P1A99
DTC P1A99
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 volts DC and 14 volts DC buses via the APM, bi-directional 42 volts DC to 14 volts DC converter. All APM functions shall only be run when in the enable mode. APM current shall be defined as the current flowing through the outputs. The current shall be bi-directional, with negative current representing 14-42 volts direction, and positive current representing the 42-14 volts direction.
The starter generator control module (SGCM) controls 2 functions in these DTCs. DC voltage is transformed into three phase AC power to the electric machine interface. In this case, energy flows from 36 volt to phase1, phase2 and phase3. The second case shall be generating, where the three phase AC power is used to charge the 36 volt battery pack. In this case, energy flows from phase1, phase2 and phase3 to 36 volts.
The following DTCs are for internal failures within the SGCM.
- P1A97 SGCM 42 volts bus voltage is less than 6 volts.
- P1A98 SGCM 42 volts bus voltage is greater than 55 volts.
- P1A99 SGCM 42 volts bus current is less than -600 amps.
- P1A9A SGCM 42 volts bus current is greater than 600 amps.
DTC DESCRIPTORS
This diagnostic procedure supports the following DTCs:
- DTC P1A97 Starter/Generator Control Module Hybrid Battery Voltage Sensor Circuit Low Voltage
- DTC P1A98 Starter/Generator Control Module Hybrid Battery Voltage Sensor Circuit High Voltage
- DTC P1A99 Starter/Generator Control Module Hybrid Battery Current Sensor Circuit Low Current
- DTC P1A9A Starter/Generator Control Module Hybrid Battery Current Sensor Circuit Low Current
CONDITIONS FOR RUNNING THE DTC
- Engine running for more than 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
- P1A97 SGCM 42 volts bus voltage is less than 6 volts.
- P1A98 SGCM 42 volts bus voltage is greater than 55 volts.
- P1A99 SGCM 42 volts bus current is less than -600 amps.
- P1A9A SGCM 42 volts bus current is greater than 600 amps.
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 PCM records the operating conditions at the time the diagnostic fails. The PCM stores this information in the Failure Records.
- 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.
TEST
