As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AFTER TAKE-OFF OUT OF ILN, AIRCRAFT FAILED TO PRESSURIZE AND CONFIGURATION WARNING HORN SOUNDED. CHECKED LT OLEO SWITCH, EXERCISED SWITCH SEVERAL TIMES. CLEANED AND RESEATED CONNECTOR. CREW ASSISTED IN GROUND OPS CHECK OF PRESSURIZATOIN AND CONFIG. WARNING SYSTEM. GROUND SHIFT SYSTEM OPS CHECKED GOOD IAW DC-9 MM.