This procedure covers the removal and replacement of the main high-voltage relay in a 2023 Rivian EDV 500, which controls power distribution from the battery pack to the drive motors and other high-voltage systems.

Warnings

Tools required

Parts

• Main high-voltage relay assembly × 1 — Use OEM specification
• HV connector seal (if damaged) × 1 — Use OEM specification
• Thermal interface pad (if equipped) × 1 — Use OEM specification

Preparation

1. Park vehicle on level ground and engage parking brake
2. Place high-voltage warning signs around the vehicle
3. Ensure a second qualified person is present for safety
4. Remove all jewelry, watches, and conductive accessories
5. Connect Rivian diagnostic scanner and verify no active faults
6. Document all DTC codes before beginning work
7. Ensure vehicle has been powered off for at least 10 minutes
8. Disconnect 12V auxiliary battery negative terminal
9. Wait an additional 5 minutes for capacitor discharge

Procedure

1. 1

   Access HV disconnect and lockout
   Put on high-voltage safety gloves. Open the rear service panel to access the high-voltage disconnect switch. Rotate the HV disconnect lever to the OFF position and remove the service disconnect plug. Place the disconnect plug in your toolbox to prevent accidental reconnection. Install lockout/tagout device on the disconnect location.
2. 2

   Verify zero voltage state
   Using a high-voltage rated multimeter, verify zero voltage at the HV disconnect terminals. Check between positive and negative terminals, positive to chassis ground, and negative to chassis ground. All readings must be below 5V DC. Document voltage readings. Wait an additional 5 minutes if any voltage is detected.
3. 3

   Remove underbody splash shield
   Remove the front underbody splash shield by removing the T25 Torx fasteners along the perimeter (approximately 12 fasteners). Carefully lower the shield and set aside. This provides access to the HV junction box where the main relay is located.
4. 4

   Locate main relay assembly
   Identify the main relay assembly within the HV junction box mounted to the front subframe. The main relay is typically a large rectangular component with orange high-voltage cable connections. Note the orientation and routing of all cables before disconnection.
5. 5

   Remove HV junction box cover
   Remove the HV junction box protective cover by removing the T30 Torx bolts (typically 6 bolts). Carefully lift the cover away, being mindful of any attached ground straps. Set cover aside in a clean area.
6. 6

   Disconnect low-voltage control connector
   Locate the low-voltage control connector on the main relay (typically a gray or black multi-pin connector). Press the locking tab and carefully disconnect the connector. Secure the connector away from the work area to prevent damage.
7. 7

   Remove HV cable connections
   Wearing HV safety gloves, identify the high-voltage input and output cables (orange cables). Remove the 12mm bolts securing each HV cable terminal to the relay. Carefully separate the cables from the relay terminals and cap each exposed terminal with insulating covers. Support cables to prevent strain on remaining connections.
8. 8

   Remove main relay mounting hardware
   Remove the relay mounting bolts (typically two to four 10mm bolts) securing the main relay to the junction box mounting bracket. Note any ground straps or additional hardware that must be removed. Support the relay during removal.
9. 9

   Extract main relay assembly
   Carefully withdraw the main relay from the HV junction box. Avoid contact with surrounding components. If equipped with a thermal interface pad, note its position for reassembly. Inspect the mounting area for any debris or contamination and clean if necessary.
10. 10

    Inspect and prepare new relay
    Inspect the new main relay for shipping damage. Verify part number matches the removed unit. If the relay includes a thermal interface pad, ensure it is properly positioned. Check that all mounting provisions and connector locations match the original.
11. 11

    Install new main relay
    Position the new main relay into the HV junction box mounting location, aligning mounting holes and ensuring proper orientation. If equipped, verify thermal interface pad is correctly positioned. Install mounting bolts and tighten in a cross pattern to ensure even seating. Do not fully torque at this stage.
12. 12

    Reconnect HV cables
    Remove insulating caps from HV cable terminals. Clean terminal contact surfaces with electrical contact cleaner if needed. Position HV cables to relay terminals, ensuring correct polarity. Install terminal bolts and tighten securely. Verify cables are properly seated and show no gaps at terminals.
13. 13

    Reconnect low-voltage control connector
    Route the low-voltage control connector to the relay. Align and firmly press the connector onto the relay until the locking tab clicks into place. Gently tug to verify secure connection. Ensure no pins are bent or misaligned.
14. 14

    Reinstall HV junction box cover
    Verify all connections are secure and no tools remain in the junction box. Position the HV junction box cover, reconnecting any ground straps. Install the T30 Torx bolts and tighten in a star pattern to ensure proper seal. Verify cover gasket is properly seated.
15. 15

    System verification and testing
    Reinstall the underbody splash shield with all T25 Torx fasteners. Reconnect the 12V auxiliary battery. Remove lockout device and reinstall the HV service disconnect plug, rotating to the ON position. Using the diagnostic scanner, clear any stored DTCs, then perform the main relay self-test procedure. Verify no new fault codes appear. Power on the vehicle and verify all high-voltage systems initialize correctly.

Reassembly

1. Ensure all high-voltage cable connections are torqued and secured properly
2. Verify HV junction box cover is sealed and all fasteners are tight
3. Confirm underbody splash shield is reinstalled with all clips and fasteners
4. Double-check that HV service disconnect is in the ON position
5. Remove all high-voltage warning signs from around the vehicle

Verification

• Connect diagnostic scanner and verify no active DTC codes related to the main relay
• Perform a complete vehicle self-test using the diagnostic scanner
• Verify vehicle powers on normally and READY indicator illuminates
• Test drive vehicle to verify normal operation and full power availability
• Monitor for any warning lights or error messages on the instrument cluster
• Using diagnostic scanner, verify main relay actuation cycles correctly during power-up sequence
• Check that battery SOC, motor temperatures, and all high-voltage system parameters display normally

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