What was found
KEF - FLT 893 - EN ROUTE FRA-PHL - CREW RECEIVED THE LEFT GENERATOR DRIVE LIGHT AND DISCONNECTED THE IDG. THE APU WAS STARTED AND RAN FOR APPROX 15 MINUTES, AFTER WHICH IT PERFORMED AN AUTO SHUTDOWN. THE FLIGHT DIVERTED TO KEF AND LANDED WITH NO FURTHER INCIDENT. MAINTENANCE REPLACED THE LOW OIL PRESSURE SWITCH AND RAN THE APU FOR AN HOUR ON THE GROUND. THE AIRCRAFT WAS RELEASED FOR FLIGHT WITH THE LEFT IDG ON MEL. (M)