Pyrotechnic Fuse Inspection

Inspection of the high-voltage pyrotechnic fuse assembly that disconnects the battery pack in emergency conditions, ensuring proper connection integrity and absence of corrosion or damage.

Warnings

Tools required

Parts

• Pyrotechnic fuse assembly (if replacement needed) × 1 — Use OEM specification
• High-voltage connector seals × 2 — Use OEM specification
• Dielectric grease × 1 — Use OEM specification
• Service disconnect plug cover × 1 — Use OEM specification

Preparation

1. Verify technician is certified for high-voltage vehicle work and trained on Rivian EDV systems
2. Ensure vehicle has been sitting for at least 2 hours with HVAC off to allow high-voltage components to cool
3. Verify battery state of charge is below 30% using diagnostic tool
4. Park vehicle on level surface and engage parking brake
5. Place wheel chocks front and rear
6. Disconnect 12V auxiliary battery negative terminal and wait 2 minutes
7. Place high-voltage safety lockout tag on steering wheel
8. Don high-voltage safety gloves and verify integrity (no tears or damage)
9. Review vehicle-specific pyrotechnic fuse location in service manual (typically at battery pack positive terminal)
10. Ensure fire extinguisher rated for electrical fires is immediately accessible

Procedure

1. 1

   Access High-Voltage Service Disconnect
   Remove cargo area rear panel to access the high-voltage service disconnect located beneath the load floor. Use trim tools to carefully release panel clips without damaging surrounding components. Remove service disconnect cover by rotating counterclockwise.
2. 2

   Remove High-Voltage Service Disconnect Plug
   Wearing high-voltage gloves, grasp the orange high-voltage service disconnect plug handle and pull straight out with firm, steady pressure. The plug will audibly click when fully disengaged. Place the plug in a secure location away from the vehicle and attach safety lockout tag.
3. 3

   Verify High-Voltage Isolation
   Wait 15 minutes for high-voltage system capacitors to discharge. Using CAT III voltage detector, verify no voltage is present at the service disconnect terminals. Document voltage readings in service records. Verify diagnostic tool confirms high-voltage system is isolated.
4. 4

   Remove Battery Pack Access Panel
   Remove fasteners securing the battery pack upper access panel located in the cargo area. Lift panel carefully and support to prevent damage. This provides access to the pyrotechnic fuse assembly mounted on the positive battery pack terminal.
5. 5

   Document Pre-Inspection Condition
   Using diagnostic scan tool, retrieve and document any stored fault codes related to high-voltage system, pyrotechnic fuse circuit, or battery management system. Take photographs of pyrotechnic fuse assembly from multiple angles showing overall condition and connector orientation.
6. 6

   Visual Inspection of Pyrotechnic Fuse Assembly
   Carefully inspect pyrotechnic fuse housing for any signs of physical damage, cracks, burns, discoloration, or deformation. Check for evidence of arcing, melting, or thermal damage. Inspect mounting points for secure attachment. Any damage observed requires immediate component replacement and investigation.
7. 7

   Inspect High-Voltage Connections
   Examine both the input and output high-voltage terminal connections to the pyrotechnic fuse. Check for corrosion, discoloration, looseness, or contamination. Verify orange high-voltage cable insulation shows no signs of cracking, melting, or exposure of conductors. Check cable routing for proper clearance and secure retention.
8. 8

   Inspect Control Circuit Connectors
   Locate the small control circuit connector on the pyrotechnic fuse assembly (typically a 2-3 pin connector). Verify connector lock is fully engaged. Check connector housing for damage and pins for corrosion or bent contacts. Verify wiring harness has proper strain relief and no signs of chafing.
9. 9

   Measure Continuity and Resistance
   Using high-voltage capable multimeter with vehicle still isolated, measure continuity across pyrotechnic fuse main terminals. Reading should indicate continuity (typically less than 0.1 ohms). Measure resistance of pyrotechnic firing circuit per service manual specifications (typically 1-3 ohms). Document all readings.
10. 10

    Inspect Seals and Environmental Protection
    Check all environmental seals around pyrotechnic fuse housing and connectors for proper seating, damage, or degradation. Verify breather vents (if equipped) are clear and functioning. Check for any evidence of moisture intrusion in connector cavities or on terminals.
11. 11

    Thermal Inspection
    If thermal imaging camera is available, inspect pyrotechnic fuse assembly and surrounding connections for any evidence of previous thermal anomalies or hot spots (appears as discoloration pattern). This can indicate poor connections or excessive current flow during vehicle operation.
12. 12

    Diagnostic System Verification
    With diagnostic tool connected, verify battery management system reports proper pyrotechnic fuse status and continuity. Check that firing circuit resistance values are within specification range. Verify no isolation faults or unexpected voltage readings are present in system monitoring data.
13. 13

    Service and Clean Connections
    If inspection reveals minor corrosion or contamination on terminals (but component is otherwise serviceable), carefully clean using approved electrical contact cleaner and lint-free cloth. Apply thin layer of dielectric grease to connection points per service manual specifications. Do not apply excessive grease which can attract contaminants.
14. 14

    Reinstall Access Panels
    Reinstall battery pack access panel and secure with all fasteners. Ensure proper torque is applied and no tools or parts remain in battery compartment. Verify all panel seals are properly seated to maintain environmental protection of high-voltage components.
15. 15

    Restore High-Voltage System
    Remove safety lockout tag from service disconnect plug. Wearing high-voltage gloves, align service disconnect plug with receptacle and push firmly until audible click confirms full engagement. Install service disconnect cover by rotating clockwise. Reconnect 12V auxiliary battery. Remove safety lockout tag from steering wheel.

Reassembly

1. Ensure all access panels are properly secured and sealed
2. Verify service disconnect is fully engaged and cover is installed
3. Confirm no tools, parts, or materials remain in battery compartment
4. Replace any damaged seals or covers identified during inspection
5. Apply dielectric grease to cleaned connection points as specified

Verification

• Power on vehicle and verify no high-voltage system fault codes are present
• Using diagnostic tool, verify battery management system recognizes pyrotechnic fuse circuit integrity
• Confirm high-voltage system voltage and current measurements are within normal parameters
• Verify READY indicator illuminates normally and vehicle can be placed in drive mode
• Test drive vehicle briefly to confirm normal operation and monitor for any high-voltage system warnings
• Perform final scan for diagnostic trouble codes and document inspection results in vehicle service records
• Complete high-voltage work verification checklist per shop safety protocols

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