Brake Booster

This procedure covers the removal and replacement of the electric brake booster on a 2022 Rivian EDV 500 commercial van, including brake system bleeding and verification.

Warnings

Tools required

Parts

• Electric brake booster assembly × 1 — Use OEM specification
• Brake booster mounting gasket/seal × 1 — Use OEM specification
• Push rod bushing × 1 — Use OEM specification

Fluids

• DOT 4 Brake Fluid — 1 qt

Preparation

1. Park vehicle on level ground and engage parking brake
2. Chock rear wheels securely
3. Ensure high voltage system is in service mode following Rivian's HV lockout/tagout procedures
4. Disconnect 12V battery negative terminal and wait minimum 5 minutes for airbag system capacitor discharge
5. Remove driver's side floor mat and protect interior with absorbent floor covering
6. Place catch pan under master cylinder area to collect brake fluid
7. Have fresh DOT 4 brake fluid and all replacement parts ready before beginning
8. Connect Rivian diagnostic tool and verify communication with all brake system modules

Procedure

1. 1

   Remove lower dash panel and knee bolster
   From inside the vehicle, remove the lower dash panel below the steering column by removing the retaining clips and screws. Remove the knee bolster panel to access the brake pedal assembly. This provides access to the brake booster push rod connection at the brake pedal.
2. 2

   Disconnect brake pedal from booster push rod
   Locate the push rod connection at the top of the brake pedal assembly. Remove the retaining clip or pin securing the push rod to the brake pedal arm. Carefully disconnect the push rod from the pedal. Note the orientation and position of any spacers or bushings for reinstallation.
3. 3

   Access brake booster in engine compartment
   Open the hood and locate the brake booster assembly on the firewall (driver's side in most configurations). Remove any plastic cowl covers, wiring harnesses, or components blocking access to the brake booster. Document or photograph electrical connector positions before disconnection.
4. 4

   Disconnect electrical connectors from brake booster
   Locate all electrical connectors to the electric brake booster assembly (typically 2-3 connectors). Press the release tabs and carefully disconnect each connector. On Rivian electric boosters, these include the power supply connector, pressure sensor connector, and control module connector. Use electrical connector removal tools if needed to avoid damage.
   ⚠Do not pull on wires. Use only the connector housings to disconnect. Damaged connectors can cause brake system malfunctions.
5. 5

   Mark and disconnect brake lines from master cylinder
   Using a marker or tape, clearly label each brake line connection at the master cylinder (typically 4 lines: left front, right front, left rear, right rear). Using brake line flare nut wrenches to prevent rounding, carefully loosen and remove each brake line connection. Immediately cap or plug each line and port to prevent fluid loss and contamination. Have catch pan ready for fluid spillage.
   ⚠️Brake fluid will drain from lines and master cylinder. Keep fluid away from painted surfaces and eyes.
6. 6

   Remove brake booster mounting nuts
   From the engine compartment side, locate the brake booster mounting nuts (typically 4 nuts) that secure the booster to the firewall. Support the booster unit with one hand while removing the mounting nuts. The booster assembly with integrated master cylinder is heavy (approximately 15-20 lbs), so maintain control during removal.
7. 7

   Remove brake booster assembly
   Carefully pull the brake booster assembly away from the firewall, guiding the push rod through the firewall opening from inside the vehicle. Remove the assembly from the engine compartment. Be careful not to damage any remaining wiring or brake lines in the area. Inspect the firewall mounting surface and clean any debris or old gasket material.
8. 8

   Prepare new brake booster for installation
   Unpack the new electric brake booster assembly and verify it matches the removed unit. Install the new mounting gasket/seal onto the booster or firewall mounting surface as specified. If the push rod bushing is replaceable, install a new bushing onto the push rod. Verify the push rod length matches the original unit (critical for proper brake pedal height and operation).
   ⚠Push rod length is critical. Incorrect length will cause improper brake pedal position and potential brake drag or insufficient braking force. Verify specifications with Rivian documentation.
9. 9

   Install new brake booster assembly
   Guide the push rod through the firewall opening, aligning the mounting studs with the firewall holes. From the engine compartment, push the booster assembly firmly against the firewall ensuring the gasket seats properly. Install mounting nuts finger-tight, then tighten in a crossing pattern to ensure even seating. Since no torque specifications are provided in the database, tighten nuts firmly and evenly until the booster is securely mounted without deforming the firewall or booster mounting flange.
10. 10

    Reconnect brake pedal to push rod
    From inside the vehicle, align the brake pedal arm with the push rod connection point. Install any spacers or bushings in their original orientation. Connect the push rod to the pedal arm and secure with the retaining clip or pin. Verify the connection is secure and the push rod moves freely with pedal movement.
11. 11

    Reconnect brake lines to master cylinder
    Remove caps/plugs from brake lines and master cylinder ports. Reconnect each brake line to its corresponding master cylinder port according to your labels from Step 5. Start threads carefully by hand to avoid cross-threading. Using flare nut wrenches, tighten each connection firmly until secure. Do not overtighten as this may damage the fitting.
12. 12

    Reconnect electrical connectors
    Reconnect all electrical connectors to the brake booster assembly in their original positions. Ensure each connector clicks into place and the locking tab engages fully. Verify no wires are pinched or stressed. Route wiring harnesses as originally positioned.
13. 13

    Bleed brake system
    Reconnect the 12V battery and turn the ignition to ON position (do not start vehicle). Using Rivian diagnostic software, initialize the brake system if required. Fill the master cylinder reservoir with fresh DOT 4 brake fluid. Bleed the brake system starting with the wheel furthest from the master cylinder (typically right rear, left rear, right front, left front) using a pressure bleeder or two-person manual bleeding method. Continue bleeding each wheel until clear, bubble-free fluid flows. The electric booster may require activation through diagnostic software during bleeding.
    ⚠️Maintain proper fluid level in reservoir during bleeding. Never allow reservoir to run dry or air will enter the system requiring complete re-bleeding.
    ⚠For electric brake boosters, follow Rivian-specific bleeding procedures. The booster pump may need to cycle during bleeding to purge all air from the system.
14. 14

    Perform system calibration and testing
    Using Rivian diagnostic software, perform brake system pressure sensor calibration and relearning procedures. Clear any fault codes related to brake booster replacement. Verify all brake system parameters are within specification. Test brake pedal feel with vehicle stationary - pedal should be firm with moderate pressure and not sink to floor.
15. 15

    Reinstall interior and exterior panels
    Reinstall the knee bolster, lower dash panel, and any engine compartment covers removed during disassembly. Verify all clips and fasteners are properly secured. Check that no tools or parts were left in the vehicle.

Reassembly

1. All brake line connections must be tight and leak-free
2. All electrical connectors must be fully seated with locking tabs engaged
3. Interior panels must be properly reinstalled to prevent interference with brake pedal operation
4. Master cylinder reservoir must be filled to MAX line with DOT 4 brake fluid

Verification

• With vehicle stationary and engine in accessory mode, press brake pedal firmly - pedal should be firm and not sink to floor over 30 seconds
• Using diagnostic software, verify no active brake system fault codes are present
• Verify brake warning lights illuminate during key-on self-test and then extinguish
• Check all brake line connections for leaks with pedal pressure applied
• Inspect under master cylinder and at all brake line connections for any brake fluid seepage
• Perform low-speed brake test in safe area - brakes should apply smoothly and evenly with normal pedal effort
• Test brake pedal height - should be at normal position relative to accelerator pedal
• Verify electric brake booster operation by listening for pump activation when applying brakes (slight whirring sound is normal)
• After initial test drive, recheck all brake line connections for leaks and verify proper brake pedal feel
• Have vehicle professionally inspected and test-driven before returning to normal service - brake failure can be fatal

Related trouble codes on this vehicle

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