What was found
1) ENGINE #2 LOOP "A" LIGHT ILLUMINATED. "ENGINE OR APU LOOPS LIGHT ILLUMINATED ABNORMAL PROCEDURE COMPLETED."2) TRANSFERRED TO DEFERRAL PER MEL 26-12-01-1. ASSIGNED DMI #11836. PLACARDS INSTALLED. "B" LOOP OPS NORMAL.3) ENGINE #2 LOOP "A" LIGHT ILLUMINATED. ENGINE OR APU LOOPS LIGHT ILLUMINATED ABNORMAL PROCEDURE COMPETED.4) TROUBLESHOOT TO #2 ENGINE DUAL CONTROL FIRE DETECTOR UNIT. REMOVED AND REPLACED UNIT AS PER M/M 26-12-11. GROUND TEST NORMAL. THIS CLEARS DMI #11836.