Brake Proportioning Valve

Replace the brake proportioning valve on a 2023 Rivian EDV 500, which controls brake pressure distribution between front and rear axles in the electric delivery van's hydraulic braking system.

Warnings

Tools required

Parts

• Brake proportioning valve assembly × 1 — Use OEM Rivian specification
• Brake line sealing washers × 4 — Use OEM specification for proportioning valve
• Brake line union seals × 4 — Use OEM specification

Fluids

• DOT 4 Brake Fluid — 1 qt

Preparation

1. Park vehicle on level ground and apply parking brake firmly
2. Place wheel chocks behind rear wheels
3. Turn vehicle off and remove key fob from interior
4. Locate brake proportioning valve - typically mounted to frame rail or near master cylinder under vehicle (consult service manual for exact location)
5. Raise vehicle using appropriate lift points and support securely on jack stands rated for vehicle weight
6. Verify vehicle is stable before working underneath
7. Locate and identify all brake lines connected to proportioning valve
8. Clean area around proportioning valve and brake line connections with wire brush to prevent contamination
9. Apply penetrating oil to brake line fittings and allow to soak for 10-15 minutes
10. Prepare brake fluid catch container and position under work area
11. Have replacement proportioning valve and sealing washers ready
12. Place shop towels around work area to catch brake fluid

Procedure

1. 1

   Relieve brake system residual pressure
   With vehicle off, pump brake pedal 10-15 times until pedal feels firm and no further assist is provided. This depletes any residual vacuum or pressure in the brake system. Verify pedal becomes harder with each pump.
   ⚠Do not start vehicle after this step until repair is complete and system is bled.
2. 2

   Document brake line connections
   Before disconnecting anything, photograph or clearly label each brake line connection to the proportioning valve. Note which line connects to which port (typically: master cylinder input, front axle output, rear axle output, and possibly ABS module connection). Use tape and marker to label lines if necessary.
   ℹ️Incorrect reconnection will cause improper brake force distribution and potential brake failure.
3. 3

   Disconnect first brake line
   Using appropriate flare nut wrench, carefully loosen the first brake line fitting at the proportioning valve. Turn counterclockwise slowly to avoid rounding the fitting. Once loose, position catch container underneath and unthread completely by hand. Cap or plug the open brake line immediately with a clean rubber cap to prevent fluid loss and contamination. Brake fluid will drain from both the line and valve.
   ⚠Use flare nut wrenches only - standard wrenches will round off soft brass fittings.
4. 4

   Disconnect remaining brake lines
   Repeat the disconnection process for each remaining brake line connected to the proportioning valve. Work carefully to prevent stripping fittings. Cap each line as it is disconnected. Keep track of any different sized fittings or washers. Note the condition of sealing washers - these must be replaced.
   ⚠Brake fluid will continue to drain. Keep catch container positioned to prevent environmental contamination.
5. 5

   Remove proportioning valve mounting hardware
   Locate and remove the bolts or clips securing the proportioning valve to its mounting bracket or frame rail. Typically secured with 2-3 bolts or a mounting clamp. Support the valve while removing the last fastener to prevent it from falling. Note orientation and position of any mounting brackets or spacers for reinstallation.
6. 6

   Remove old proportioning valve
   Carefully remove the old proportioning valve from the vehicle. Inspect mounting area for corrosion, damage, or brake fluid accumulation. Clean mounting surface thoroughly with brake cleaner and shop towels. Inspect all brake lines for damage, corrosion, or cracks - replace any questionable lines before proceeding.
7. 7

   Prepare new proportioning valve
   Unpack new proportioning valve and verify it matches the old unit in terms of port configuration and mounting points. Install new sealing washers on each port. Do not reuse old washers. Verify all ports are clean and free of debris. Check that all threaded ports are undamaged.
   ℹ️Some proportioning valves come pre-adjusted; others may require adjustment. Verify with manufacturer specifications.
8. 8

   Install new proportioning valve
   Position the new proportioning valve in the mounting location, ensuring proper orientation matches the original installation. Install mounting bolts or clamp and hand-tighten. Verify valve is positioned to allow easy access to all brake line connections. Without torque specifications available, tighten mounting hardware firmly but do not over-torque aluminum or steel brackets.
9. 9

   Reconnect brake lines
   Remove caps from brake lines. Thread each brake line into the correct port on the new proportioning valve by hand first to prevent cross-threading. Ensure new sealing washers are in place. Once hand-tight, use flare nut wrench to snug each fitting. Tighten to approximately 10-12 ft-lbs if using a torque wrench (typical for 3/16" brake lines), or firmly snug by hand wrench if no specification available. Do not over-tighten as this can damage fittings.
   ⚠Cross-threading brake line fittings will cause leaks and require line replacement. Thread carefully by hand first.
10. 10

    Verify all connections
    Double-check that all brake lines are connected to the correct ports per your documentation from Step 2. Verify each fitting is snug and properly seated. Inspect for any signs of cross-threading or improper installation. Ensure no brake lines are kinked, twisted, or in contact with sharp edges or heat sources.
11. 11

    Fill brake fluid reservoir
    Lower vehicle temporarily or access master cylinder reservoir from above. Remove reservoir cap and fill with fresh DOT 4 brake fluid from a sealed container to the MAX line. Keep reservoir filled throughout the bleeding process to prevent air introduction.
    ⚠Never allow brake fluid reservoir to run empty during bleeding - this introduces air into the ABS module requiring specialized bleeding procedures.
12. 12

    Bleed brake system
    Bleed the brake system in the following order: right rear, left rear, right front, left front. Use pressure bleeder or two-person manual bleeding method. At each wheel, attach bleeder hose to bleeder valve, open valve 1/4 turn, allow fluid to flow until clear and bubble-free, then close valve. Repeat for each wheel. For vehicles with ABS, perform additional ABS module bleeding if equipped with Rivian diagnostic tool by cycling ABS valves through scan tool function.
    ⚠️Incomplete bleeding leaves air in the system causing brake failure. Continue bleeding until absolutely no air bubbles appear and pedal is firm.
13. 13

    Inspect for leaks
    With vehicle still raised, closely inspect all connections at the proportioning valve for brake fluid leaks. Have an assistant press the brake pedal firmly and hold while you inspect. Look for any seepage around fittings. If any leaks are found, release pedal pressure, tighten the leaking fitting slightly, and retest. Clean any spilled brake fluid with water and shop towels.
    ⚠️Any leak in the brake system is a critical safety issue. Do not operate vehicle if leaks are present.
14. 14

    Lower vehicle and test brake pedal
    Carefully lower vehicle from jack stands. With vehicle still in park and parking brake engaged, pump brake pedal several times. Pedal should become firm and hold pressure. If pedal sinks slowly or feels spongy, additional bleeding is required. Top off brake fluid reservoir to MAX line as needed after bleeding is complete.

Reassembly

1. Ensure brake fluid reservoir is filled to MAX line with fresh DOT 4 fluid
2. Verify all brake line connections are tight and leak-free
3. Clean any brake fluid residue from painted surfaces, frame, and components with water
4. Remove all tools, containers, and equipment from under vehicle
5. Dispose of old brake fluid and contaminated materials properly according to local regulations
6. If ABS or brake warning lights illuminate, clear codes with scan tool only after verifying system integrity

Verification

• With vehicle in park on level ground, press brake pedal firmly - it should feel solid and not sink
• Start vehicle and verify brake warning light extinguishes after system check
• Check brake fluid level is at MAX line with cap removed
• Perform final visual inspection of all connections at proportioning valve for any seepage
• Perform low-speed brake test in safe area: at 5-10 mph, apply brakes firmly - vehicle should stop straight without pulling to either side
• Perform moderate brake test at 20-25 mph in safe area - brakes should engage smoothly and evenly
• Monitor brake pedal feel over first 50 miles of driving - any changes in pedal firmness or stopping power require immediate inspection
• Recheck all connections and fluid level after 50-100 miles of driving
• If vehicle exhibits any abnormal brake behavior, uneven braking, warning lights, or soft pedal, do not drive and seek professional diagnosis 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