What was found
AT 27,000 FT ON DESCENT, TURNED ON ENGINE ANTI-ICE- GOT NR 2 TRANSFER BUS OFF LITE AND SOURCE OFF LITE, NO BLUE GEN BUS OFF LITE. NO CB'S OUT. DID QRH- STARTED APU & PUT ON RIGHT SIDE PER QRH. SOURCE OFF BUS WENT OUT- STILL HAD TRANSFER BUS OFF LITE. PUT GRD POWER ON AT GATE - TRANSFER BUS OFF LITE WENT OUT & BLUE GEN OFF BUS LITE CAME ON. GROUNDED - YES. ACCOMPLISHED B737-800 FIM 24-21 TASK 822 & TASK 823. NO FAULTS NOTED. PERFORMED ENG IDLE RUN AND ALL A/C IND NORMAL. TRANSFER BUS OFF LT & SOURCE OFF LT REMAINED EXTINGUISHED. NO HISTORY 30 DAYS.