a 12V current nor a ground. What is the function of the green cable?

Thank you

tHiBoB

 

[tHiBoB]

hello I continue my research. According to some wiring diagrams, the brown wire coming from the RR must be connected with the black coming from the field coil. The green wire coming out of the RR must be connected to the green of the field coil. But I am hesitant. Usually black is use for a ground. The third wire from the field coil is suppose to be a yellow for lightning purpose. Anyone can confirm that to me ? Thank you

 

[tHiBoB]

I have 3 wires from the field coil (black, green and brown)