As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIRCRAFT WAS GROUNDED: IN CRUISE WHILE CROSS FEEDING TO BALANCE FUEL, THE NUMBER 1 AFT LOW PRESSURE LIGHT DID NOT ILLUMINATE WHEN THE SWITCH WAS TURNED OFF. ALSO, THE MASTER CAUTION DID NOT ILLUMINATE. TROUBLESHOT ISSUE PER FIM 28-22-00-810-803. FOUND NUMBER 1 AFT PUMP SWITCH S4 TO BE DEFECTIVE. REMOVED AND REPLACED S4 SWITCH, PER AMM 28-22-43 & SWPM 20-83-11. OPS CHECK GOOD AT THIS TIME.