PJ confusion

[ChuckO]

Hey guys, I have been a long time reader but never really a poster. I need some help. I have a PJ bass, I took it to a tech a few years ago because my soldering skills were not quite up to snuff and I had just purchased some quarter pounders.
Well the short version of the story is that he made a mess of my bass, there are tons of extra connections, and with both volumes all the way down, my bass still operates at about half volume. So I practiced some soldering and feel confident that I can do it correctly but he took the initially black and white wires off of the pickups, so how to I tell which one is hot?
I realize the hot wire goes to a pot and the cold goes to a ground but I am not sure he did this correctly because the J pup sounds really thin. So would reversing the hot and colds on the J pup cause this? Sorry for the rambling.

[Steveaux]

It won't hurt anything.

Go for it.

[line6man]

If you still have output with the volume controls all the way down, that would indicate that the third terminal of each pot is not properly grounded, as the pickup hot should be directly connected to ground when you roll the volume all the way down.

Usually the white wires would be the hots and the black wires would be the grounds.

If the pickups were out of phase, they would only sound thin when played together.
If they sound fine alone, it's not a phase issue, so swapping the black and white leads on one pickup will not help.

And FWIW, pickups do not have cold terminals as they are not putting out a balanced signal like a microphone would.
A pickup's leads are simply a hot and a common (Ground).