Brake Booster

This procedure covers the removal and replacement of the electric brake booster assembly on a 2025 Rivian EDV 500, including brake fluid system bleeding and high-voltage safety protocols.

Warnings

Tools required

Parts

• Electric brake booster assembly × 1 — Use OEM Rivian specification
• Brake booster mounting gasket/seal × 1 — Use OEM specification
• Brake line crush washers × 4 — Use OEM specification

Fluids

• DOT 4 Brake Fluid — 1 qt

Preparation

1. Park vehicle on level surface and engage parking brake
2. Ensure high-voltage battery has at least 20% state of charge for system reactivation after repair
3. Open all vehicle doors to prevent lockout when disconnecting 12V battery
4. Disconnect 12V battery negative terminal and wait 2 minutes for system capacitor discharge
5. Access high-voltage service disconnect located under rear seat - remove seat cushion and disconnect per service manual procedure
6. Wait minimum 5 minutes after high-voltage disconnect for capacitor discharge
7. Verify high-voltage system is safe using insulated multimeter - measure DC voltage at HV disconnect should be under 5V
8. Remove driver side lower dashboard trim panels to access brake booster area
9. Place brake fluid catch pan under master cylinder area

Procedure

1. 1

   Disconnect brake pedal linkage
   From inside cabin, locate the brake pedal pushrod connection to the brake booster. Remove the retaining clip and slide the clevis pin out to disconnect the pushrod from the brake pedal arm. Note the orientation and position for reassembly.
2. 2

   Disconnect electrical connectors
   Locate the two electrical connectors on the electric brake booster assembly. The larger connector is the high-voltage power supply (orange conduit), and the smaller is the CAN bus communication connector (black). Press the locking tabs and carefully disconnect both connectors. Cover the high-voltage connector with insulating tape.
3. 3

   Disconnect brake fluid lines from master cylinder
   Using flare nut wrenches to prevent rounding, carefully loosen and disconnect the four brake lines from the integrated master cylinder on the brake booster assembly. Label each line (LF, RF, LR, RR) for proper reconnection. Allow fluid to drain into catch pan. Immediately cap or plug open lines to prevent contamination and further fluid loss.
4. 4

   Remove brake booster mounting nuts
   From the engine bay side of the firewall, locate the four mounting nuts securing the brake booster assembly. These are typically 13mm or 14mm nuts. Support the brake booster assembly from inside the cabin while removing the final nuts to prevent it from falling.
5. 5

   Remove brake booster assembly
   Carefully pull the brake booster assembly straight back through the firewall opening into the cabin area. Maneuver around steering column and other components as needed. Note the position of any spacers, shims, or gaskets on the mounting studs.
6. 6

   Prepare firewall mounting surface
   Clean the firewall mounting surface thoroughly, removing any old gasket material, debris, or corrosion. Inspect mounting studs for damage or thread wear. The mounting surface must be clean and flat for proper sealing.
7. 7

   Install new brake booster gasket
   Position the new brake booster mounting gasket on the firewall studs, ensuring proper orientation. The gasket should sit flush against the firewall with all mounting holes aligned.
8. 8

   Install new brake booster assembly
   Carefully maneuver the new electric brake booster assembly through the cabin and align it with the firewall mounting studs. Push firmly to seat the booster against the gasket. From the engine bay side, install the four mounting nuts finger-tight.
9. 9

   Torque brake booster mounting nuts
   Torque the four mounting nuts in a cross-pattern to ensure even seating. Without manufacturer torque specifications available, use 18-22 ft-lbs as a conservative estimate for this type of assembly. Verify the booster is seated evenly against the firewall with no gaps.
10. 10

    Reconnect brake pedal linkage
    From inside the cabin, align the brake pedal pushrod with the brake pedal arm clevis. Insert the clevis pin and secure with the retaining clip. Verify the pin is fully seated and the clip is properly installed. Check for smooth pedal movement without binding.
11. 11

    Reconnect brake fluid lines
    Install new crush washers on each brake line fitting. Thread each brake line into the correct port on the master cylinder (following your labels: LF, RF, LR, RR). Hand-tighten first to ensure proper thread engagement. Using flare nut wrenches, torque brake line fittings to 11-13 ft-lbs. Do not overtighten as this can damage the flare seats.
12. 12

    Reconnect electrical connectors
    Remove insulating tape from high-voltage connector. Reconnect the CAN bus communication connector (black) first, ensuring the locking tab clicks. Then reconnect the high-voltage power connector (orange conduit), pressing firmly until the locking mechanism engages. Verify both connections are secure.
13. 13

    Fill and bleed brake system
    Fill brake fluid reservoir with fresh DOT 4 brake fluid to the MAX line. Using a pressure or vacuum brake bleeder, bleed all four wheels in the proper sequence (typically RR, LR, RF, LF for this vehicle). Continue bleeding until all air is removed and only clear, bubble-free fluid emerges. Maintain reservoir level throughout bleeding process. Check for leaks at all brake line connections during bleeding.
14. 14

    Reconnect power systems
    Reconnect the high-voltage service disconnect under the rear seat, ensuring proper seating and locking. Reconnect the 12V battery negative terminal. The vehicle will perform self-checks upon power restoration.
15. 15

    Perform system calibration
    Connect Rivian-approved diagnostic scan tool and access brake system module. Perform electric brake booster calibration and initialization procedure per Rivian service software instructions. Clear any fault codes related to the brake booster replacement. Verify all brake system modules communicate properly.

Reassembly

1. Reinstall driver side lower dashboard trim panels, ensuring all clips are properly seated
2. Replace rear seat cushion and verify high-voltage disconnect cover is secure
3. Check brake fluid reservoir level and top off to MAX line with DOT 4 fluid if needed
4. Close all vehicle doors and test door locks, windows, and interior lighting function properly

Verification

• With vehicle in PARK and wheels chocked, start the vehicle and verify no brake warning lights illuminate on the dash
• Press brake pedal and verify firm pedal feel with no excessive travel or sponginess
• Perform multiple brake applications and verify consistent pedal feel and height
• Check all brake line connections for leaks with pedal applied
• Using scan tool, verify no brake system fault codes are present
• Perform low-speed brake test in safe area (5-10 mph) to verify proper brake function and ABS communication
• Test regenerative braking integration by verifying smooth transitions between regen and friction braking
• Verify electronic stability control and traction control systems function properly with scan tool
• Before returning vehicle to service, perform brake test at various speeds in a safe environment to confirm full brake system functionality
• Recommend professional brake system inspection and road test if any abnormal behavior is observed

Related trouble codes on this vehicle

Codes that commonly send this job to the bay — tap one for symptoms, causes, and diagnostic steps.

Chasing one of these codes and not sure which part is guilty? Ask a master mechanic about YOUR car →

More procedures for this vehicle