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P1A0C




DTC P1A0C or P1A0D

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis Strategy Based Diagnosis for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions Diagnostic Procedure Instructionsprovides an overview of each diagnostic category.

DTC Descriptors
DTC P1A0C
- Battery Energy Control Module System Voltage Low

DTC P1A0D
- Battery Energy Control Module System Voltage High

Circuit/System Description

The drive motor generator battery control module is also referred to as the battery energy control module (BECM). The drive motor generator battery control module will diagnose its own systems and determine when a fault condition is present. Diagnostics and system status is communicated from the drive motor generator battery control module to the hybrid powertrain control module (HPCM) through serial data. The hybrid powertrain control module is the host controller for diagnostic trouble code (DTC) information. The drive motor generator battery control module continuously monitors the system voltage on the ignition 1 voltage circuit.

Conditions for Running the DTC

* The vehicle power mode is RUN.
* DTC P0A1F is not set.

Conditions for Setting the DTC

P1A0C

The drive motor generator battery control module detects the ignition voltage is less than 9 V for 3 seconds.

P1A0D

The drive motor generator battery control module detects the ignition voltage is greater than 16 V for 3 seconds.

Action Taken When the DTC Sets

P1A0C
* DTCs P1A0C and P1A0D are Type C DTCs.
* The drive motor generator battery control module commands the battery vent fan to High.

P1A0D
* DTCs P1A0C and P1A0D are Type C DTCs.
* The drive motor generator battery control module commands the battery vent fan to High.
* After 8 minutes of ignition voltage over 16 V, the high voltage contactor coils will become hot and the drive motor generator battery control module will open the contactors. The drive motor generator battery control module will not close the high voltage contactors for 30 minutes to allow high voltage contactors to cool.

Conditions for Clearing the DTC

* DTCs P1A0C and P1A0D are Type C DTCs.
* The control module ignition voltage is between 9-16 V.

Diagnostic Aids

Observe the driver information center (DIC) messaging that would indicate the charging system requires service.

Inspect for the following conditions:

* Loose or poor connections at the hybrid drive motor battery X350 18-way connector.
* Loose or poor connections at the 12 V negative battery cable G102.
* Verify that the 12 V battery and charging system is within normal operating range and if a battery charger was connected to the vehicle.
* Loose or damaged battery terminals.
* Loose or corroded connections at the accessory dc power control module (APM).

Reference Information
Schematic Reference

Hybrid Energy Storage Schematics [1][2]Electrical Diagrams
Connector End View Reference

Component Connector End Views Connector End Views By Name
Electrical Information Reference

* Circuit Testing Circuit Testing
* Connector Repairs Connector Repairs
* Testing for Intermittent Conditions and Poor Connections Testing for Intermittent Conditions and Poor Connections
* Wiring Repairs Wiring Repairs

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions Powertrain Diagnostic Trouble Code (DTC) Type Definitions
Scan Tool Reference

Control Module References Programming and Relearningfor scan tool information
Special Tools

EL-48900 HEV Safety Kit

Circuit/System Verification

1. Verify that DTC P0A8D or P0A8E is not set.

• If any of the DTCs are set. Refer to Diagnostic Trouble Code (DTC) List - Vehicle Diagnostic Trouble Code (DTC) List - Vehicle.

2. Ignition OFF, measure and record the battery voltage at the battery terminals. The battery voltage should be between 12.4 and 12.8 V within a few minutes of turning the ignition OFF.

• If not within the specified range, refer to Battery Inspection/Test Battery Inspection/Test.

3. Engine running, accessories OFF, measure and record the battery voltage at the battery terminals. The voltage should be at least 1 V greater than the voltage measured in step 1 but less than 15.5 V.

• If not within the specified range, refer to Charging System Test Charging System Test.

4. Observe the scan tool drive motor generator battery control module, Control Module Voltage parameter. The reading should be within 1 V of the battery voltage.

Circuit/System Testing

Danger: Always perform the High Voltage Disabling procedure prior to servicing any High Voltage component or connection. Personal Protection Equipment (PPE) and proper procedures must be followed.


The High Voltage Disabling procedure will perform the following tasks:


* Identify how to disable high voltage.

* Identify how to test for the presence of high voltage.

* Identify condition under which high voltage is always present and personal protection equipment (PPE) and proper procedures must be followed.


Before working on any high voltage system, be sure to wear the following Personal Protection Equipment:


* Safety glasses with appropriate side shields when within 15.24 meters (50 feet) of the vehicle, either indoors or outdoors.

* Certified and up-to-date Class "0" Insulation gloves rated at 1000V with leather protectors.


- Visually and functionally inspect the gloves before use.

- Wear the Insulation gloves at all times when working with the high voltage battery assembly, whether the system is energized or not.


Failure to follow the procedures exactly as written may result in serious injury or death.


1. Ignition OFF, disable the high voltage at the drive motor generator battery. Refer to High Voltage Disabling High Voltage Disabling.
2. Ignition OFF, disconnect the X1 harness connectors at the drive motor generator battery control module.
3. Ignition OFF, scan tool disconnected, open and close the driver door and wait 1 minute. Test for less than 5 ohm between the ground circuit terminal 11 and ground.

• If greater than the specified range, test the ground circuit for an open/high resistance.

4. Verify that a test lamp illuminates between the B+ circuit terminal 1 and ground.

• If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance.

5. Ignition ON, verify that a test lamp illuminates between the ignition circuit terminal 12 and ground.

• If the test lamp does not illuminate, test the ignition circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the serial data gateway module.

6. If all circuits test normal, replace the drive motor generator battery control module.

Repair Instructions

Perform the Diagnostic Repair Verification Verification Tests after completing the diagnostic procedure.

Control Module References Programming and Relearningfor drive motor generator battery control module or serial data gateway module replacement, setup, and programming

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