What was found
MAIN CABN DOOR EICAS LIGHT ILLUMINATION AT FL380 WITH CARGO DOOR OVERHEAD LIGHT ON AS WELL, DIFFERENTIAL PRESS STEADY 8.1PSI, CABIN ALT APPROX 6500. LIGHT WENT OUT ON DESCENT INTO DIVERT FIELD FL190. RELEASED FOR SERVICE PER MEL : 52-71-01-02 CATEGORY : C. MAIN DECK CARGO DOOR INDICATION SYSTEM INOP. VERIFY AND RECORD IN AML/EAML THAT MAIN DECK CARGO DOOR IS CLOSED, LATCHED, AND LOCKED BEFORE EACH DEPARTURE. MEL 52-71-01-02, DEFERRED MAIN CARGO DOOR INDICATION USING MEL 52-71. REMOVED AND REPLACED S892 SENSOR REF. AMM 52-71-09-2. CONFIRMED GAP OK AND INDUCTANCE TO BE CORRECT AT 5.8MH. DOOR CLOSES, LATCHES, AND LOCKS CORRECTLY IAW AMM 52-32 00-2.