What was found
GENERATOR SOURCE OFF LIGHT, LIGHT COMES ON BUT NO FAULT LIGHT ON GCU ON GEN 2, SOURCE OFF LIGHT. WHILE TESTING AC SYSTEM, GEN & APU MODULE GEN 2 SOURCE OFF LIGHT CAME ON. GEN 1 WAS ON LINE, RESET GEN 2 & SOURCE OFF LIGHT WENT OUT. GCU 2 NOW HAS AN IDG FAULT. REMOVED IDG IAW AMM TASK 24-11-11-000-801 AND REINSTALLED IAW AMM 24-11-11-400-801. INSTALLATION TEST PASSED AND NO LEAKS NOTED. VERIFIED IDT REQUIRMENTS PER GMM AND AMM 24-11-11-400-801. OK TO CONTINUE. CHECKED WIRING FROM GCU TO IDG AND FROM GCU TO OVERHEAD GENERATOR CONTROL PANEL PER FIM 24-21 TASK 823, NO FAULTS NOTED. R & R GCU IAW AMM.