Brake Booster

This procedure covers removal and replacement of the electric brake booster assembly on the 2024 Rivian EDV 500, including brake fluid line disconnection and system bleeding.

Warnings

Tools required

Parts

• Electric brake booster assembly × 1 — Use OEM Rivian part number
• Brake booster mounting gasket/seal × 1 — Use OEM specification
• Brake line crush washers × 4 — Use OEM specification
• Push rod clevis pin × 1 — Use OEM specification if damaged

Fluids

• DOT 4 Brake Fluid — 1 qt

Preparation

1. Park vehicle on level ground and place in Park mode
2. Chock rear wheels securely
3. Access the 12V battery in the front compartment and disconnect negative terminal first, then positive terminal using battery disconnect tool
4. Wait minimum 5 minutes for vehicle systems to power down completely
5. Remove driver's side lower dash panel and knee bolster to access brake pedal assembly mounting area
6. Place absorbent pads and drain pan under brake master cylinder area to catch fluid
7. Using brake fluid transfer pump or turkey baster, remove as much brake fluid as possible from master cylinder reservoir to minimize spillage
8. Photograph all electrical connector orientations and brake line routing for reference during reassembly

Procedure

1. 1

   Disconnect electrical connectors
   Locate the main electrical connector on the electric brake booster assembly. Depress the locking tab and carefully disconnect the main power connector. Disconnect the secondary sensor connector if equipped. Use multimeter to verify no voltage present on any pins before proceeding.
2. 2

   Disconnect brake pedal push rod
   Working from inside the cabin at the brake pedal assembly, locate the clevis pin connecting the brake booster push rod to the brake pedal arm. Remove the retaining clip using pliers, then extract the clevis pin. Support the push rod to prevent it from falling when disconnected. Note the orientation and any adjustment settings on the push rod.
3. 3

   Disconnect brake lines from master cylinder
   Using appropriate flare nut wrenches, carefully loosen and remove the brake line fittings from the master cylinder ports. Work slowly to avoid rounding the fittings. There are typically four brake lines (one for each wheel circuit). Cap or plug the open brake lines immediately to prevent fluid loss and contamination. Remove and discard the crush washers from each fitting.
   ⚠Brake line fittings are easily damaged. Use proper flare nut wrenches, not standard wrenches or adjustable pliers.
4. 4

   Remove master cylinder from booster
   Locate the two or three mounting bolts securing the master cylinder to the electric brake booster assembly. Remove these bolts and carefully pull the master cylinder straight off the booster to avoid damaging the push rod seal. Set the master cylinder aside in a clean area, keeping it level to minimize additional fluid loss.
5. 5

   Remove brake booster mounting nuts
   From inside the vehicle, locate the mounting nuts securing the brake booster to the firewall (typically four nuts accessible from the pedal assembly area). Support the brake booster from the engine compartment side while removing the final nut. The assembly is heavy (approximately 15-20 lbs) and awkward to handle.
6. 6

   Remove brake booster assembly
   Carefully withdraw the electric brake booster assembly from the firewall, maneuvering it through the engine compartment. You may need to rotate or angle the unit to clear surrounding components. Remove the mounting gasket from the firewall and inspect the firewall mounting surface for damage or corrosion.
7. 7

   Inspect and clean mounting area
   Thoroughly clean the firewall mounting surface, removing any old gasket material, brake fluid residue, or corrosion. Inspect the mounting studs on the firewall for damage and verify they are secure. Clean any brake fluid from surrounding components and wiring harnesses.
8. 8

   Prepare new brake booster
   Unpack the new electric brake booster assembly. Verify part number matches the application. Check that the push rod length and adjustment match the old unit. Install a new mounting gasket onto the booster or firewall per manufacturer specification. Inspect all mounting surfaces and electrical connectors on the new unit.
9. 9

   Install new brake booster
   Carefully position the new electric brake booster assembly to the firewall, guiding the mounting studs through the holes and ensuring the push rod enters the cabin through the firewall opening. Align the unit properly before starting any fasteners. From inside the vehicle, install mounting nuts finger-tight, then tighten in a cross-pattern to ensure even seating. Note: Manufacturer torque specifications not available in database - consult service manual for proper torque values.
10. 10

    Install master cylinder
    Check the master cylinder push rod seal and replace if damaged. Align the master cylinder onto the brake booster, ensuring the push rod enters the master cylinder bore correctly. Install mounting bolts and tighten in a cross-pattern. Note: Manufacturer torque specifications not available in database - consult service manual for proper torque values.
11. 11

    Connect brake lines
    Install new crush washers on each brake line fitting. Carefully thread each brake line into the correct master cylinder port, starting threads by hand to prevent cross-threading. Tighten fittings using flare nut wrenches to manufacturer specification. Verify each line is in the correct port position matching your reference photos.
12. 12

    Reconnect brake pedal push rod
    Working from inside the cabin, align the brake booster push rod with the brake pedal arm. Install the clevis pin through the push rod and pedal arm, ensuring it is fully seated. Install the retaining clip, verifying it is properly secured. Test that the pedal moves freely through its full range without binding.
13. 13

    Reconnect electrical connectors
    Reconnect all electrical connectors to the electric brake booster, ensuring they are fully seated and locking tabs engage properly. Route wiring harnesses as original, securing with any clips that were removed. Verify no wires are pinched or under tension.
14. 14

    Bleed brake system
    Fill the master cylinder reservoir with fresh DOT 4 brake fluid from a sealed container. Using a pressure bleeder or manual bleeding method, bleed all four wheels in the sequence: right rear, left rear, right front, left front. Maintain reservoir fluid level throughout bleeding process. Continue bleeding each wheel until fluid runs clear without air bubbles. This system may require 15-20 minutes of bleeding to remove all air.
    ⚠️Brake system must be completely free of air. Any air in the system will cause reduced braking performance or complete brake failure.
15. 15

    Reconnect 12V battery and initialize system
    Reconnect the 12V battery (positive terminal first, then negative). Power on the vehicle and allow the electric brake booster system to initialize. You may hear pump noise and feel brake pedal movement during initialization - this is normal. Use Rivian diagnostic software or authorized service tool to perform brake booster calibration and verify no fault codes are present. Note: Factory calibration may be required.

Reassembly

1. Reinstall driver's side knee bolster and lower dash panel, ensuring all clips and fasteners are secure
2. Verify brake pedal height and free play are within specification
3. Check all brake line connections for leaks
4. Verify master cylinder reservoir is filled to proper level with DOT 4 brake fluid
5. Ensure all electrical connectors are properly seated and locked
6. Remove all tools and materials from vehicle interior and engine compartment

Verification

• With vehicle powered on, verify brake warning light extinguishes after initialization
• Pump brake pedal several times and verify firm pedal with consistent feel - pedal should not sink to floor
• Start vehicle and verify electric brake booster activates (may hear electric motor/pump sound)
• Perform static brake test: with vehicle in Park on level ground, apply firm brake pressure and verify pedal remains firm for 60 seconds
• Check all brake line connections for leaks while assistant applies brake pressure
• Use Rivian diagnostic tool to verify no brake system fault codes are present
• Perform low-speed test in safe area (under 10 mph) to verify brake response and ABS function
• CRITICAL: Before returning vehicle to service, perform multiple brake applications from 25 mph in a safe area to verify proper operation
• If brake pedal feels soft, spongy, or pedal travel is excessive, DO NOT drive vehicle - repeat bleeding procedure
• Advise owner that new brake booster may require break-in period and to report any abnormal brake feel immediately

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