Battery Thermal Management Module

This procedure covers the removal and replacement of the Battery Thermal Management Module on a 2023 Chevrolet Bolt EUV, which controls cooling and heating of the high-voltage battery pack.

Warnings

Tools required

Parts

• Battery Thermal Management Module × 1 — Use OEM specification
• Coolant line O-rings × 4 — Use OEM specification
• Thermal interface pad (if equipped) × 1 — Use OEM specification
• High-voltage connector seals × 2 — Use OEM specification

Fluids

• ACDelco DEX-COOL (Orange) — 2 qt

Preparation

1. Place vehicle on level surface and set parking brake. Place safety cones around work area.
2. Ensure vehicle has been shut down for minimum 2 hours to allow coolant system to cool and depressurize.
3. Disconnect 12-volt battery negative terminal and wait minimum 5 minutes before proceeding.
4. Remove rear seat bottom cushion to access high-voltage service disconnect.
5. Using scan tool, verify battery state of charge is below 95% (optimal range 30-60% for servicing).
6. Document any diagnostic trouble codes present before beginning work.
7. Put on high-voltage safety gloves and ensure all required safety equipment is available.

Procedure

1. 1

   De-energize high-voltage system
   Locate the high-voltage service disconnect under the rear seat. Remove the orange connector cover. Rotate the service disconnect handle counterclockwise and pull straight out to remove. Store in a secure location away from vehicle. Install the service disconnect lock-out device to prevent reinstallation. Wait an additional 5 minutes after removal.
   ⚠️Verify the service disconnect is completely removed and secured away from the vehicle before proceeding to next steps.
2. 2

   Verify zero voltage
   Using a properly calibrated high-voltage multimeter, verify zero voltage (less than 3V DC) at the high-voltage bus bars near the service disconnect location. Check voltage between positive and negative terminals, positive to chassis ground, and negative to chassis ground. Document all readings. If voltage is present, do not proceed until system is fully discharged.
   ⚠️If any voltage above 3V DC is detected, wait an additional 10 minutes and retest. Do not proceed if voltage remains present.
3. 3

   Drain battery coolant system
   Locate the battery coolant drain plug on the underside of the vehicle near the battery pack front edge. Position drain pan underneath. Slowly open the drain valve and allow coolant to drain completely. On 2023 Bolt EUV, the battery thermal system holds approximately 1.5-2 quarts. Once drained, close drain valve.
   ⚠Coolant may still be warm. Open drain valve slowly to prevent splashing.
4. 4

   Remove underbody shield
   Remove the plastic underbody shield covering the battery pack area. Remove the fasteners (typically 12-15 push-pins and screws) and carefully lower the shield. Inspect shield for damage and set aside for reinstallation.
   Torque spec

   Cover Screws11 Nm (8 lb-ft)
5. 5

   Disconnect coolant lines
   Locate the coolant line connections to the thermal management module on the underside of the battery pack. Using appropriate line disconnect tools, carefully disconnect the inlet and outlet coolant lines. Have shop towels ready to catch residual coolant. Cap the open lines immediately to prevent contamination. Remove and inspect O-rings; replace with new O-rings during reassembly.
   ⚠Coolant lines may still contain pressurized fluid. Relieve pressure slowly before fully disconnecting.
   Torque spec

   Coolant Line Fittings15 Nm (11 lb-ft)
6. 6

   Disconnect electrical connectors
   Locate the low-voltage electrical connectors on the thermal management module (typically 2-3 connectors for sensors and control signals). Press the connector lock tabs and carefully pull connectors straight off. Do not pull on wires. Label each connector for proper reinstallation. Disconnect any temperature sensors or diagnostic connectors attached to the module.
   Torque spec

   Connector Bolts7 Nm (5 lb-ft)
7. 7

   Disconnect high-voltage connections
   Wearing high-voltage gloves, locate the high-voltage connectors attached to or near the thermal management module (orange cables). Remove the connector bolts using insulated tools. Carefully separate the connectors, keeping them away from any conductive surfaces. Verify again with multimeter that no voltage is present. Store connectors in a safe location.
   ⚠️Even with system de-energized, treat all orange cables as live. Use only insulated tools and maintain proper hand placement.
   Torque spec

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

   Remove mounting brackets
   Locate the thermal management module mounting brackets (typically 2-4 brackets securing the module to the battery pack housing). Remove the bracket bolts in a crisscross pattern to prevent binding. Support the module weight as the final bolts are removed, as the module weighs approximately 15-20 pounds.
   ⚠Module is heavy and awkwardly positioned. Use a second person or support device to prevent dropping.
   Torque spec

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

   Remove thermal management module
   With all connections and mounting bolts removed, carefully lower the thermal management module from the battery pack. If equipped with a thermal interface pad, note its orientation and condition. Inspect the mounting area on the battery pack for damage, corrosion, or coolant leaks. Clean the mounting surface with a lint-free cloth and inspect for debris.
10. 10

    Install new thermal management module
    If equipped, install a new thermal interface pad in the correct orientation on the battery pack mounting surface. Carefully position the new thermal management module into place, aligning all mounting holes. Verify all connectors and coolant ports are accessible before securing. Start all bracket bolts by hand to ensure proper thread engagement.
11. 11

    Secure mounting brackets
    Tighten the mounting bracket bolts in a crisscross pattern to ensure even pressure distribution. Torque all bracket bolts to specification. Verify the module is seated flush against the battery pack with no gaps or misalignment.
    Torque spec

    Bracket Bolts20 Nm (15 lb-ft)
12. 12

    Reconnect high-voltage connections
    Wearing high-voltage gloves and using insulated tools, reconnect the high-voltage connectors to the thermal management module. Ensure connectors are fully seated with audible click. Install and torque high-voltage connector bolts to specification. Verify connector locks are engaged and orange protective covers are properly installed.
    ⚠️Ensure connectors are completely dry and free of contamination before reconnecting. Any moisture or debris can cause arcing.
    Torque spec

    Connector Bolts7 Nm (5 lb-ft)
13. 13

    Reconnect electrical connectors and sensors
    Reconnect all low-voltage electrical connectors to the thermal management module, ensuring each connector clicks into place. Verify connector locks are engaged. Torque any sensor mounting bolts to specification if applicable. Route wiring away from any sharp edges or heat sources.
    Torque spec

    Sensor Bolts11 Nm (8 lb-ft)

    Connector Bolts7 Nm (5 lb-ft)
14. 14

    Reconnect coolant lines
    Install new O-rings on all coolant line fittings, lubricating lightly with clean coolant. Connect the inlet and outlet coolant lines to the thermal management module, ensuring lines are not twisted or kinked. Hand-tighten fittings first, then torque to specification using a calibrated torque wrench. Verify lines are properly routed and secured with any retention clips.
    Torque spec

    Coolant Line Fittings15 Nm (11 lb-ft)
15. 15

    Refill and bleed coolant system
    Using the specified ACDelco DEX-COOL orange coolant, refill the battery thermal management system through the fill port. Fill slowly to allow air to escape. Follow GM bleeding procedure: cycle the thermal management pump using scan tool to purge air from the system. Add coolant as needed to reach proper level. Check for leaks at all connection points while system is running.
    ⚠Use only the specified DEX-COOL coolant. Mixing coolant types will damage the system.

Reassembly

1. Reinstall the underbody shield, ensuring all fasteners are properly secured and torqued to specification.
2. Reconnect the 12-volt battery negative terminal.
3. Reinstall the high-voltage service disconnect: align the connector, push firmly until seated, rotate clockwise to lock, and install orange cover.
4. Reinstall the rear seat bottom cushion.
5. Using the scan tool, clear any stored diagnostic trouble codes and perform the battery thermal management system initialization procedure per GM service manual.
6. Verify proper coolant level after system reaches operating temperature; top off as needed.

Verification

• Using scan tool, verify battery thermal management module is communicating properly with no communication DTCs.
• Monitor coolant temperature data to confirm thermal management module is actively controlling temperature.
• Perform a test drive and monitor battery temperatures to ensure they remain within normal operating range (typically 15-35°C).
• Check for coolant leaks at all connection points after vehicle reaches operating temperature.
• Verify cooling pump operation using scan tool active tests.
• Confirm no warning lights or messages are displayed on instrument cluster.
• Document final scan tool data and save for service records.

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