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 functions of the SGCM are to:
| • | Perform bi-directional 36 V DC to 12 V DC electrical energy conversion between the 36 V DC bus and the 12 V DC bus for system energy management. |
| • | Perform bi-directional DC/AC electrical energy conversion between the 36 V DC bus and the 3-phase asynchronous machine. |
| • | Provide 120 V A/C @ 60 Hz energy for on and off board electrical equipment. |
This SGCM will have 2 functions. The first will be monitoring, where the DC voltage is transformed into 3 phase A/C power to the starter generator interface. In this case, energy flows from the 36 V battery to Phase 1, Phase 2, and Phase 3. The second case will be generating, where the 3 phase AC power is used to charge the 36 V battery pack. In this case, energy flows from Phase 1, Phase 2, and Phase 3 to the 36 V battery. If the values of starter generator speed and starter generator torque are zero, then the starter generator control will be disabled and the starter generator inverter is not transferring or consuming any power.
Three-Phase A/C Current will be defined as the current value of Phase 1. The current will be bidirectional, with positive representing discharging the batteries and negative representing charging the batteries.
The following DTCs are for internal failures within the SGCM.
| • | P1AA9 value of phase U current is indicating an offset condition. |
| • | P1AAA value of phase W current is indicating an offset condition. |
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC P1AA9 Starter/Generator Phase U Current Sensor Performance
Conditions for Running the DTC
| • | The engine has been 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
The value of phase U current is indicating an offset condition.
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. |
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. |
Step | Action | Yes | No |
|---|---|---|---|
1 | Did you perform the Diagnostic System Check - Vehicle? | Go to Step 2 | |
2 |
Is DTC P1AA9 a current DTC? | Go to Step 3 | Go to Testing for Intermittent Conditions and Poor Connections |
3 | Replace the starter/generator control module (SGCM). Refer to Control Module References for replacement, setup, and programming. Did you complete the replacement? | Go to Step 4 | -- |
4 |
Does the DTC reset? | Go to Step 2 | System OK |
