https://apps.dtic.mil/sti/tr/pdf/ADA147208.pdf
BRADLEY INFANTRY FIGHTING VEHICLE PROCEDURES GUIDE: COMMANDER AND GUNNER (FEBRUARY 1984)
PDF Page 19, says that step #7 in shutting down the turret to exit the vehicle is to MOVE TO OFF...the STAB SWITCH.
This is a manual from
1984, for the M2A0 -- we know this because the M2A1 was not introduced until 1986.