what is this plug?

[FreshLikeOprah]

So, I bought my truck in a mess. Stereo was stolen, etc. Some of the factory radio wires where cut. There's two plugs. What is the one on the left for? Steering wheel controls?

 

[OneTwo]

If it's similar to my Suburban, that plug is unnecessary for aftermarket radios except for one wire. The wire is the remote wire for the factory amp, and unfortunately, I don't remember what color it is.

 

[DCT]

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