This procedure covers the removal and replacement of the Power Electronics Module (PEM) on the 2025 Rivian EDV 500, which controls high-voltage distribution and motor inverter functions.

Warnings

Tools required

Parts

• Power Electronics Module (PEM) × 1 — Use OEM specification
• PEM thermal interface pad × 1 — Use OEM specification
• High-voltage connector seals × 4 — Use OEM specification
• Coolant line O-rings × 2 — Use OEM specification
• PEM mounting gasket × 1 — Use OEM specification

Fluids

• EV Battery/Motor Coolant — 10 qt

Preparation

1. Ensure vehicle has been off for at least 2 hours and is at ambient temperature
2. Position vehicle on level ground and engage parking brake
3. Verify you have high-voltage safety certification and proper PPE including insulated gloves
4. Disconnect the 12V auxiliary battery negative terminal
5. Access the high-voltage service disconnect located under the front hood
6. Remove the HV service disconnect using the proper service tool and wait 15 minutes minimum
7. Install lock-out/tag-out device on HV disconnect to prevent reconnection
8. Connect Rivian diagnostic tool and document any existing fault codes
9. Raise vehicle on lift to access underbody components if required for your specific repair access route
10. Remove front underbody panel to access PEM mounting location

Procedure

1. 1

   Verify high-voltage system de-energization
   Using a high-voltage rated multimeter, verify 0V DC at the HV bus bars and all PEM connection points. Test between positive and negative bus bars, then each bus bar to chassis ground. Document all readings. Do not proceed if any voltage above 0V is detected.
2. 2

   Drain coolant system
   Place drain pan under PEM coolant connections. Slowly open the coolant drain valve at the PEM coolant inlet to relieve system pressure. Drain approximately 10 quarts of EV Battery/Motor Coolant. Keep coolant clean for reuse if not contaminated.
3. 3

   Disconnect coolant lines from PEM
   Remove the quick-disconnect fittings at the PEM coolant inlet and outlet ports. Use a rag to catch residual coolant. Inspect O-rings for damage and set aside for replacement. Cap open coolant lines to prevent contamination.
4. 4

   Remove high-voltage cable connections
   Don high-voltage insulated gloves. Remove the protective covers from the HV connectors on the PEM. Label each cable connection for proper reassembly. Carefully disconnect the HV battery input cables, motor inverter output cables, and DC-DC converter connections. Support heavy cables with straps to prevent strain on connectors.
5. 5

   Disconnect low-voltage control connectors
   Locate and disconnect all low-voltage control harness connectors on the PEM. This typically includes the CAN bus communication connector, temperature sensor connectors, and status signal connectors. Use care with connector locking tabs to prevent breakage.
6. 6

   Remove PEM mounting hardware
   Remove the PEM mounting bolts securing the module to the vehicle chassis. The PEM is secured with multiple mounting points around its perimeter. Support the PEM weight during removal as the module weighs approximately 40-50 lbs.
7. 7

   Remove Power Electronics Module
   Carefully lower and remove the PEM from the vehicle. Work with an assistant due to module weight and awkward positioning. Avoid tilting the module excessively to prevent internal component damage. Place the removed PEM on a clean, static-free work surface.
8. 8

   Inspect mounting location and prepare for installation
   Clean the PEM mounting surface on the vehicle chassis. Inspect for any signs of damage, corrosion, or coolant leaks. Clean all electrical connection points. Verify all mounting studs and threads are undamaged. Remove the old thermal interface pad from the mounting surface.
9. 9

   Prepare new PEM for installation
   Remove protective shipping covers from the new PEM. Install the new thermal interface pad on the PEM mounting surface, ensuring proper alignment. Install new high-voltage connector seals on all HV terminals. Inspect all connectors for damage or contamination.
10. 10

    Install new Power Electronics Module
    With an assistant, carefully position the new PEM into the mounting location. Align all mounting holes and ensure the thermal interface pad makes full contact with the cooling surface. Install mounting bolts hand-tight initially, then torque in a cross-pattern to ensure even mounting pressure. Note: Specific torque values should be obtained from factory service manual.
11. 11

    Reconnect low-voltage control connectors
    Reconnect all low-voltage control harness connectors to the new PEM in the reverse order of removal. Ensure all connector locks engage fully. Verify each connection by gently pulling on the connector body.
12. 12

    Reconnect high-voltage cables
    Don high-voltage insulated gloves. Following your labels from disassembly, reconnect each high-voltage cable to the correct PEM terminal. Torque HV connections according to factory specifications. Install protective covers over all HV connections. Remove cable support straps.
13. 13

    Reconnect coolant lines
    Install new O-rings on coolant line fittings. Reconnect coolant inlet and outlet lines to the PEM, ensuring quick-disconnect fittings are fully seated and locked. Verify connections by pulling on each line.
14. 14

    Refill coolant system
    Refill the EV Battery/Motor Coolant system with 10 quarts of coolant through the fill port. Follow the factory bleeding procedure to remove air from the system. Run the coolant pump through the diagnostic tool to circulate coolant and verify proper flow.
15. 15

    Perform system programming and calibration
    Connect Rivian diagnostic tool and perform PEM registration to the vehicle ECU. This pairs the new PEM with the vehicle's control systems. Complete all required calibration procedures including motor position learning, high-voltage system verification, and thermal management system calibration. Clear any installation-related fault codes.

Reassembly

1. Reinstall front underbody panel and ensure all fasteners are secure
2. Lower vehicle from lift if raised
3. Remove lock-out/tag-out device and reinstall HV service disconnect
4. Reconnect 12V auxiliary battery negative terminal
5. Verify all tools and parts have been removed from vehicle

Verification

• With diagnostic tool connected, verify no high-voltage system fault codes are present
• Perform a high-voltage system insulation resistance test to verify proper installation
• Verify coolant system is at proper level and no leaks are present at PEM connections
• Enable high-voltage system and verify PEM powers up correctly with no warning lights
• Perform a controlled test drive at low speed to verify motor control functions properly
• Monitor PEM temperature during test drive to ensure proper thermal management
• Verify all vehicle functions including regenerative braking and full power delivery
• Re-check for fault codes after test drive and document final vehicle status

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