I wouldn't think it does anything, going to empty pins. Maybe it does something on the 500E upwards. Those models have an EQ bypass and a mids EQ switch.
This is new old-stock (no fret-wear). Listed for sale on talkbass https://www.talkbass.com/classifieds/music-man-25th-anniversary-4-string-bass-hss.1656882/