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

The BECM has several methods of monitoring the total voltage values of the hybrid batteries. The BECM monitors the calculated battery voltage and the terminal voltage. The calculated voltage represents the sum of the voltages from the 20 individual battery measurements, and the terminal voltage represents the total DC bus voltage as measured on the output side of the high voltage contactor relays. The BECM compares these two voltage readings and looks for a difference. The BECM also monitors the terminal voltage for both over voltage and under voltage conditions.

P0ABB

The BECM detects a 50 volt difference between the hybrid battery pack calculated voltage and the hybrid battery terminal voltage for 7 out of 8 seconds.

P0ABC

The BECM detects the terminal voltage is less than 50 volts for 3 out of 4 seconds.

P0ABD

The BECM detects the terminal voltage is greater than 430 volts for 3 out of 4 seconds.

DTCs P0ABB, P0ABC, and P0ABD are Type A DTCs.

Schematic Reference

Hybrid Energy Storage Schematics

Connector End View Reference

Component Connector End Views

Electrical Information Reference

Scan Tool Reference

Control Module References for scan tool information

Special Tools

1. Ignition ON, engine OFF, verify that the hybrid battery pack calculated voltage parameter and the hybrid battery terminal voltage parameter are greater than 169 volts and less than 408 volts.
2. Ignition ON, engine OFF, verify that the hybrid battery pack calculated voltage and the hybrid battery pack terminal voltages are within 50 volts of each other.
3. Operate the vehicle within the Conditions for Running the DTC to verify the DTC does not reset. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.

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.

P0ABB

1. Verify if DTC P0ABC is set.

⇒	If DTC P0ABC is set, diagnose that first.

2. Ignition OFF, disable the high voltage at the drive motor generator battery. Refer to High Voltage Disabling .
3. Remove the drive motor generator battery case upper cover, front cover and right side cover. Refer to Drive Motor Battery Case Upper Cover, Front Cover, and Right Side Cover Replacement .
4. Install the high voltage manual disconnect lever.
5. Ignition OFF, Using a DMM, measure and record the pack voltage by measuring between terminals HV+ at the HV positive contactor relay and HV- at the HV negative contactor relay.
6. Connect the 12 volt battery.
7. Ignition ON, observe the hybrid battery pack calculated voltage parameter using a scan tool. Compare the calculated voltage value to the voltage value measured and recorded with the DMM. The voltage values should be within 20 volts.

⇒	If within the specified range, test the 300 volt reference circuits for an open/high resistance between the BECM X5 and HV terminals, If all circuits test normal, replace the drive motor generator battery control module.

8. Disconnect the X4 harness connector at the BECM.
9. Connect the EL-48571 to the X4 harness connector.
10. Test for 13-19 volts across all 20 battery voltage reference circuits.

⇒	If not within the specified range, replace the drive motor battery assembly.

⇒	If all circuits test normal, replaced the drive motor generator battery control module.

P0ABC

1. Verify if DTCs P0C77 or P1A20 are set.

⇒	If DTCs P0C77 or P1A20 are set, diagnose them first.

2. Ignition ON, observe the BECM hybrid battery pack calculated voltage parameter using a scan tool.

⇒	If the voltage is below 194 volts, replace the drive motor generator battery.

3. Ignition OFF, disable the high voltage at the drive motor generator battery. Refer to High Voltage Disabling .
4. Remove the drive motor generator battery case upper cover, front cover and right side cover. Refer to Drive Motor Battery Case Upper Cover, Front Cover, and Right Side Cover Replacement .
5. Connect the 12 volt battery.
6. Ignition ON, engine OFF, connect a DMM between HV+ and HV- terminals of the HV positive contactor relay. With a scan tool, command the HV positive relay CLOSED. Verify less than 0.5 ohms of resistance.

⇒	If the resistance is greater than the specified value, replace the HV Positive contactor relay.

7. Ignition ON, engine OFF, connect a DMM between HV+ and HV- terminals of the HV negative relay. With a scan tool, command the HV negative relay CLOSED. Verify less than 0.5 ohms of resistance.

⇒	If the resistance is greater than the specified value, replace the HV negative relay.

8. Test for an open or high resistance in the HV DC cables between the HV positive and negative contactor relays and the HV hybrid battery terminals.

⇒	Replace any damaged or open components as required.

9. Test for an open or high resistance in the HV DC cables between the HV positive and negative contactor relays and the HV terminal block.

⇒	Replace any damaged or open components as required.

10. Test for an open or high resistance in the HV positive and negative sensor harness between the 300V terminal block and the BECM X5 connector.

⇒	Replace any damaged or open components as required.

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

P0ABD

Ignition ON, observe the hybrid battery pack calculated voltage parameter using a scan tool. You should observe less than 430 volts.

Perform the Diagnostic Repair Verification after completing the repair.