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 auxiliary power outlet (APO) function will convert 36-volt DC bus power to 120 volts A/C. 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 A/C voltage will represent the A/C voltage measured at the output of the APO inverter. This signal will have the following specifications: |
| - | Range 120 volts AC, +5 percent, -8 percent, at 20A |
| - | Frequency 60 Hz +/- 0.25 Hz |
| - | Provide 120 volts AC at 60 Hz energy for ON and OFF board electrical equipment. |
The following DTCs are for external 120-volt A/C 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. |
DTC Descriptors
This diagnostic procedure supports the following DTCs:
| • | DTC B139A DC/AC Converter Input Voltage Low |
| • | DTC B139B DC/AC Converter Current Sensor Low |
| • | DTC B139C DC/AC Converter Current Sensor High |
| • | DTC B139D DC/AC Converter Output (Single or 1) Current High |
| • | DTC B139E DC/AC Converter Stuck OFF |
| • | DTC B139F DC/AC Converter Stuck ON |
| • | DTC B140A DC/AC Converter Output (Single or 1) Ground Fault Performance |
| • | DTC B140B DC/AC Converter Output (Single or 1) Ground Fault |
| • | DTC B140C DC/AC Converter Performance |
Conditions for Running the DTC
| • | Engine running for 30 seconds |
| • | The SGCM has received voltage on the ignition 0 voltage circuit. |
| • | The SGCM has turned ON and no configuration DTC are present. |
| • | This diagnostic will be run every 1.12 ms. |
| • | Reference voltage is stable and accurate. |
Conditions for Setting the DTC
| • | B139A DC/AC converter input voltage low. |
| • | B139B DC/AC converter current sensor low. |
| • | B139C DC/AC converter current sensor high. |
| • | B139D DC/AC converter output 1 current sensor high. |
| • | B139E DC/AC converter stuck OFF. |
| • | B139F DC/AC converter stuck ON. |
| • | B140A DC/AC converter output 1 ground fault circuit performance. |
| • | B140B DC/AC converter output 1 ground fault detected. |
| • | B140C DC/AC converter performance. |
Action Taken When the DTC Sets
| • | The powertrain control module (PCM) stores the DTC information into memory when the diagnostic runs and fails. |
| • | The malfunction indicator lamp (MIL) will not illuminate. |
| • | The driver information center, if equipped, may display a message. |
Conditions for Clearing the DTC
| • | A current DTC Last Test Failed clears when the diagnostic runs and passes. |
| • | A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other non-emission related diagnostic. |
| • | Clear the DTC with a scan tool. |
