P0B7E – Low voltage in hybrid/electric vehicle battery circuit 14

Code P0B7E – Causes, Symptoms, and Repairs

Possible Causes

• Defective hybrid/electric vehicle battery
• Faulty hybrid/electric vehicle battery interface control module

Possible Symptoms

• Check engine light on (or service engine soon warning light)

Meaning of Code P0B7E

The hybrid/electric vehicle battery contains 288 cells, divided into 96 groups of three cells welded together in parallel. These cell groups are electrically connected in series, with each group having a voltage of 3.7V, resulting in a nominal system voltage of 355V DC.

The battery cells are divided into three distinct sections:

1. Section 1: Located at the front, near the hood, it contains batteries 67 to 96 (90 cells / 30 cell groups).
2. Section 2: Located behind section 1, it contains batteries 43 to 66 (72 cells / 24 cell groups).
3. Section 3: Contains batteries 1 to 42 (126 cells / 42 cell groups).

These battery sections are individually repairable components.

The battery energy control module monitors the voltage of the 96 cell groups via four hybrid/EV battery interface control modules. Each cell group is connected to a voltage sensing circuit terminated at a connector located on the top surface of the battery section. An auxiliary battery wiring harness connects this connector to a hybrid/EV battery interface control module.

• Each battery section is supervised by one or more hybrid/EV battery interface control modules.
• Voltage information is transmitted to the battery energy control module, which detects anomalies and communicates diagnostic codes to the hybrid/EV powertrain control module 2.
• The latter is responsible for displaying and storing error codes.

Inspection and Repair Procedures

1. Visual Inspection
   • Inspect the wiring harness and associated connectors.
   • Look for broken, bent, pushed out, or corroded connector pins.
2. Electronic Diagnosis
   • Use an OBD-II diagnostic tool to check for the presence of code P0B7E and other related codes.
   • Clear the error codes and test the vehicle to see if the code returns.
3. Module and Sensor Verification
   • Test the voltage of the cell groups with a multimeter to identify any faulty battery section.
   • Check the integrity of the hybrid/EV battery interface control modules.
4. Replacement of Faulty Components
   • If the battery is defective, consider replacing it.
   • If the hybrid/EV battery interface control module is at fault, replace it.

Conclusion

A P0B7E code indicates a potential issue with the hybrid/electric battery or its control module. Prompt action is recommended to avoid damaging other vehicle components. By following the verification and diagnostic procedures, it is possible to determine the source of the problem and correct it effectively.