High Voltage Battery Pack R&R

Complete removal and replacement of the high-voltage battery pack assembly on a 2023 Chevrolet Bolt EUV, including de-energization, coolant system disconnection, and structural mounting removal.

Warnings

Tools required

Parts

• High-voltage battery pack assembly × 1 — Use OEM specification
• Battery coolant (DEX-COOL) × 1 — ACDelco 10-5027
• Battery pack seal/gasket × 1 — Use OEM specification
• High-voltage interlock connector seal × 1 — Use OEM specification
• Coolant line O-rings × 4 — Use OEM specification

Fluids

• ACDelco DEX-COOL (Orange) — 10 qt

Preparation

1. Verify technician has completed manufacturer high-voltage safety training and certification
2. Place Class D fire extinguisher within immediate reach of work area
3. Establish 3-foot safety perimeter around vehicle with warning tape and signage
4. Ensure work area is dry, well-ventilated, and free of flammable materials
5. Verify vehicle is on level surface with wheels chocked and parking brake engaged
6. Remove 12V auxiliary battery negative cable and wait 2 minutes for module shutdown
7. Using scan tool, verify that no DTCs indicate battery damage or thermal events
8. Document battery state of charge (should be between 30-60% for safe handling)
9. Photograph all connector locations and routing for reassembly reference
10. Raise vehicle on lift to comfortable working height with all four wheels supported

Procedure

1. 1

   De-energize high-voltage system
   Locate the High Voltage Service Disconnect (HVSD) on the left rear of the battery pack, accessible from underneath vehicle. Remove the orange service disconnect cover by pressing release tabs. Wearing high-voltage gloves, rotate the service disconnect handle counterclockwise 1/4 turn and pull straight out to remove. Store disconnect in toolbox away from vehicle. Install safety lock-out tag. Wait minimum 10 minutes for capacitor discharge.
   ⚠️Do not proceed until 10-minute waiting period has elapsed. High-voltage capacitors require this time to safely discharge.
2. 2

   Verify de-energization
   Don high-voltage safety gloves. Using high-voltage multimeter, verify zero voltage across main battery terminals. Check voltage at DC/DC converter input terminals, onboard charger terminals, and motor inverter connections. All readings must be below 5V DC. If any voltage above 5V is detected, wait an additional 10 minutes and retest. Document all voltage readings.
   ⚠️If voltage does not drop below 5V after 20 minutes total wait time, do not proceed. System may have internal fault requiring specialized diagnosis.
3. 3

   Drain battery thermal management system
   Locate battery coolant drain valve on the battery thermal management system at the front of the pack. Place drain pan underneath. Open drain valve and allow coolant to drain completely (approximately 2.5 quarts will drain from battery circuit). Once drained, close valve. Locate and disconnect the two battery coolant lines at quick-connect fittings on the left side of the battery pack. Cap open lines to prevent contamination.
   ⚠Coolant may be warm even after waiting period. Verify system has cooled before opening drain valve.
4. 4

   Disconnect high-voltage connectors
   Wearing HV gloves, locate the orange high-voltage cables at the front-right of battery pack. Disconnect the High Voltage Interlock Loop (HVIL) connector by pressing release tab and pulling straight out. Remove the orange connector protective covers. Using appropriate socket, remove the high-voltage connector bolts from both positive and negative cables. Carefully separate connectors and position cables away from battery pack. Install protective caps on all exposed high-voltage terminals.
   Torque spec

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

   Disconnect low-voltage connections and sensors
   Disconnect the Battery Energy Control Module (BECM) connectors (3 connectors located on top-front of pack). Disconnect battery temperature sensor harnesses (2 connectors on top of pack). Disconnect current sensor connector at front of pack. Remove all wiring harness clips and route harnesses away from battery pack. Remove sensor mounting bolts where applicable and secure sensors to vehicle body.
   Torque spec

   Sensor Bolts11 Nm (8 lb-ft)
6. 6

   Remove underbody shields and covers
   Remove the front underbody shield by removing all cover screws. Remove the center underbody cover. Remove the rear underbody shield. These shields protect battery mounting hardware. Store shields in clean area. Remove the battery pack protective side covers (left and right) by removing all cover screws along perimeter.
   Torque spec

   Cover Screws11 Nm (8 lb-ft)
7. 7

   Support battery pack
   Position battery lift table or heavy-duty transmission jack under the center of the battery pack. Raise jack until it just contacts the battery pack bottom surface - do not apply lifting force yet. Ensure jack saddle is large enough to support entire pack (approximately 60 inches long by 42 inches wide). Use jack safety straps to secure battery to lift table to prevent shifting during removal. Have assistant verify pack is centered and stable on lift.
   ⚠️Battery pack weighs 960 lbs. Ensure lift equipment is rated for at least 1500 lbs capacity and is positioned on level floor.
8. 8

   Remove front mounting brackets and bolts
   Locate the front battery mounting brackets (left and right sides). Remove the front bracket bolts securing each bracket to the vehicle frame. There are 4 bolts per bracket. Once bracket bolts are removed, remove the brackets themselves. Inspect all bolts and brackets for damage or corrosion.
   Torque spec

   Bracket Bolts20 Nm (15 lb-ft)
9. 9

   Remove main battery mounting bolts
   Locate the primary battery mounting bolts - there are 8 total mounting bolts securing the battery pack to the vehicle chassis (4 front positions, 4 rear positions). Using appropriate torque wrench and socket, loosen all 8 mounting bolts in a cross-pattern sequence to prevent binding. Remove all mounting bolts completely and store in labeled container. Have assistant verify all mounting hardware is removed before attempting to lower pack.
   ⚠Battery pack will become free once all mounting bolts are removed. Ensure jack is properly supporting full weight before removing final bolts.
   Torque spec

   Mounting Bolts27 Nm (20 lb-ft)
10. 10

    Lower and remove battery pack
    With assistant monitoring clearances on both sides, very slowly lower the battery lift table. Monitor all sides for any remaining harness connections, coolant lines, or brackets that may have been missed. Lower pack approximately 6 inches and stop to perform final clearance check. If clear, continue lowering until pack can be rolled out from under vehicle. Carefully roll battery pack to designated storage area on level surface. If installing used/replacement pack, inspect all sealing surfaces and clean mounting points on vehicle.
    ⚠️Lower pack very slowly (1 inch per 5 seconds). Rushing can cause pack to shift on lift table or catch on unseen obstacles.
    ⚠Do not store battery pack on its side or at an angle. Keep pack level and supported across entire bottom surface.
11. 11

    Inspect and prepare for installation
    With old pack removed, inspect vehicle chassis mounting points for damage, corrosion, or debris. Clean all mounting surfaces with appropriate cleaner. Inspect all mounting bolt threads in chassis - clean or chase threads if necessary. Inspect the battery pack sealing gasket on replacement pack and verify it is properly seated. Inspect all coolant line quick-connects for damage. Position replacement battery pack on lift table in same orientation as removal, centered and secured with straps.
12. 12

    Install battery pack
    Carefully roll battery lift table with new pack under vehicle, centering it beneath the mounting points. Very slowly raise pack into position, monitoring clearances on all sides. Have assistant guide pack alignment while you control lift. Align all 8 mounting bolt holes. Raise pack until it contacts chassis mounting points with light pressure. Do not force - if pack does not seat easily, lower and verify alignment.
    ⚠Ensure battery gasket/seal remains properly positioned during installation. Misaligned seal will cause coolant leaks.
13. 13

    Install mounting bolts and brackets
    Install all 8 main mounting bolts finger-tight in a cross-pattern sequence. Once all bolts are started, torque bolts to specification in 3 stages using cross-pattern: first to 50% torque (13.5 Nm), then to 75% torque (20 Nm), finally to full torque (27 Nm). Reinstall front mounting brackets and torque bracket bolts to specification. Verify all fasteners are secure and pack is not shifting.
    Torque spec

    Mounting Bolts27 Nm (20 lb-ft)

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

    Reconnect sensors and low-voltage connections
    Reinstall battery temperature sensors and torque sensor bolts to specification. Reconnect all temperature sensor harnesses and verify positive engagement. Reconnect Battery Energy Control Module (BECM) connectors - all 3 connectors should click firmly into place. Reconnect current sensor connector. Reinstall all wiring harness clips in original positions per installation photos. Verify no harnesses are pinched or in contact with sharp edges.
    Torque spec

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

    Reconnect high-voltage system
    Remove protective caps from high-voltage terminals. Wearing HV gloves, position positive and negative cable connectors onto battery terminals. Install high-voltage connector bolts and torque to specification - these are critical safety connections. Install orange protective connector covers. Reconnect High Voltage Interlock Loop (HVIL) connector until it clicks securely. Verify HVIL connector lock is fully engaged.
    ⚠️High-voltage connector bolts are CRITICAL torque specifications. Under-torquing can cause arcing and fire; over-torquing can damage terminals. Use calibrated torque wrench.
    Torque spec

    Connector Bolts7 Nm (5 lb-ft)
16. 16

    Reconnect battery thermal management system
    Install new O-rings on battery coolant line quick-connects. Connect both coolant lines to battery pack fittings - press firmly until you hear and feel positive click engagement. Pull on each line to verify secure connection. If equipped with threaded coolant fittings instead of quick-connects, torque coolant line fittings to specification.
    Torque spec

    Coolant Line Fittings15 Nm (11 lb-ft)
17. 17

    Reinstall covers and shields
    Install battery pack side covers (left and right) and torque all cover screws to specification around perimeter. Install rear underbody shield, center underbody cover, and front underbody shield in that order. Torque all cover screws to specification. Verify all shields are fully seated and no gaps exist where debris could enter.
    Torque spec

    Cover Screws11 Nm (8 lb-ft)
18. 18

    Refill battery thermal management system
    Fill battery thermal management system with fresh ACDelco DEX-COOL coolant per vehicle specifications. Use vacuum fill procedure if available, or fill through reservoir and run bleeding procedure. Start with approximately 2.5 quarts for battery circuit. Monitor coolant level and add as needed. Check for leaks at all coolant connections on battery pack during filling process.
19. 19

    Energize system and perform initial checks
    Reconnect 12V auxiliary battery negative cable. Remove lock-out tag from HVSD storage location. Wearing HV gloves, install High Voltage Service Disconnect by inserting fully and rotating clockwise 1/4 turn until it locks. Install orange HVSD cover. Using scan tool, command battery system energization and monitor for any fault codes. Check for proper voltage readings at main battery terminals (should show approximately 350-400V depending on state of charge).
    ⚠️System is now energized. High voltage is present. Maintain awareness and continue using appropriate PPE.
20. 20

    Final verification and programming
    Using GM MDI scan tool, perform battery pack registration and configuration procedures per manufacturer service information. Clear any installation-related DTCs. Verify Battery Energy Control Module recognizes new pack and all parameters are within normal range. Run thermal management system self-test. Check battery state of health and state of charge readings. Verify all battery temperature sensors are reading normally and within 5°C of each other.

Reassembly

1. Lower vehicle from lift and perform final walk-around inspection of all underbody panels
2. Test drive vehicle in safe area to verify normal operation - monitor for any warning lights or unusual behavior
3. After test drive, raise vehicle and re-inspect all coolant connections for leaks
4. Re-torque all critical fasteners after test drive as thermal cycling may cause settling
5. Using scan tool, verify no new DTCs have set during test drive
6. Print battery system health report from scan tool for customer records

Verification

• Scan tool shows no high-voltage system DTCs and battery pack is recognized with correct parameters
• High-voltage system voltage reading is between 350-400V DC (varies with state of charge)
• All battery temperature sensors reading within normal range (typically 15-35°C ambient) and within 5°C of each other
• Battery thermal management system shows proper coolant flow and no leaks visible
• High Voltage Interlock Loop (HVIL) circuit shows closed/normal status on scan tool
• All underbody shields and covers are properly installed with no missing fasteners
• Vehicle operates normally in all drive modes with full power available
• Battery state of health (SOH) reading is appropriate for replacement pack (typically 95-100% for new pack)
• Coolant level in reservoir is at proper level and system shows no air in circuit
• Test drive confirms normal regenerative braking, acceleration, and no warning lights

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