Red positive black negative. Probably pull them from radio. The green one is signal wire which depends on which micra you have. On the facelifts its a blue wire on the speedo clock plug
In my Haynes it was the blue one but theres also another diagram (I'm guessing for later models) which seems to suggest it would be a Blue/Yellow wire. There is also a Purple one which goes directly to the ECU, I don't know if you can use that one though.
I’m having the same issue here, tried the blue wire with black stripe, blue wire with green(or yellow) stripe and still doesn’t read the revs, don’t understand why it doesn’t work with the blue and black wite