YING WITH AVIONICS RAMP CHECK COULD NOT ENTER SYSTEM MAINTENANCE TEST MODE. Resolution: THAT AIRCRAFT NUTCRACKER SYSTEM WIRING HAD BEEN MODIFIED TO NON STANDARD GIV WIRING. UPON INVESTIGATION FOUND THAT THE APU POWER 1, APU POWER 2, AND APU POWER 3 CIRCUIT BREAKERS PROVIDE POWER TO THE NUTCRACKER CIRCUIT BREAKER. FOUN