Where does this wire from the firewall bulkhead connector go? (see pics)

[TW97C1500]

I don't remember and can't find where this single brown wire from the firewall bulkhead connector goes.  I had looked at another truck, a 96, and thought I had it, but when I got to mine, it won't connect there.  The other one must have had some option mine doesn't.

[Mikebtte]

Test it for power, it may not go to anything. Could have been for another option or something your not equipped with.

[Renee Benner]

Did anyone figure out what the wire is for and where its suppose to plug in at? Because i've been wondering the same thing

[Jeremy-WI]

I think that wire has power when the key is on for some dual battery relay