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 serial data. The HPCM is the host controller for diagnostic trouble code (DTC) information.

The hybrid battery assembly consists of 40 individual batteries. Each battery is rated at 7.2 V. A pair of batteries is rated at 14.4 V. The batteries are connected together in a series circuit. The BECM monitors the hybrid battery voltage on every two batteries for a total of 20 locations, across the battery assembly. The BECM monitors and compares these 20 voltage measurements, if the BECM detects a voltage difference greater than a calibrated value on any two consecutive hybrid battery voltage measurements this DTC will set.

The BECM detects greater than a 1.5 V difference between any two hybrid battery voltage measurements for 3 seconds. However, if any DTCs P0B3C-P0B9D are set, the corresponding battery voltage measurement is ignored by this DTC.

Schematic Reference

Hybrid Energy Storage Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Drive Motor Battery System Description

Electrical Information Reference

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Control Module References for scan tool information

Special Tools

Ignition ON, observe the scan tool Hybrid Battery 1-20 parameters. Each reading should be between 13-19 Volts, and all readings should be within 1.5 Volts of each other.

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.

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.
2. Remove the drive motor generator battery case upper cover. Refer to Drive Motor Battery Case Upper Cover, Front Cover, and Right Side Cover Replacement.
3. Disconnect the X4 harness connector at the BECM.
4. Connect the EL-48571 high voltage battery pin out box to the X4 harness connector.
5. Install the high voltage manual disconnect lever.
6. Test for 13-19 V across all 20 battery voltage reference circuits and that they are within 1.5 V of each other.

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

7. If all circuits test normal, replace the drive motor battery control module assembly.

Perform the Diagnostic Repair Verification after completing the repair.