EV Coolant Pump

This procedure covers the removal and replacement of the EV coolant pump on the 2023 Chevrolet Bolt EUV, which circulates coolant through the battery thermal management system and drive unit.

Warnings

Tools required

Parts

• EV coolant pump assembly × 1 — Use OEM specification
• Coolant pump O-ring seal kit × 1 — Use OEM specification
• Hose clamps (if reusing is not recommended) × 2 — Use OEM specification

Fluids

• ACDelco DEX-COOL (Orange) — 2 qt

Preparation

1. Ensure the vehicle has been off for at least 2 hours and is completely cool
2. Park vehicle on level surface and engage parking brake
3. Verify high-voltage system is disabled by checking the instrument cluster for any active HV warnings
4. Disconnect the 12V battery negative terminal and wait 2 minutes
5. Remove the front underbody shield using T30 Torx fasteners to access the coolant pump area
6. Place drain pan under the EV coolant pump location (driver side of motor compartment)
7. Locate the EV coolant reservoir and note the current coolant level for reference

Procedure

1. 1

   Relieve coolant system pressure
   Slowly loosen the EV coolant reservoir cap (orange cap labeled 'Electric Drive Unit Coolant') a quarter turn to release any residual pressure. Wait for any hissing to stop, then remove the cap completely. Set the cap aside in a clean location.
2. 2

   Drain coolant from pump area
   Position the drain pan directly beneath the coolant pump. Using hose clamp pliers, reposition the hose clamps on both inlet and outlet hoses at the pump. Carefully twist and pull the hoses off the pump fittings. Allow coolant to drain into the pan. Expect approximately 1-2 quarts of coolant loss.
   ⚠Coolant may still be warm even after cooling period. Wear protective gloves and glasses.
3. 3

   Disconnect electrical connector
   Locate the electrical connector on the coolant pump body. Press the locking tab and carefully disconnect the connector. Inspect the connector pins for corrosion or damage. If a connector bolt is present securing the harness bracket, remove it using a 10mm socket.
   Torque spec

   Connector Bolts7 Nm (5 lb-ft)
4. 4

   Remove coolant pump mounting bolts
   Using a 13mm socket, remove the coolant pump mounting bolts. There are typically two mounting bolts securing the pump to its bracket. Support the pump with one hand while removing the final bolt to prevent it from falling.
   Torque spec

   Mounting Bolts27 Nm (20 lb-ft)
5. 5

   Remove coolant pump assembly
   Carefully extract the coolant pump from its mounting location. Tilt and rotate as needed to clear surrounding components. Place the old pump in the drain pan to catch any residual coolant. Inspect the mounting bracket for damage or corrosion.
6. 6

   Inspect and clean mounting surfaces
   Thoroughly clean the mounting bracket and coolant line connection points with a lint-free cloth. Remove any old coolant residue, debris, or corrosion. Inspect the coolant hoses for cracks, swelling, or deterioration. Replace hoses if any damage is found.
7. 7

   Prepare new coolant pump
   Unpack the new coolant pump and verify it matches the original unit. Install new O-rings on the pump inlet and outlet fittings. Lightly lubricate the O-rings with fresh DEX-COOL coolant to ease installation and prevent tearing. Verify the pump rotates freely by hand if applicable.
8. 8

   Install new coolant pump
   Position the new coolant pump into the mounting bracket, aligning the mounting holes. Start both mounting bolts by hand to ensure proper thread engagement before tightening. Torque the mounting bolts in a cross pattern to the specified value.
   Torque spec

   Mounting Bolts27 Nm (20 lb-ft)
9. 9

   Reconnect coolant lines
   Install the inlet and outlet coolant hoses onto the pump fittings. Ensure each hose is fully seated onto the fitting barbs. Position new or reused hose clamps over the hose connection points and tighten to the specified torque. Verify clamps are positioned correctly and not pinching the hoses.
   Torque spec

   Hose Clamps3 Nm (2 lb-ft)
10. 10

    Reconnect electrical connector
    Reconnect the electrical connector to the coolant pump, ensuring it clicks securely into place. Verify the locking tab is fully engaged. If a connector bolt secures a harness bracket, install and torque it to specification.
    Torque spec

    Connector Bolts7 Nm (5 lb-ft)
11. 11

    Refill coolant system
    Add fresh ACDelco DEX-COOL coolant to the EV coolant reservoir until it reaches the FULL COLD mark. Add coolant slowly to minimize air introduction. Do not overfill. Install the reservoir cap hand-tight.
    ℹ️The system will need to be burped of air. Initial fill should be to the FULL COLD line only.
12. 12

    Bleed air from coolant system
    Reconnect the 12V battery negative terminal. With the vehicle still off, turn the ignition to ON/RUN mode without pressing the brake pedal. Allow the EV coolant pump to run through its self-priming cycle for approximately 3-5 minutes. Monitor the coolant reservoir and add coolant as the level drops while air is purged. The pump may cycle on and off automatically.
13. 13

    Final inspection and test
    With the vehicle still in RUN mode, inspect all connections at the coolant pump for leaks. Check that the pump is operating smoothly without unusual noise. Turn off the vehicle and recheck the coolant level, topping off to the FULL COLD mark if needed. Reinstall the front underbody shield, torquing all T30 fasteners to specification.

Reassembly

1. Reinstall the front underbody shield using all original T30 Torx fasteners
2. Double-check all hose clamps and electrical connections for security
3. Verify the coolant reservoir cap is properly installed
4. Clean any spilled coolant from surfaces to prevent slipping hazards

Verification

• Start the vehicle and allow it to run in READY mode for 10 minutes while monitoring coolant temperature on the instrument cluster
• Check for any coolant leaks at the pump connections while the system is pressurized
• Verify the coolant level is at the FULL HOT mark when the system reaches operating temperature
• Listen for unusual pump noise or vibration during operation
• Test drive the vehicle and monitor for any battery thermal management warnings or errors
• Recheck coolant level after the vehicle has cooled completely (at least 2 hours) and top off if necessary
• Monitor coolant level over the next few days and top off as needed until the system stabilizes

Related trouble codes on this vehicle

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