As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING FINAL TO LAND, LEFT BRAKE PRESSURE GAUGE INDICATED RESIDUAL PRESSURE OF 500 PSI. PUMPING BRAKES MADE NO DIFFERENCE. RAN RESIDUAL ALTERNATE BRAKE PRESSURE CHECKLIST. DECLARED EMERGENCY. BSCU REPLACED IAW MM 32-42-72 AND SELECTED SWITCH REPLACED IAW TSM 32-42-00. OPS TESTED NORMAL.