First thing I'd do is wire up each pickup to a jack and tap them just to eliminate the possibility that the pickups themselves are faulty.
Second, as I know older EMG pickups, the pickup leads have a braided section that is soldered to ground, and inside that is the hot wire, which is has white insulation. In the above pic, I don't see the hot from the pickup going to the proper leg of the pot at all. Maybe there's something I'm missing, but going by the picture, that's the major problem I see. I'd also tape over the exposed leads on the red battery wires, to prevent them from touching/shorting something when the wiring is finally packed into the bass body.
These look like older EMG JJ, which aren't the current solderless system that is documented on the EMG site now. With the older ones, you had to solder the white (hot) to the middle leg of the pot, then when that was done, you'd solder the silver coax to the top of the pot. IIRC, EMG stuff came ready to go, and the leads were trimmed so you could easily install them this way. In your case, unsoldering, removal and wire stripping would have to happen, which can be done with patience and slow going.
If you don't get what I mean I'll post a little diagram.
"I taught them everything they know, but not everything I know" - James Brown
Last edited by 20db pad : 01-28-2013 at 04:58 PM.