Tail Light wire gauge?

SAnyone know the gauge of the wires that run to the taillights? specifically the solid green wire that operates the running lights. Finally found out why I have brake lights but no tail lights. A section of that group of wires sustained some damage near the spare tire and the solid green got cut somehow. I'll need to solder in piece of wire there and it looks smaller than 18 gauge. I thought most automotive wire was 16 or 18 gauge but this might be 20 or 22. If anyone knows for sure I'd appreciate it. Thanks

 

I just pretty much just use 14 Gauge for any vehicle but for trailer brakes.

All the Harnesses I built for the swaps .

bigger is better .