This procedure covers the removal and replacement of the Power Electronics Module (PEM) on a 2023 Rivian EDV 500, which manages high-voltage power distribution and conversion for the electric drivetrain.

Warnings

Tools required

Parts

• Power Electronics Module (PEM) × 1 — Use OEM specification
• HV coolant hose O-rings × 4 — Use OEM specification
• HV connector seals × 3 — Use OEM specification
• Thermal interface pad × 1 — Use OEM specification
• Cable ties × 10 — Use OEM specification

Fluids

• EV Battery/Motor Coolant — 10 qt

Preparation

1. Park vehicle on level surface and engage parking brake
2. Ensure vehicle is in Park mode and powered off
3. Connect Rivian diagnostic software and activate Service Mode for high-voltage systems
4. Document any diagnostic trouble codes and save vehicle configuration
5. Remove 12V auxiliary battery negative terminal and wait 5 minutes
6. Access high-voltage service disconnect located in front trunk area
7. Remove HV service disconnect using proper lockout/tagout procedure
8. Wait minimum 15 minutes for capacitor discharge
9. Don high-voltage insulated gloves and safety equipment
10. Verify zero voltage at HV busbars using calibrated multimeter (must read <5V DC)
11. Place high-voltage warning tags on steering wheel and service disconnect location
12. Raise vehicle on lift to comfortable working height

Procedure

1. 1

   Drain HV coolant system
   Place drain pan under vehicle beneath PEM coolant drain point. Open coolant drain valve on the low-voltage side of the cooling system. Drain approximately 10 quarts of EV coolant. Note coolant condition and any contamination. Close drain valve when flow stops.
2. 2

   Remove underbody shield panels
   Remove front underbody shield panels to access PEM mounting area. Remove plastic fasteners and mounting bolts securing shields. Set aside panels in clean area for reinstallation.
3. 3

   Disconnect low-voltage connectors
   Locate and disconnect all low-voltage control connectors from PEM. This includes CAN bus communication connectors, sensor inputs, and control signal harnesses. Press connector release tabs and carefully pull connectors straight out. Label each connector for proper reinstallation.
4. 4

   Disconnect HV coolant lines
   Verify system is depressurized and cool. Disconnect quick-connect coolant lines from PEM inlet and outlet ports. Press release collars and pull lines straight out. Have shop towels ready to catch residual coolant. Cap open lines and ports immediately to prevent contamination.
5. 5

   Remove HV cable connections
   Wearing HV insulated gloves, remove protective covers from high-voltage cable connections on PEM. Remove mounting bolts securing HV positive and negative cable lugs to PEM input terminals. Remove battery pack HV cables from output terminals. Carefully support cable weight to prevent strain on connections. Cover all exposed HV terminals with insulating caps.
6. 6

   Disconnect drive unit HV cables
   Remove high-voltage cables connecting PEM output to front and rear drive units. Remove mounting bolts from cable lugs at PEM-side connections. Support cables and secure away from work area. Install insulating caps on all exposed HV terminals.
7. 7

   Support PEM weight
   Position engine hoist or lift table under PEM assembly. Attach lifting straps to PEM mounting points using proper lift points. Take up slack in straps to support PEM weight but do not lift yet. Ensure PEM is balanced and stable on lifting equipment.
8. 8

   Remove PEM mounting fasteners
   Remove all mounting bolts securing PEM to vehicle chassis. There are typically 6-8 primary mounting bolts around perimeter of PEM. Remove any ground straps or secondary mounting brackets. Keep all fasteners organized by location for reinstallation.
9. 9

   Remove PEM from vehicle
   Verify all connections and fasteners are removed. Slowly lower PEM assembly using hoist/lift table while guiding clear of vehicle structure. Watch for any remaining connections or obstructions. Once clear of vehicle, transport PEM to clean work surface. Inspect mounting location and clean any debris or coolant residue.
10. 10

    Prepare new PEM for installation
    Unpack new PEM and verify correct part number matches vehicle specification. Inspect all mounting surfaces and connection points. Install new thermal interface pad on mounting surface if required. Apply dielectric grease to HV connector sealing surfaces. Transfer any necessary brackets or mounting hardware from old PEM to new unit if not included.
11. 11

    Install new PEM
    Position new PEM on hoist/lift table and raise into vehicle mounting location. Align PEM with chassis mounting points and guide into position carefully. Start all mounting bolts by hand to ensure proper alignment. Torque mounting bolts in star pattern to proper specification. Verify PEM is seated fully against mounting surface with no gaps.
12. 12

    Reconnect HV drive unit cables
    Remove insulating caps from drive unit HV cable terminals and PEM output terminals. Clean mating surfaces with non-conductive brush if needed. Position cable lugs on PEM output terminals ensuring proper polarity. Install mounting bolts and torque to specification. Verify connections are tight and cables are properly routed without strain.
13. 13

    Reconnect HV battery cables
    Remove insulating caps from battery HV cables and PEM input terminals. Clean all mating surfaces. Position HV positive and negative cable lugs on correct PEM input terminals. Install and torque mounting bolts to specification. Install protective covers over all HV connections. Verify all connections are secure and properly insulated.
14. 14

    Reconnect coolant lines
    Install new O-rings on coolant line quick-connect fittings. Lubricate O-rings with small amount of fresh coolant. Push coolant lines into PEM ports until positive click is heard/felt. Pull back on lines to verify secure connection. Route lines to avoid contact with hot or moving components.
15. 15

    Reconnect low-voltage connectors and complete reassembly
    Reconnect all low-voltage control connectors to PEM following labels applied during removal. Ensure all connectors fully seat and lock. Install underbody shield panels and secure with all fasteners. Refill HV coolant system with fresh EV Battery/Motor Coolant to proper level. Bleed air from cooling system per manufacturer procedure. Reinstall HV service disconnect. Reconnect 12V auxiliary battery.

Reassembly

1. Double-check all HV connections are properly torqued and insulated
2. Verify all coolant lines are securely connected and system is properly filled and bled
3. Confirm all low-voltage connectors are fully seated
4. Ensure underbody panels are properly reinstalled and secure
5. Remove all lockout/tagout tags and warning notices

Verification

• Connect Rivian diagnostic software and clear Service Mode
• Perform PEM commissioning procedure using diagnostic software
• Verify PEM is recognized by vehicle systems and communicating properly
• Check for diagnostic trouble codes and address any issues
• With vehicle in READY mode, verify PEM cooling fan operation
• Check for coolant leaks around all connections
• Perform HV insulation resistance test (must be >500 ohms/volt minimum)
• Test drive vehicle to verify proper operation of both drive units
• Monitor PEM temperatures during test drive to ensure proper cooling
• Perform final diagnostic scan and verify all systems operational

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