how can i unlock my rear brakes after the ABS ligth comes on

ABS SYSTEMS WILL NOT NORMALLY CAUSE YOUR BRAKES TO LOCK UP YOU HAVE SOMETHING ELSE GOING ON AN ABS EQUIPPED VEHICLE IF ABS FAILS YOU ALWAYS HAVE MANUAL BRAKES ABS WILL ALLOW YOU TO STILL STOP YOUR ABS CONTROLS ARE ALL ELECTRICAL SENSORS AND PUMP MOTOR WITH AN ABS CONTROL UNIT

Hi Not knowing your skill level is a major factor,as a technician for 27 yrs i can say i never remember a bimmer locking up for an abs issue.However i have seen plenty of bimmers towed in with wrong brake fluid Hope noone put power steering fluid in brake reservoir.