Bass Tone and Hum problems

[Rotsanjani]

I'm new here and I'm not sure if an issue like this has been posted before. I have a problem with my bass and I can't find someone (Technician) here in our place who can help me. So, I decided to try to learn on how to fix it myself.

I can't adjust my tone. there's no effect/nothing happens no matter how I turn the tone knob.no change of tone. I think there's something wrong with the wiring inside. does anyone have a schematic diagram of the wiring? or maybe just a drawing of how things inside should look like. my guitar is a P-Bass with two knobs, Tone and Volume.