Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Theory Of Operation
The Battery Pack Control Module (BPCM) is contained within the High Voltage (HV) Battery Pack. The BPCM provides battery management and system functionality in conjunction with Cell Supervisory Circuit Modules that monitor and balance the battery cells through Cell Supervision Circuits as well as the monitoring of related external support systems. The Cell supervision Circuits (CSC) are hard wired between the Battery Modules and the Cell Supervisory Circuit Modules. The BPCM is the High Voltage Interlock (HVIL) power source and communicates with the vehicle via CAN-C bus. The main functions of the BPCM are high-voltage bus and pre-charge contactor control, battery pack current, voltage and temperature sensing, CAN communication, fault detection and reporting. The BPCM monitors and reports cell temperatures to the Electric Vehicle Control Unit (EVCU) for thermal management proposes to ensure the optimal life of the battery. Diagnosing any DTC related to the BPCM should start with verifying that all external High Voltage related DTCs, fuses, wiring and connections critical to proper system operations have been repaired, and wiring and connections are securely installed and connected. Internal High Voltage Battery fuses cannot be serviced at this time.
| 1 - Battery Pack Control Module (BPCM) |
On vehicles equipped with the high voltage system, you must thoroughly read and follow all High Voltage Safety procedures. In addition, before performing any diagnostic or service procedure near a high voltage component, you must perform the High Voltage Power Down. Failure to follow these instructions may result in possible serious or fatal injury.
Always power down the High Voltage System before performing diagnostic tests or repairs to the High Voltage system. Refer to VEHICLE HIGH VOLTAGE POWER DOWN .
Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. Refer to PRE-DIAGNOSTIC TROUBLESHOOTING PROCEDURE .
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.