High Voltage Battery Module R&R

Remove and replace a high-voltage battery module from the 2023 Chevrolet Bolt EUV 65 kWh battery pack, including isolation, disassembly, module extraction, and system verification.

Warnings

Tools required

Parts

• High-voltage battery module assembly × 1 — Use OEM specification - module specific to position
• Battery module thermal interface pad × 1 — Use OEM specification
• High-voltage connector seals × 2 — Use OEM specification
• Coolant hose O-rings × 4 — Use OEM specification
• Battery pack cover gasket/seal × 1 — Use OEM specification if damaged

Fluids

• ACDelco DEX-COOL (Orange) — 2 qt

Preparation

1. Park vehicle on level surface in well-ventilated area away from ignition sources
2. Verify state of charge is below 30% using instrument cluster display (charge down if necessary for safety)
3. Allow vehicle to sit unpowered for minimum 2 hours to cool high-voltage system and coolant
4. Ensure high-voltage insulated gloves are inspected and rated for minimum 1000V Class 0 service
5. Connect GDS2 scan tool and perform 'High-Voltage System Disable' procedure - save all diagnostic data
6. Disconnect 12-volt auxiliary battery negative terminal and wait 2 minutes for system discharge
7. Raise vehicle on lift to comfortable working height with all four wheels supported
8. Remove both front wheels to access underbody components
9. Remove lower belly pan and battery pack protective covers
10. Place coolant drain pan under battery pack coolant connections

Procedure

1. 1

   Isolate high-voltage system
   Locate the high-voltage service disconnect (orange connector) at front of battery pack near driver side. Wearing insulated gloves, unlock the service disconnect by rotating counterclockwise 1/4 turn, then pull firmly straight up to remove. Store disconnect in secure location away from vehicle. Install insulated safety cover over exposed terminals. Wait minimum 15 minutes for capacitor discharge.
   ⚠️Do not proceed until 15-minute capacitor discharge period is complete. Verify with multimeter before touching any high-voltage components.
2. 2

   Verify high-voltage isolation
   Using CAT III rated multimeter, verify zero voltage between high-voltage bus bars at service disconnect location. Test between positive-to-negative and both positive-to-chassis and negative-to-chassis. All readings must show 0V DC (below 3V). Document readings. If voltage present, do not proceed - contact GM technical support.
   ⚠️If any voltage above 3V DC is detected, the system has not properly discharged. Do not proceed with repairs.
3. 3

   Drain battery cooling system
   Locate battery coolant drain valve on driver side of battery pack (near rear corner). Attach drain hose to valve and route to drain pan. Open drain valve by turning counterclockwise 2 full turns. Allow coolant to drain completely (approximately 1.5-2 quarts). Close drain valve when complete. Disconnect battery coolant inlet and outlet lines at pack connections using line disconnect tool.
   Torque spec

   Coolant Line Fittings15 Nm (11 lb-ft)
4. 4

   Disconnect electrical connections
   Identify and photograph all electrical connectors on battery pack upper surface for reassembly reference. Disconnect battery management system connectors (4 total - gray connectors near center of pack). Disconnect cell voltage sensing harnesses (orange tab connectors along module rows). Disconnect temperature sensor connectors (black 2-pin connectors). Remove connector support brackets using appropriate socket.
   Torque spec

   Connector Bolts7 Nm (5 lb-ft)

   Bracket Bolts20 Nm (15 lb-ft)
5. 5

   Remove battery pack upper cover
   Remove all upper cover screws in sequence working from center outward (approximately 24 screws total around perimeter and center beam). Carefully lift upper cover assembly straight up, being mindful of any trapped wire harnesses. Set cover on clean protective surface with gasket side facing up. Inspect gasket seal for damage.
   ⚠Cover is aluminum and can be damaged if bent. Use two-person lift technique for removal.
   Torque spec

   Cover Screws11 Nm (8 lb-ft)
6. 6

   Document and identify target module
   Battery pack contains 10 modules arranged in two rows of 5. Identify the specific module requiring replacement using scan tool diagnostic data or visual inspection. Document module position (Row A or B, Position 1-5 from front). Photograph module serial number and all adjacent connections. Verify replacement module matches position requirements.
   ℹ️Module positions are not interchangeable. Replacement module must match original position specification.
7. 7

   Disconnect module high-voltage connections
   Wearing insulated gloves and using insulated tools, locate the high-voltage busbars connecting target module to adjacent modules (front and rear connections). Remove high-voltage connector bolts securing busbars to module terminals. Carefully lift busbars away from module terminals and secure with non-conductive ties to prevent contact. Remove any inter-module support brackets.
   ⚠️Even with system isolated, treat all orange components as energized. Individual modules can retain voltage between cells.
   Torque spec

   Connector Bolts7 Nm (5 lb-ft)
8. 8

   Disconnect module sensors and cooling
   Disconnect temperature sensors mounted on target module (typically 2 sensors per module - front and rear). Remove sensor mounting hardware. If module has dedicated coolant connections, disconnect coolant quick-connects by pressing release tabs and pulling straight out. Cap any open coolant ports immediately to prevent contamination.
   Torque spec

   Sensor Bolts11 Nm (8 lb-ft)
9. 9

   Remove module mounting fasteners
   Remove battery module mounting bolts securing module to pack tray (typically 4-6 bolts per module around perimeter). Follow removal sequence from service manual if specified (generally work from center outward). Keep all mounting hardware organized by position for reassembly. Check for any additional brackets or restraints securing module.
   Torque spec

   Battery Module Bolts25 Nm (18 lb-ft)
10. 10

    Extract battery module
    Using proper two-handed lifting technique or module extraction tool, carefully lift battery module straight up out of pack tray. Module weighs approximately 40 lbs - do not drop or impact. Place module on insulated, non-conductive surface. Inspect pack tray for any debris, coolant leaks, or damage. Clean mounting surface with isopropyl alcohol and lint-free cloth.
    ⚠️Do not place removed module on conductive surface or near metal objects that could short terminals. Keep module at least 12 inches from any metal.
11. 11

    Prepare new module installation
    Unpack replacement module and verify serial number matches position requirements. Inspect new module for any shipping damage. Apply new thermal interface pad to bottom of module if required (verify service manual for specific position). Ensure all terminal contacts are clean and free of corrosion. Install new high-voltage connector seals on module terminals.
    ⚠New modules may arrive at different state of charge than pack. This is normal and will be balanced during initialization.
12. 12

    Install replacement module
    Carefully lower replacement module into pack tray, ensuring proper orientation (positive/negative terminal alignment with busbars). Guide module straight down into position, seating fully on thermal interface pad. Verify module is flush with adjacent modules and properly seated in tray guides. Install module mounting bolts hand-tight initially, then torque in specified sequence (typically center bolts first, then corners in star pattern).
    ⚠Do not force module into position. If module does not seat easily, remove and check for obstructions or misalignment.
    Torque spec

    Battery Module Bolts25 Nm (18 lb-ft)
13. 13

    Reconnect module high-voltage connections
    Position high-voltage busbars onto module terminals, ensuring proper alignment and full contact. Install high-voltage connector bolts and torque to specification using calibrated torque wrench. Apply dielectric grease to exposed terminals as specified. Install inter-module support brackets if present. Perform visual inspection of all connections for proper seating.
    ⚠️High-voltage connections are CRITICAL. Under-torqued connections can cause arcing and fire. Over-torqued connections can damage terminals. Use calibrated torque wrench.
    Torque spec

    Connector Bolts7 Nm (5 lb-ft)

    Bracket Bolts20 Nm (15 lb-ft)
14. 14

    Reconnect sensors and cooling connections
    Install temperature sensors to module using new mounting hardware if required. Torque sensor bolts to specification. Reconnect temperature sensor electrical connectors, ensuring positive lock engagement. If module has coolant connections, reconnect coolant lines and verify quick-connect clips are fully engaged. Replace any damaged O-rings.
    Torque spec

    Sensor Bolts11 Nm (8 lb-ft)
15. 15

    Reinstall battery pack cover and connections
    Inspect upper cover gasket and replace if damaged. Position upper cover onto battery pack, carefully aligning all mounting holes. Install cover screws and torque in sequence from center outward to ensure even gasket compression. Reconnect all battery management system connectors, cell voltage sensing harnesses, and temperature sensor connectors. Install connector support brackets. Reconnect battery coolant inlet and outlet lines, torquing fittings to specification.
    Torque spec

    Cover Screws11 Nm (8 lb-ft)

    Coolant Line Fittings15 Nm (11 lb-ft)

    Connector Bolts7 Nm (5 lb-ft)

    Bracket Bolts20 Nm (15 lb-ft)
16. 16

    Refill cooling system
    Close battery coolant drain valve and verify tight. Using DEX-COOL orange coolant, refill battery cooling system through fill port until coolant is visible at level indicator. Fill slowly to prevent air pockets (approximately 2 quarts). With scan tool, activate battery coolant pump purge function to remove air from system. Top off coolant as needed. Verify no leaks at all coolant connections.
    ⚠Use only GM-approved DEX-COOL orange coolant. Other coolants can damage battery cooling system components.
17. 17

    Perform system initialization
    Reconnect 12-volt auxiliary battery negative terminal. With scan tool, perform 'High-Voltage Battery Module Replacement' procedure from service programming menu. This will register new module serial number to BCM and initiate battery management system relearn. Follow all on-screen prompts. Process takes approximately 15-20 minutes. Do not interrupt.
    ⚠Module registration must be completed before energizing high-voltage system or vehicle will set fault codes and disable propulsion.
18. 18

    Reinstall high-voltage service disconnect
    Remove safety cover from service disconnect receptacle. Wearing insulated gloves, align service disconnect connector and press firmly straight down until seated. Rotate clockwise 1/4 turn to lock in place. Verify lock indicator is in locked position. Using scan tool, clear any stored high-voltage system codes. Enable high-voltage system through scan tool 'HV Enable' function.
    ⚠️High-voltage system will be energized after this step. Maintain proper safety protocols around orange components.

Reassembly

1. Reinstall battery pack protective covers and lower belly pan using appropriate fasteners
2. Reinstall both front wheels and torque lug nuts to 140 Nm (103 lb-ft) in star pattern
3. Lower vehicle from lift to ground level
4. Using scan tool, verify no diagnostic trouble codes present in battery management system
5. Verify battery pack cooling system pressure holds and no leaks present after pump activation
6. Allow vehicle to sit for 1 hour, then recheck coolant level and top off if necessary

Verification

• Connect scan tool and verify battery module replacement registration successful - new module serial number should appear in BCM data
• Using scan tool, monitor individual cell voltages - all cells should be within 0.1V of each other initially (balancing occurs over subsequent charge cycles)
• Verify battery pack coolant temperature sensor readings are reasonable (within 5°C of ambient)
• Perform high-voltage isolation test - resistance between HV+ and chassis should exceed 500 kΩ, HV- and chassis should exceed 500 kΩ
• If available, use thermal camera to inspect battery pack during first charge cycle - all modules should show similar temperature profiles (within 5°C)
• Start vehicle and verify READY indicator illuminates with no warning messages on instrument cluster
• Test drive vehicle and verify normal propulsion system operation - no power limitations or fault messages
• After first 50 miles of operation, recheck for diagnostic codes and verify cell voltage balance is improving (variance should decrease below 0.05V)
• Verify battery state of charge displays correctly and matches expected values during charging
• Check for any coolant leaks around battery pack connections after vehicle reaches operating temperature

Related trouble codes on this vehicle

Codes that commonly send this job to the bay — tap one for symptoms, causes, and diagnostic steps.

Chasing one of these codes and not sure which part is guilty? Ask a master mechanic about YOUR car →

More procedures for this vehicle