wire connecting

[Peter0003]

Hi All, I was think of wiring up a indicator buzzer just like I had on my 2Cv. The wiring is a different size on my K11 1998 model more like usb cable wiring, so when connecting exterial wiring to the car wiring which is better solder the wire to the green/yellow wire or a anything else.
also I have a cigarette lighter which is not coonected and have two black connections not atteched to anything directly behind siad unit, any idea what there for. Peter0003

 

[nissan boy]

Not just replace the relay with a noisey one? Like a bike one or something ,
And one will be for the lighter (it's looks like a L ) or which ever fits and second , depends on what it is plug wise