This procedure covers the removal and replacement of the Battery Junction Box (BJB) on the 2025 Rivian EDV 500, which manages high-voltage power distribution between the battery pack and vehicle systems.

Warnings

Tools required

Parts

• Battery Junction Box assembly × 1 — Use OEM specification
• High-voltage connector seals × 1 — Use OEM specification
• Junction box mounting hardware kit × 1 — Use OEM specification
• HV cable protective covers × 1 — Use OEM specification
• Cable tie assortment × 1 — OEM or high-temp automotive grade

Preparation

1. Verify technician has valid EV high-voltage safety certification and training specific to Rivian commercial vehicles
2. Ensure vehicle is parked on level surface in well-ventilated area with non-conductive flooring if possible
3. Connect Rivian diagnostic software and document any existing fault codes
4. Place 'HIGH VOLTAGE WORK IN PROGRESS' warning signs on vehicle and in work area
5. Verify fire extinguisher rated for electrical fires (Class C) is immediately accessible
6. Remove any metal jewelry, watches, or conductive accessories
7. Confirm high-voltage insulated gloves are within certification date and visually inspect for damage
8. Gather all photographs and technical service bulletins related to Battery Junction Box for this model year

Procedure

1. 1

   Disable high-voltage system
   Using diagnostic software, place vehicle into service mode. Turn off vehicle and remove key fob from cabin. Open the front hood and locate the 12V battery in the front compartment. Disconnect 12V negative terminal first, then positive terminal. Wait 2 minutes for all vehicle systems to power down completely.
   ℹ️Service mode prevents unintended HV system activation during repair.
2. 2

   Access HV disconnect location
   Remove the lower front access panel beneath the vehicle using appropriate fasteners. Locate the manual service disconnect (MSD) near the battery pack front section. The MSD will have an orange handle or cover indicating high-voltage components.
   ⚠Some coolant may drip when removing access panels. Position drain pan accordingly.
3. 3

   Open manual service disconnect
   Don high-voltage insulated gloves. Remove the MSD cover by rotating counterclockwise or releasing locking tabs per manufacturer design. Pull the MSD handle straight out to physically disconnect high-voltage power from the battery pack. Store the MSD in your pocket or secure location to prevent unauthorized reconnection. Insert HV interlock shorting plug if equipped.
   ⚠️Never bypass or defeat the manual service disconnect. This is the primary safety isolation point.
4. 4

   Verify HV system de-energization
   Wait minimum 5 minutes for capacitor discharge. Using a calibrated high-voltage multimeter, verify 0V DC across the main HV bus bars at the Battery Junction Box location. Test between HV positive and HV negative, then each to vehicle ground. Document voltage readings. Only proceed when all readings are below 5V DC.
   ⚠️This verification step is mandatory. Never assume the system is safe based solely on disconnect action.
5. 5

   Raise and support vehicle
   Lift vehicle using manufacturer-specified lift points to working height. Install safety stands rated for vehicle weight plus 50% margin. Verify vehicle stability before working underneath. Remove underbody protective panels covering the battery pack and junction box area.
   ⚠EDV 500 curb weight exceeds 7000 lbs. Ensure lift equipment is properly rated.
6. 6

   Install battery support fixture
   Position the battery support fixture or transmission jack with appropriate adapter beneath the battery pack. Raise fixture until it just contacts the pack without bearing significant weight. This prevents pack movement during junction box removal.
   ℹ️The battery pack is not being removed, only stabilized during junction box service.
7. 7

   Disconnect coolant lines from junction box
   Place drain pans beneath coolant line connections at the Battery Junction Box. Using appropriate line disconnect tools, release the quick-connect fittings on both inlet and outlet coolant lines. Allow EV Battery/Motor Coolant to drain completely into catch containers. Cap or plug open lines to prevent contamination.
   ⚠EV coolant may still be warm. Approximately 1-2 quarts may drain from junction box coolant passages.
8. 8

   Document and disconnect low-voltage connectors
   Photograph all low-voltage connector positions on the Battery Junction Box including sensor connectors, communication harnesses, and monitoring circuits. Label each connector with position identifier. Disconnect all low-voltage connectors by releasing locking tabs and pulling straight back. Secure harnesses away from work area.
   ℹ️Low-voltage connectors may include battery management system sensors, temperature monitors, and CAN communication lines.
9. 9

   Remove HV cable protective covers
   While still wearing HV insulated gloves, remove all protective covers, shields, and guards from high-voltage cables connected to the Battery Junction Box. These are typically orange or marked with HV warning labels. Remove cable management clips and ties documenting original routing.
   ⚠️Even though system is verified de-energized, treat all orange cables as live until physically disconnected.
10. 10

    Disconnect high-voltage cables
    Beginning with the smallest gauge cables and working toward main power cables, disconnect each HV cable from the Battery Junction Box. Remove locking mechanisms (typically sliding locks or threaded collars), then withdraw connectors straight back. Inspect each connector seal and ferrule for damage. Place protective caps on cable ends immediately after disconnection.
    ⚠HV connectors require significant force to disconnect. Support the junction box while pulling to prevent mounting bracket stress.
11. 11

    Remove junction box mounting hardware
    Locate all mounting bolts securing the Battery Junction Box to the battery pack housing (typically 4-8 bolts depending on design). Remove mounting bolts in a cross pattern to prevent warping. Support the junction box weight as final bolts are removed. Carefully lower the junction box assembly and remove from vehicle.
    ℹ️Junction box may weigh 15-30 lbs. Use proper lifting technique or assistant.
12. 12

    Inspect mounting location and prepare new junction box
    Inspect the battery pack mounting surface for corrosion, damage, or coolant leaks. Clean mounting surface with appropriate cleaner. Verify all mounting studs or threaded inserts are intact. Unpack new Battery Junction Box and verify part number matches application. Check that all coolant passages are clear and seals are properly seated.
    ℹ️New junction boxes may come pre-filled with dielectric grease on connectors. Do not remove unless contaminated.
13. 13

    Install new Battery Junction Box
    Position new junction box onto mounting surface, aligning coolant ports and cable entry points. Install mounting bolts finger-tight in cross pattern. Torque mounting bolts to specification in multiple passes (if specs become available; otherwise follow OEM installation guide sequence). Verify junction box is seated flush and does not rock.
    ℹ️Typical junction box mounting torque ranges 20-35 Nm but verify with current Rivian technical data.
14. 14

    Reconnect high-voltage cables
    Remove protective caps from HV cable ends. Inspect connector pins and sockets for any debris or damage. Apply thin coat of dielectric grease to connector seals if not pre-applied. Connect each HV cable to corresponding junction box terminal, ensuring proper alignment before pushing home. Install and lock each connector locking mechanism. Verify each connection is fully seated with no gap between connector body and junction box housing.
    ⚠️Incorrect HV cable routing or connection can cause catastrophic failure. Reference photographs and routing diagrams.
15. 15

    Reconnect coolant and low-voltage systems
    Reconnect coolant quick-connect fittings at junction box inlet and outlet, ensuring audible click indicating full engagement. Reconnect all low-voltage connectors per documentation from disassembly, verifying locking tabs engage. Install all cable ties and routing clips to restore original harness paths. Install HV cable protective covers and shields.
    ℹ️Coolant system will need bleeding after reconnection. Follow separate coolant service procedure.
16. 16

    Reinstall underbody panels and lower vehicle
    Remove battery support fixture. Reinstall all underbody protective panels and fasteners. Lower vehicle from lift and remove safety stands. Verify all tools and equipment are clear of vehicle.
17. 17

    Reconnect 12V battery and restore HV system
    Reconnect 12V battery positive terminal first, then negative terminal. Remove HV interlock shorting plug if installed. Reinstall manual service disconnect (MSD) by pushing firmly until it clicks and locks. Rotate MSD cover to locked position. Remove all warning signs from vehicle.
    ⚠Vehicle systems will initialize when 12V power is restored. Ensure all panels are closed and no one is touching HV components.
18. 18

    Perform system initialization and testing
    Connect diagnostic software and clear service mode. Perform Battery Junction Box initialization procedure per Rivian technical procedures. Run complete high-voltage system integrity check. Monitor for any fault codes related to junction box, HV isolation, or coolant flow. Run thermal management system test cycle to verify coolant circulation through junction box.
    ℹ️Junction box may require software calibration or configuration depending on replacement reason and part design.

Reassembly

1. All reassembly steps are integrated into the main procedure as this repair follows a specific sequence
2. Ensure all HV protective covers are reinstalled - orange cables must never remain exposed
3. Verify coolant system is properly bled and filled to specification using EV Battery/Motor Coolant
4. Confirm all cable routing matches factory configuration using reference photographs
5. Replace any cable ties or clips that were damaged during removal with OEM equivalent parts

Verification

• Connect diagnostic software and verify no HV isolation faults or junction box communication errors are present
• Perform HV isolation resistance test - reading should exceed 500 ohms per volt (minimum 200k ohms for 400V system)
• Verify battery pack voltage is within normal range and balancing correctly across all cell modules
• Test thermal management system - coolant should flow through junction box with no leaks and proper temperature differential
• Perform a controlled test drive with diagnostic monitoring - verify no HV system faults occur under load
• Check that vehicle charge system functions normally and accepts full charge rate without junction box temperature warnings
• Inspect all HV cable connection points for any signs of heat discoloration or arcing after initial operation
• Document repair completion including new junction box part number, software version, and all test results in vehicle service records

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