As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AFTER TAKEOFF ORD, THE NR 2 INS WARNING LIGHT ILLUMINATED WITHOUT ACTION/MALFUNCTION CODES. ALSO, THE NR 1 INS HAD CODE 3 MODE 26 WITH INTERMITTENT CREW FLIGHT/HSI WARNING FLAGS. INS TRANSFER WAS SUCCESSFUL, DUMPED 139,000 LBS OF FUEL AND DIVERTED TO MSP. REPLACED THE NR 1 AND NR 2 INS NAVIGATION UNIT AND TEST WAS NORMAL.