Right now I have a parallel mode on my PJ-bass with two volumes and one master tone controls. Main idea is to making P and J p-ups working together like one big pickup with only one volume and one tone knob, in other words - in series with each other.
P-ups is constructed by russian company named Trakhmann. Very well-made pickups except the design. I know that they uses 4DPT to switching between series/parallel configuration with this combination of pickups. And I also have that "special" switch with cables soldered to pins (see attachment).
P p-up have four conductors - two conductors is "transparent" color (soldered together), one red (HOT) and black (GND). J p-up have four conductors too - green and black (soldered together), white (HOT) and red (GND).
line6man, if you can help me with wiring diagram I'll appreciated it very well.