Circuit Description

The starter/generator control module SGCM unit is an electronic device that works in conjunction with the electrical subsystem to efficiently perform DC/DC and DC/AC electrical energy conversion and support vehicle functions. The primary mission of the SGCM unit is to:

• The auxiliary power outlets APO function will convert 36 volt DC bus power to 120 volts AC. If the value of APO mode is OFF, then the APO function will be disabled and the APO Converter/Inverter will not transfer or consume any power.
• The APO output AC voltage will represent the AC voltage measured at the output of the APO inverter. This signal will have the following specifications:
  • Range 120 volts AC, +5%, -8%, @ 20A
  • Frequency 60 Hz +/- 0.25 Hz
  • Provide 120 volts AC @ 60Hz energy for on and off board electrical equipment.

The following DTCs are for external 120 volt AC harness failures, excessive current loads or internal system failures within the SGCM.

• B139A Output voltage of the converter is too low to meet current APO mode.
• B139B Value of APO current is less than 60 amps.
• B139C Value of APO current is greater than 60 amps.
• B139E APO commanded ON, but the converter remains OFF.
• B139F APO commanded OFF, but the converter remains ON.
• B140A Internal SGCM circuit to monitor the ground fault detection.
• B140C APO is disabled due to improper DC bus input voltage or excessive internal temperatures.