Precision Plus craigslist score! And a question about the P Plus . . .

Back for much of the 1990s I played a Fender Precision Plus bass (the 22 fret "boner" bass), and really liked it. IIRC, the P Plus line was about from 1989 to 1995 or so.

My old one had quiet and "hi-fi" P/J Fender Lace Sensor pickups, a great bridge, high quality tuners, TBX tone controls, a button to switch the pickups from parallel to series wiring. The bass as a whole had great sustain and zing. It's one of the few basses I've sold and later regretted.

So I've always kept an eye out for one again, and ten years later darned if one (a 1994 model) didn't show up on my local craigslist this week. So a quick email and car trip later, and it's home with me (pic attached).

So with a new set of DR Hi-Beams installed, the bass plays even better than I remembered! Luxurious low action, and sustain for days. I'm really buzzed about it, and can't wait to debut it at next week's gig.

Now a question . . . I thought all the passive Precision Plus models had the white button between the volume and tone control knobs to switch from series to parallel wiring, as my old one did. But this one doesn't have that button, and yet clearly it's all original, with undisturbed solder joints.

Anyone have any documentation on when the Precision Plus line went from having this button and function to not?

Thanks!