Tone pot for P bass doesn't do anything

you have to remove the pick-guard and see what has been done. My guess is that it has been completely bypassed. That was not that uncommon a mod way back when - - there was a time when folks got it into their heads that having the tone pot & cap in the circuit sucked "tone" out of your signal. Silly, but folks did some silly things back in the late 70's / early '80s.

 

lol. i've even seen people just run the pickup straight to the jack and forget the volume and tone all together.

 

I've done that. At the time I rarely used to volume control and to this day I rarely touch the tone pot. I usually use passive electronics and I like a clean signal chain. I'm thinking of putting a six position switch with caps in in place of the tone control on my P-Bass to see if I like it.

To the OP, it could be that the cap dried out. No cap means no RC circuit for low pass.

KO

 

Depending on how it's wired - if the cap is grounded to the side of the pot, it can be very easy to break the connection when replacing the pickguard.