I just purchased an otherwise nice Squire Shepard Fairey "Obey" Tele, but I think I have a grounding problem. When I touch the strings, I get a hum. The input jack has been replaced and a poor job of doing it. Is there a positive/negative wiring to the jack? In other words, does it make any difference which of the two wires goes where to the jack? I also see an unattached white wire that I think is coming from the humbucker, but I don't see where it was attached to the pots or switch (possible extra wire from the pickup?). I'll have to look closer tomorrow but though I would ask for help from you guys. In the "support" section of this site there is a diagram for an Amer. Fat Tele, but not my guitar. Would the wiring be the same since I'm dealing with a humbucker and single pickup setup on both?
Thank you!

A pic of the inside wiring would help immensely.

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problem fixed. The jack wires are + and -. Mine were switched incorrectly.