Pin_A is B+. Pin_B or Pin_C will ground the dome lamp. Remove wire from Pin_B to see if problem goes away. If not, reinstall wire and remove wire from Pin_C.
No B+ feed wire on TURN/BU fuse. B+ is supplied via bus bar. Bus bar feeds TURN/BU fuse, BLOWER fuse & RADIO fuse.
Download the 88 wiring. Should be close enough for 86.
https://comancheclub.com/topic/12083-electrical-manual/
Cubicles are like cages without bars. One good thing is that your computer is more important then you, therefore you get AC in the summer and heat in the winter. Stay away from the snack machine, resist.