Circuit Description
The purpose of the accessory power module (APM), integral to the starter/generator control module (SGCM), is to control the amount and direction of energy flowing between the 42v DC and 14v DC Buses via the APM, bi-directional 42v DC to 14v DC converter. During all of the APM functions the voltage is closely monitored between the internal voltage and the 12-volt underhood battery for voltage correlation faults.
Conditions for Running the DTC
| • | Engine is running for 30 seconds. |
| • | The SGCM has received voltage on the ignition 0 voltage circuit. |
| • | The SGCM has turned ON and no configuration DTC is present. |
| • | This diagnostic shall run every 100 milliseconds. |
Conditions for Setting the DTC
APM voltage is not equal to 12-volt battery voltage +/-2 volts.
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 (DIC), 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. |
Step | Action | Values | Yes | No |
|---|---|---|---|---|
Schematic Reference: Starting and Charging Schematics Starting and Charging Schematics Connector End View Reference: Engine Electrical Connector End Views Engine Electrical Connector End Views | ||||
1 | Did you perform the Engine Electrical Diagnostic System Check? | -- | Go to Step 2 | |
2 |
Is the DTC set as current DTC? | -- | Go to Step 3 | Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems |
3 | With a scan tool, compare the 12-volt Converter Output Data from the SGCM data list, with the Desired Accessory Power data in the HPCM data list. Is the data parameter within the specified value? | +/-2 volts | Go to Step 5 | Go to Step 4 |
4 | Test the battery positive circuit from the Underhood Fuse Block to the starter/generator control module (SGCM) including the 175-amp fuse for an open, short to ground, or high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 7 | Go to Step 5 |
5 | Inspect for poor connections at the harness connector of the SGCM. Refer to Testing for Intermittent Conditions and Poor Connections Connector Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 7 | Go to Step 6 |
6 | Replace the SGCM. Refer to Generator Control Module Replacement . Did you complete the replacement? | -- | Go to Step 7 | -- |
7 |
Does the DTC reset? | -- | Go to Step 2 | System OK |
