This procedure covers the removal and replacement of the Power Electronics Module (PEM) on the 2022 Rivian EDV 500, which controls high-voltage power distribution to the dual electric motors.

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 hose O-rings × 2 — Use OEM specification
• PEM mounting gasket × 1 — Use OEM specification

Fluids

• EV Battery/Motor Coolant — 2 qt

Preparation

1. Park vehicle on level surface and engage parking brake
2. Turn off vehicle and remove key fob at least 15 feet away from vehicle
3. Chock rear wheels securely
4. Raise vehicle on lift or support securely on jack stands
5. Remove underbody panels to access PEM area in front motor compartment
6. Allow vehicle to sit for minimum 30 minutes to ensure all high-voltage systems are de-energized
7. Put on high-voltage safety gloves and have insulated tools ready
8. Connect diagnostic scan tool and verify no DTCs related to high-voltage system integrity
9. Take photos of all harness routing and connector positions around PEM

Procedure

1. 1

   Disconnect 12V battery
   Locate the 12V battery in the front storage compartment. Disconnect the negative terminal first, then the positive terminal. Secure cables away from terminals. Wait 5 minutes for all vehicle systems to fully power down.
2. 2

   Access and verify high-voltage disconnect
   Locate the high-voltage service disconnect in the battery pack area. Remove the service disconnect cover. Pull the high-voltage service disconnect lever to the OFF position. Lock out the disconnect with appropriate tag. Wait minimum 15 minutes for high-voltage capacitors to discharge.
3. 3

   Verify zero voltage state
   Using a high-voltage capable digital multimeter, verify zero voltage (less than 5V DC) across all high-voltage bus bars and at the PEM input terminals. Test between positive and negative, positive and chassis ground, and negative and chassis ground. Document all readings. Only proceed if all readings are below 5V DC.
4. 4

   Drain EV cooling system
   Locate the EV cooling system drain valve under the vehicle near the front motor area. Position drain pan with minimum 12 quart capacity beneath drain point. Open drain valve and allow coolant to drain completely. Close drain valve when complete. Note the amount drained for refill reference.
5. 5

   Disconnect PEM coolant lines
   Wearing appropriate gloves, locate the two coolant quick-connect fittings on the PEM inlet and outlet. Press the release tabs on each quick-connect and pull hoses straight off. Expect residual coolant spillage. Inspect O-rings on both hose ends and set aside for replacement during reassembly. Cap or plug coolant ports on PEM to prevent contamination.
6. 6

   Disconnect low-voltage control harnesses
   Locate the three low-voltage control connectors on the PEM: primary control connector (black, 48-pin), secondary communication connector (gray, 24-pin), and temperature sensor connector (green, 4-pin). Press release tabs and carefully disconnect each connector. Secure connectors away from work area.
7. 7

   Disconnect high-voltage power cables
   Wearing high-voltage gloves, locate the four high-voltage connections: battery positive input (orange cable), battery negative input (blue cable), front motor output (orange, dual conductor), and rear motor output (orange, dual conductor). Remove the protective covers from each connection point. Using insulated tools, remove the securing bolts from each high-voltage terminal in the sequence: front motor, rear motor, battery negative, battery positive. Carefully route cables away and secure with non-conductive ties.
8. 8

   Remove PEM mounting brackets
   Locate the four primary mounting bolts securing the PEM to the structural frame. These are positioned at each corner of the PEM assembly. Support the PEM weight from below using a suitable stand or have an assistant support it. Remove the four mounting bolts using appropriate socket. Note: PEM weighs approximately 45 lbs.
9. 9

   Remove PEM assembly
   With mounting bolts removed and all connections disconnected, carefully lower and remove the PEM assembly from the vehicle. Keep unit level during removal to prevent internal component damage. Place PEM on clean, insulated work surface. Inspect mounting area and cooling interface for damage, corrosion, or contamination.
10. 10

    Prepare mounting surface and new PEM
    Clean the PEM mounting surface thoroughly, removing any debris, old gasket material, or corrosion. Inspect coolant port threads and electrical mounting points for damage. Unpack new PEM and verify part number matches vehicle specification. Install new thermal interface pad on mounting surface. Apply dielectric grease to high-voltage terminal threads.
11. 11

    Install new PEM assembly
    With assistance or using a support stand, carefully lift new PEM into position, ensuring proper alignment with mounting holes and ensuring thermal interface pad remains properly positioned. Install the four mounting bolts finger-tight initially. Torque mounting bolts to specification in a cross-pattern sequence (specification not provided in database - refer to Rivian service manual for exact values).
12. 12

    Connect high-voltage power cables
    Wearing high-voltage gloves and using insulated tools, reconnect high-voltage cables in reverse order of removal: battery positive first, battery negative second, rear motor output third, front motor output last. Ensure all terminals are clean and properly seated. Torque high-voltage terminal bolts to specification (refer to Rivian service manual). Install new high-voltage connector seals on each connection. Install protective covers over all high-voltage terminals.
13. 13

    Reconnect low-voltage harnesses and coolant lines
    Reconnect the three low-voltage control connectors in reverse order: temperature sensor (green), secondary communication (gray), and primary control (black). Ensure each connector clicks securely into place. Install new O-rings on coolant hose quick-connect fittings. Reconnect coolant inlet and outlet lines, pushing firmly until they click into place. Tug gently to verify secure connection.
14. 14

    Refill EV cooling system
    Using specified EV Battery/Motor Coolant, refill the cooling system through the fill point until proper level is reached. Reference the amount drained earlier (typically 2 quarts loss during PEM replacement). Burp the system by running coolant pump through diagnostic scan tool if available, or by carefully starting vehicle and monitoring for air pockets. Top off coolant to proper level.
15. 15

    Perform high-voltage reconnection and system test
    Reconnect 12V battery (positive first, then negative). Using diagnostic scan tool, perform PEM initialization and configuration procedure per Rivian service protocol. Reinstall high-voltage service disconnect and restore to ON position. With scan tool connected, verify all high-voltage systems show proper voltage readings and no isolation faults are present. Perform PEM self-test and verify all communication networks are functioning. Clear any stored DTCs related to the service disconnect.

Reassembly

1. Reinstall all underbody panels and fasteners removed for access
2. Verify all tools and equipment are removed from vehicle
3. Double-check all high-voltage connections have protective covers installed
4. Verify coolant level is correct and system is properly bled of air
5. Remove wheel chocks and lower vehicle from lift

Verification

• Using diagnostic scan tool, verify no DTCs are present in any control module
• Verify PEM reports correct part number and software version in scan tool
• Check that high-voltage system shows proper isolation resistance (typically above 500 ohms/volt)
• Verify coolant system is maintaining proper temperature and no leaks are present at PEM connections
• Perform test drive at low speed in parking area to verify motor function and power delivery
• Monitor PEM temperature through scan tool during test to verify cooling system function
• Verify regenerative braking functions properly in both directions
• After test drive, re-check all high-voltage connections for proper seating and no heat damage
• Final scan for DTCs and verify all systems operational

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