New pups installed and no tone knob

Check out Seymour Duncan for a wiring diagram.
You should just need a .047uf capacitor and rewire it.
Might be a good time to change all of the pots and wiring depending on the condition andquality. www.stewmac.com and www.basspartsresource.com have nice kits. Just need the standard J bass kit for a PJ.

 

It should be simple enough to rewire the existing pots to convert the Master Volume to a Tone.

http://www.seymourduncan.com/support/wiring-diagrams/schematics.php?schematic=std_p_j_bass

 

If the pots aren't broken, don't fix or swap them. However, you might want to get a couple of varied caps (.022 uF, .047 uF, .1 uF) and see how you like the tone of each.

 

+1. And don't just do the "standard" values wither, try whatever you can from around 4500pF up to 0.1uF, sometimes the cap that sounds best to your ears in your instrument will be a value you'd have never considered. It's happened to me on enough occasions.

--Silvie

 

Use standard American Jazz Bass wiring - just pretend the P pickup is the neck pickup of a Jazz bass and solder accordingly. You can get the schematic on line anywhere: Fender, Seymour Duncan, DiMarzio, Joey's Bass Notes, etc.