P1AAC

DTC P1AAC

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:
- 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 battery 36-volt to Phase 1, Phase 2, Phase 3. The second case will be generating, where the three phase AC power is used to charge the 36 V battery pack. In this case, energy flows from Phase 1, Phase 2, Phase 3 to battery 36-volt. 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.
- P1AAB phase U current = 0 amps when the Starter Generator torque is being commanded.
- P1AAC the sum of phases U and W current = 0 amps when the Starter Generator torque is being commanded.
- P1AAD phase W current = 0 amps when the Starter Generator torque is being commanded.
- P1AAE an unbalanced operation condition is present during steady state operation.

DTC DESCRIPTOR
This diagnostic procedure supports the following DTC:
DTC P1AAC Starter/Generator Phase V Circuit

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.

CONDITIONS FOR SETTING THE DTC
- P1AAB Phase U Open/Short Fault
- P1AAC Phase V Open/Short Fault
- P1AAD Phase W Open/Short Fault
- P1AAE Phase Correlation Fault

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.

TEST

Steps 1-8:

Step 9: