What was found
DURING APPROACH INTO SFO AFTER THE LANDING GEAR WAS EXTENDED, THE LEFT MAIN LANDING GEAR DOOR WARNING LIGHT ILLUMINATED. CYCLED THE LANDING GEAR HANDLE AND ALL INDICATIONS NORMAL. AIRCRAFT LANDED WITHOUT INCIDENT. MAINTENANCE TEST OF NR 1 AND NR 2 LANDING GEAR CONTROL INTERFACE UNITS REVEALED NO FAULTS. CLEANED ASSOCIATED GEAR DOOR INDICATION SWITCHES. OPERATIONAL CHECK OK.