This procedure replaces the brake proportioning valve, which regulates brake pressure distribution between front and rear axles to ensure balanced braking performance.

Warnings

Tools required

Parts

• Brake proportioning valve assembly × 1 — Use OEM specification
• Brake line copper washers (if applicable) × 4 — Use OEM specification
• DOT 4 brake fluid × 1 — Use OEM specification

Fluids

• DOT 4 Brake Fluid — 1 qt

Preparation

1. Park vehicle on level surface and engage parking brake firmly
2. Place wheel chocks behind rear wheels
3. Open hood and locate brake fluid reservoir on master cylinder
4. Use turkey baster or fluid transfer pump to remove brake fluid from reservoir to below MAX line to prevent overflow during work
5. Locate proportioning valve assembly (typically mounted on firewall near master cylinder or on frame rail)
6. Spray all brake line fittings at proportioning valve with penetrating oil and allow 15 minutes to soak
7. Gather all tools, new parts, and fresh brake fluid before beginning
8. Have brake line plugs ready to immediately cap open lines

Procedure

1. 1

   Label and photograph brake line connections
   Before disconnecting anything, take clear photos of all brake line connections to the proportioning valve from multiple angles. Use masking tape to label each brake line (e.g., 'LF' for left front, 'RR' for right rear, 'Master' for input from master cylinder). Note the orientation of the valve body for correct reinstallation.
2. 2

   Disconnect first brake line from proportioning valve
   Using the appropriate size flare nut wrench (typically 10mm or 12mm), carefully loosen the first brake line fitting at the proportioning valve. Hold the valve body steady with another wrench if necessary to prevent twisting. Once loose, unthread the fitting by hand. Immediately plug the open brake line with a brake line plug or cap to prevent fluid loss and contamination. Allow fluid to drain into catch pan.
   ⚠Use only flare nut wrenches on brake line fittings. Standard wrenches will round off the soft brass fittings, requiring brake line replacement.
3. 3

   Disconnect remaining brake lines
   Repeat the process for all remaining brake lines connected to the proportioning valve (typically 3-5 lines total). Work methodically, plugging each line immediately after disconnection. Keep track of which line came from which port using your labels and photos. Minimize brake fluid spillage by having rags ready.
4. 4

   Remove proportioning valve mounting bolts
   Remove the bolts securing the proportioning valve to its mounting bracket or firewall. These are typically 10mm or 12mm bolts. Support the valve with one hand as you remove the last bolt to prevent it from falling. Remove the valve from the vehicle.
   ℹ️Note the position of any spacers, washers, or brackets for correct reassembly.
   Torque spec

   Proportioning Valve Bolts15 Nm (11 lb-ft)
5. 5

   Prepare new proportioning valve
   Unpack the new proportioning valve and verify it matches the old unit exactly (same number and position of ports). If the valve includes integrated brackets or mounting hardware, ensure they match your application. Clean the mounting surface on the firewall or bracket with a wire brush and clean rag. Inspect all brake line fitting threads for damage or debris.
6. 6

   Install new proportioning valve
   Position the new proportioning valve in the correct orientation (reference your photos). Start all mounting bolts by hand to ensure proper thread engagement. Tighten bolts to specification using a torque wrench. Ensure the valve is secure and properly oriented with ports accessible for brake line connection.
   Torque spec

   Proportioning Valve Bolts15 Nm (11 lb-ft)
7. 7

   Connect brake lines to new valve
   Remove plugs from brake lines one at a time. If copper crush washers are used at the fittings, install new washers (do not reuse old washers). Thread each brake line fitting into the correct port by hand first, ensuring at least 3-4 full turns before using a wrench. This prevents cross-threading. Reference your labels and photos to ensure each line goes to the correct port. Once all fittings are hand-tight, use a flare nut wrench and torque wrench to tighten to specification.
   ⚠️Incorrect brake line routing will cause improper brake balance and potential loss of braking on one or more wheels. Double-check all connections against your photos before proceeding.
   Torque spec

   Brake Line Fittings15 Nm (11 lb-ft)
8. 8

   Refill brake fluid reservoir
   Fill the brake fluid reservoir with fresh DOT 4 brake fluid to the MAX line. Use only brake fluid from a sealed container that has been opened immediately before use. Contaminated or moisture-absorbed fluid will cause brake system damage.
9. 9

   Bleed brake system - rear brakes
   Bleed the brake system starting with the wheel furthest from the master cylinder (typically right rear). Attach bleeder hose to bleeder screw and submerge other end in clean brake fluid in a clear container. Have an assistant pump brake pedal 3-4 times and hold pressure, then open bleeder screw 1/4 turn. Close bleeder screw before pedal reaches floor. Repeat until no air bubbles appear in discharged fluid. Tighten bleeder screw to specification. Repeat for left rear brake. Check reservoir level frequently and maintain above MIN line at all times.
   ⚠️Never let brake fluid reservoir run dry during bleeding. If reservoir empties, air will enter ABS hydraulic unit requiring dealer scan tool to bleed.
   Torque spec

   Bleeder Screw14 Nm (10 lb-ft)
10. 10

    Bleed brake system - front brakes
    Continue bleeding process at right front brake, then left front brake, using same procedure as rear brakes. Ensure firm pedal feel is achieved with no air bubbles in discharged fluid from any wheel. Top off brake fluid reservoir to MAX line when complete.
    Torque spec

    Bleeder Screw14 Nm (10 lb-ft)
11. 11

    Inspect for leaks
    With brake system bled, have assistant apply firm brake pedal pressure (approximately 50 lbs) and hold for 30 seconds. Carefully inspect every brake line connection at the proportioning valve for any signs of fluid seepage or drips. Check mounting bolts for tightness. Wipe all connections dry and repeat pressure test. No leaks are acceptable.
    ⚠️Any brake fluid leak, no matter how small, is a complete failure. Do not operate vehicle until leak is corrected.

Reassembly

1. Verify all brake line fittings are torqued to specification using flare nut wrenches
2. Verify proportioning valve mounting bolts are torqued to specification
3. Top off brake fluid reservoir to MAX line with fresh DOT 4 fluid
4. Clean any spilled brake fluid from painted surfaces immediately with water
5. Double-check all connections against reference photos taken during disassembly

Verification

• With engine off, pump brake pedal several times - pedal should be firm and not sink to floor
• Start engine (power brake assist should activate) - pedal should remain firm with no excessive travel
• Perform static leak test: apply firm pedal pressure for 60 seconds, inspect all connections for leaks
• Test drive in safe area at low speed (under 15 mph): verify brakes engage smoothly without pulling to either side
• Perform gradual brake applications at 25-30 mph: verify balanced braking with no unusual sounds or pedal pulsation
• Perform moderate brake application from 40 mph in safe area: verify vehicle stops straight with firm pedal feel and no ABS activation on dry pavement
• Recheck brake fluid level after test drive and top off if needed
• Final visual inspection of all proportioning valve connections for any signs of seepage after test drive
• If any abnormal pedal feel, pulling, noise, or leaks occur, do not operate vehicle - repeat bleeding procedure or seek professional assistance

More procedures for this vehicle