EV Thermal Management System

Service or replace components of the EV thermal management system, including coolant system inspection, pump replacement, and thermal valve servicing for battery and motor temperature control.

Warnings

Tools required

Parts

• EV Battery/Motor Coolant × 1 — Use OEM specification
• Coolant hose clamps × 4 — Use OEM specification
• Thermal management system O-rings × 1 — Use OEM specification
• Coolant reservoir cap × 1 — Use OEM specification as needed

Fluids

• EV Battery/Motor Coolant — 10 qt

Preparation

1. Park vehicle on level surface and apply parking brake. Ensure vehicle has been off for minimum 2 hours.
2. Verify key fob is at least 20 feet away from vehicle to prevent unintended system activation.
3. Connect Rivian diagnostic software and verify no active thermal management faults. Record baseline system parameters.
4. Access HV disconnect switch located under second row seat. Open cover and rotate disconnect lever counterclockwise to OFF position.
5. Wait 5 minutes for HV capacitors to discharge. Verify voltage at HV busbars reads 0V DC using calibrated high-voltage multimeter.
6. Install HV lockout/tagout device on disconnect switch. Attach warning tag with technician name and date.
7. Remove underbody aero shields to access thermal system components: front shield (8 fasteners), mid-section shield (12 fasteners).
8. Raise and safely support vehicle on jack stands at manufacturer-specified lift points. Verify stability before working underneath.
9. Place coolant drain pan beneath battery pack drain valve location (driver side, mid-pack position).

Procedure

1. 1

   Depressurize coolant system
   Using diagnostic software, navigate to Thermal Management menu and select 'System Depressurization Mode'. Allow coolant pump to run cycle (approximately 3 minutes) to relieve system pressure. Slowly loosen coolant reservoir cap one full turn and wait for any residual pressure release. Remove cap completely and set aside with new seal facing up.
2. 2

   Drain primary coolant circuit
   Locate battery pack coolant drain valve on driver side frame rail. Attach drain hose to valve nipple and route to drain pan. Open drain valve by turning counterclockwise 2 full turns. Allow gravity drain for 15 minutes. Use diagnostic software to activate coolant pump in purge mode (3x 30-second cycles) to evacuate coolant from battery pack channels and motor cooling jackets. Close drain valve when flow stops.
3. 3

   Disconnect thermal system electrical connectors
   Locate and disconnect electrical connectors for: primary coolant pump (passenger side, forward of battery pack), thermal expansion valve (driver side, mid-pack), coolant temperature sensors (3 locations: battery inlet/outlet, motor inlet), and coolant flow meter (if equipped). Depress connector locks and pull straight away from components. Secure connectors away from work area with zip ties to prevent contamination.
4. 4

   Remove coolant hoses from failed or service components
   Identify components requiring service based on diagnostic trouble codes or inspection results. Use hose clamp pliers to compress spring clamps and slide away from connection points. For thermal pump replacement: disconnect inlet hose (19mm), outlet hose (19mm), and bypass hose (16mm). For thermal valve service: disconnect control hoses (12mm each). Mark hose positions with tape labels before removal to ensure correct reassembly. Inspect hoses for swelling, cracking, or degradation; replace if necessary.
5. 5

   Remove thermal management component mounting hardware
   For coolant pump removal: remove three mounting bolts securing pump bracket to battery pack frame rail. For thermal expansion valve: remove two mounting bolts from valve body bracket. Support component weight while removing final fastener. Carefully extract component from mounting location, tilting to drain residual coolant into drain pan. Inspect mounting surfaces for corrosion or damage.
6. 6

   Inspect coolant passages and clean mounting surfaces
   With components removed, inspect exposed coolant passages in battery pack and motor cooling channels for debris, scale buildup, or blockage. Use compressed air (maximum 30 PSI) to blow out passages if contamination is found. Clean component mounting surfaces with lint-free shop towels and isopropyl alcohol. Inspect all coolant passage O-ring grooves for damage or scoring. Replace any damaged O-rings with new OEM parts, lubricating with fresh coolant before installation.
7. 7

   Install replacement or serviced components
   Position new or serviced thermal management component into mounting location, ensuring proper alignment with coolant passage ports. Install mounting hardware finger-tight initially. Verify component is properly seated and aligned before final tightening. Since no torque specifications are provided in database, tighten mounting bolts in star pattern to ensure even pressure distribution and prevent component distortion. Reconnect electrical connectors, ensuring positive lock engagement with audible click.
8. 8

   Reconnect coolant hoses
   Reconnect coolant hoses to components in reverse order of removal, referencing position labels applied during disassembly. Ensure hoses are fully seated onto nipples with no gap visible between hose end and component shoulder. Install new hose clamps (or reposition original spring clamps) 5-10mm from hose end. For critical connections (pump inlet/outlet), use two clamps per connection for redundancy. Verify no hoses are kinked, twisted, or contacting sharp edges.
9. 9

   Refill coolant system using vacuum method
   Connect vacuum fill tool to coolant reservoir. Draw vacuum on system to -25 inHg (-85 kPa) minimum. Hold vacuum for 5 minutes and verify it does not decay (indicates no leaks). With vacuum maintained, submerge fill tool hose into fresh EV Battery/Motor Coolant container. Release vacuum to allow coolant to be drawn into system. Continue until coolant level reaches MAX mark on reservoir and no more fluid is drawn in. This should consume approximately 10 quarts total.
10. 10

    Perform system bleed procedure
    Using Rivian diagnostic software, navigate to Thermal Management System Bleed procedure. Select 'Automated Bleed Cycle'. Software will activate coolant pump in specific sequence to purge air from battery cooling channels, motor cooling jacket, and auxiliary circuits. Process takes approximately 15 minutes. Monitor coolant level during bleed and add fluid as needed to maintain MAX level. Watch for air bubbles in reservoir; bleeding is complete when no bubbles appear for 2 minutes of pump operation.
11. 11

    Pressure test thermal system
    Install coolant pressure tester on reservoir. Pressurize system to 15 PSI (103 kPa). System should hold pressure for 10 minutes with no more than 1 PSI loss. Carefully inspect all service connection points for coolant leaks. Check pump mounting interface, hose connections, and O-ring seals. If leaks detected, depressurize system, repair leak source, and retest. Release pressure tester once verification is complete.
12. 12

    Restore HV system and perform functional test
    Remove HV lockout/tagout device. Rotate HV disconnect switch clockwise to ON position. Replace access cover under second row seat. Using diagnostic software, clear any stored thermal management fault codes. Select 'Thermal System Function Test' in software. This activates all thermal components through their full operating range while monitoring temperatures, flow rates, and pressures. Verify all parameters are within specification ranges shown in software. Test duration is approximately 10 minutes.
13. 13

    Verify system operation under load
    With diagnostic software still connected and monitoring thermal parameters, power on vehicle. Select Drive mode and allow vehicle to run stationary with accelerator at 25% for 5 minutes to generate motor heat load. Verify coolant pump activates, temperatures remain stable, and thermal valve modulates correctly. Monitor battery pack temperature distribution; all cell modules should remain within 3°C of each other. If thermal performance is not within parameters, investigate for air pockets or component malfunction.
14. 14

    Complete system check and reinstall shields
    Perform final visual inspection of all thermal system connections and components. Verify no coolant leaks, all electrical connectors are locked, and no tools or materials remain in service area. Check coolant level one final time and top off if needed to MAX mark. Install new reservoir cap with fresh seal. Reinstall underbody aero shields in reverse order of removal, ensuring all fasteners are properly seated and retention clips engaged.

Reassembly

1. Ensure all coolant hoses are properly routed and secured with appropriate clamps at each connection point
2. Verify all electrical connectors are fully engaged with positive locks engaged and no exposed terminals
3. Confirm HV disconnect switch is in ON position and access cover is reinstalled before returning vehicle to service
4. Top off coolant reservoir to MAX mark after system has fully cooled from test procedure
5. Reinstall all underbody shields and verify all fasteners are present and properly torqued

Verification

• Using Rivian diagnostic software, verify no active or pending thermal management fault codes are present
• Confirm coolant level is at MAX mark with system at operating temperature (60-70°C)
• Verify thermal system pressure holds 15 PSI for 10 minutes with no detectable leaks
• Test drive vehicle for minimum 15 minutes, including highway speeds and moderate acceleration to generate heat load
• After test drive, verify battery pack temperature distribution is within 3°C across all modules using diagnostic software
• Confirm coolant pump activates and modulates correctly based on thermal demand during drive cycle
• Inspect all service connection points for coolant seepage after test drive with vehicle cooled
• Document all diagnostic data, fault codes cleared, and fluid quantities used in vehicle service record

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