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 42 volt DC and 14 volt DC buses via the APM, bi-directional 42 volt DC to 14 volt DC converter. All APM functions will only be run when in the enable mode. APM current will be defined as the current flowing through the outputs. APM power is bidirectional, with negative current representing 14-42 direction, and positive current representing the 42-14 direction.
When the APM power conversion direction is set to a value of 42 volt to 14 volt, the energy will flow from the 42 volt DC Bus to the 14 volt DC Bus via the APM. When the service charge or jump start is requested, the energy will flow from the 14 volt DC Bus to the 42 volt DC Bus via the APM. When the APM power conversion direction is set to a value of Off, the APM will be turned OFF and not consume or transfer any power. When the APM power conversion direction is set to a value of Invalid, the energy will flow from the 42 volt DC Bus to the 14 volt DC Bus via the APM.
The following DTCs are for internal failures within the SGCM.
| • | P1A93 is for the APM stuck in the OFF position. |
| • | P1A94 is for the APM stuck in the ON position. |
DTC Descriptors
This diagnostic procedure supports the following DTCs:
| • | DTC P1A93 14-Volt Power Module Stuck OFF |
| • | DTC P1A94 14-Volt Power Module Stuck ON |
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 shall be run every 100 ms. |
| • | Reference voltage is stable and accurate. |
Conditions for Setting the DTC
DTC P1A93
14-volt power module stuck OFF when commanded ON.
DTC P1A94
14-volt power module stuck ON when commanded OFF.
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 | Yes | No |
|---|---|---|---|
Schematic Reference: Starting and Charging Schematics Connector End View Reference: Engine Electrical Connector End Views | |||
1 | Did you perform the Diagnostic System Check - Vehicle? | 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 |
3 | Inspect for poor connections at the harness connector of the SGCM . Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs . Did you find and correct the condition? | Go to Step 5 | Go to Step 4 |
4 | Replace the SGCM. Refer to Control Module References for replacement, setup, and programming. Did you complete the replacement? | Go to Step 5 | -- |
5 |
Does the DTC reset? | Go to Step 2 | System OK |
