What was found
AFTER APU BLUE LIGHT ON, TRIED TO PUT IT ON LT AND RT TRANSFER BUSSES, WOULD NOT CONNECT UNTIL CYCLED SWITCH TO RESET POSITION. ACFT GROUNDED. ACCOMPLISHED "APU GENERATOR OFF BUS LIGHT ON WITH APU GENERATOR ON LINE" FAULT ISOLATION, REF FIM 24-21 TASK 801, NO FAULTS NOTED. DUE TO HISTORY, R & R P5-4 "AC SYS GENERATOR AND APU MODULE" AS PRECAUTIONARY, REF AMM TASK 24-21-51, GROUND FUNCTIONAL TEST NORMAL.