[soccerguy045]

I'm looking at the wiring diagram for my car, and I'm just curious....say there's a tan wire, it says '20 T', I know that the T is for tan, but is the numbering for the gauge of wire? I thought at first it was to help you not get lost with the path of the wire on the diagram, but I see that there is more than one '20 T', for example, and going different places. Thanks.

 

[John_Muha]

The "20" is the size of the wire. It means 20 American Wire Gage (AWG). Cars use stranded wire instead on solid. Solid breaks under vibration.
The color does mean something but GM does use the same color wire in different places. Saved money by buying less different color rolls of wire. In older cars tan was the headlight low beam wire or a low blower switch wire. Probably used another place but can't think of one off the top of my head.