CUSTOMER CONCERN The hybrid system will not complete high-voltage precharge and stores DTC P1B77. CAUSE The 12-volt battery failed a load test and the high-voltage safety plug measured open, preventing the 12-volt-controlled battery contactors from completing precharge. CORRECTION Remove and replace the failed 12-volt battery and open high-voltage safety plug, clear DTC P1B77, and verify contactor operation, precharge completion, and READY mode.