Replace the brake proportioning valve (load sensing proportioning valve) to restore proper brake force distribution between front and rear brakes.

Warnings

Tools required

Parts

• Brake proportioning valve (load sensing proportioning valve) × 1 — Use OEM Toyota specification
• Brake line crush washers × 4 — Use OEM specification - replace all

Fluids

• DOT 3 Brake Fluid — 1 qt

Preparation

1. Park vehicle on level ground and set parking brake firmly
2. Place wheel chocks behind front wheels
3. Open brake fluid reservoir cap to relieve any vacuum pressure, then close loosely
4. Raise rear of vehicle using floor jack at designated rear lift point
5. Support vehicle securely on jack stands rated for vehicle weight at proper support points
6. Lower vehicle onto jack stands and verify stability before working underneath
7. Locate brake proportioning valve - typically mounted on or near rear axle beam with brake lines connected
8. Clean area around proportioning valve and brake line fittings with brake cleaner to prevent contamination
9. Apply penetrating oil to all brake line fittings and let soak for 10-15 minutes if fittings appear corroded
10. Prepare brake line plugs or caps to immediately seal open brake lines

Procedure

1. 1

   Prepare brake fluid reservoir
   Open the hood and locate the brake fluid reservoir on the master cylinder. Use a turkey baster or fluid evacuation pump to remove as much brake fluid as possible from the reservoir to minimize spillage when lines are disconnected. Dispose of old brake fluid properly. Keep reservoir cap loose but in place.
2. 2

   Disconnect inlet brake line from proportioning valve
   Position drain pan under the proportioning valve. Using the appropriate size flare nut wrench (typically 10mm or 12mm), carefully loosen the inlet brake line fitting that comes from the master cylinder to the proportioning valve. Turn counterclockwise slowly. Once loose, unthread by hand and immediately plug the open brake line with a brake line plug to prevent fluid loss and air entry. Allow valve to drain into pan.
3. 3

   Disconnect outlet brake lines from proportioning valve
   Using flare nut wrench, disconnect the outlet brake lines that run from the proportioning valve to the rear wheel cylinders or calipers. There are typically two outlet lines. Loosen each fitting counterclockwise, unthread by hand, and immediately plug each open line. Keep track of which line connects to which port for proper reassembly.
4. 4

   Remove proportioning valve mounting hardware
   Identify the mounting bolts or bracket that secures the proportioning valve to the vehicle chassis or rear axle beam. Remove the mounting bolts using appropriate socket or wrench. Support the valve during removal to prevent it from falling. Remove the old proportioning valve from the vehicle.
   Torque spec

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

   Inspect and clean mounting location
   Inspect the mounting bracket and surrounding area for damage, corrosion, or debris. Clean mounting surfaces with wire brush if needed. Check that all brake line fittings and threads are clean and free of debris. Inspect brake lines for damage, cracks, or excessive corrosion - replace any questionable brake lines before proceeding.
6. 6

   Install new proportioning valve
   Remove plugs from ports on new proportioning valve. Position new proportioning valve in mounting location, ensuring correct orientation - inlet port should face toward master cylinder direction. Install mounting bolts hand-tight first to ensure proper alignment. Torque mounting bolts to specification using torque wrench.
   Torque spec

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

   Connect inlet brake line
   Remove plug from inlet brake line coming from master cylinder. Install NEW crush washer on the fitting if applicable. Thread the inlet brake line fitting into the proportioning valve inlet port by hand first to ensure proper thread engagement. Once hand-tight, use flare nut wrench and torque wrench to tighten to specification. Do not overtighten - this can damage the flare and cause leaks.
   Torque spec

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

   Connect outlet brake lines
   Remove plugs from outlet brake lines. Install NEW crush washers on fittings if applicable. Connect each outlet brake line to its corresponding port on the proportioning valve (reference notes from disassembly). Thread each fitting by hand first to prevent cross-threading. Once hand-tight, use flare nut wrench and torque wrench to tighten each outlet line fitting to specification.
   Torque spec

   Brake Line Fittings15 Nm (11 lb-ft)
9. 9

   Verify all connections
   Visually inspect all three brake line connections to ensure they are properly seated and torqued. Gently attempt to wiggle each line - there should be no movement at the fittings. Check that the proportioning valve mounting bolts are secure. Wipe away any spilled brake fluid from components and surrounding areas.
10. 10

    Bleed brake system - rear brakes first
    Fill brake fluid reservoir to MAX line with fresh DOT 3 brake fluid. Begin bleeding at the rear brake furthest from master cylinder (typically right rear). Have an assistant pump brake pedal 3-5 times and hold pressure, or use vacuum bleeder. Open bleeder screw 1/4 turn and allow fluid/air to evacuate. Close bleeder screw before pedal reaches floor. Repeat until fluid runs clear with no air bubbles. Torque bleeder screw to specification. Repeat for left rear brake. Maintain reservoir fluid level above MIN throughout bleeding process.
    Torque spec

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

    Bleed brake system - front brakes
    Continue bleeding procedure at right front brake, then left front brake using same technique. Ensure all four wheels are properly bled and fluid runs clear with no air bubbles from any bleeder. Keep brake fluid reservoir topped off during entire bleeding process. Final reservoir level should be at MAX line when complete.
12. 12

    Perform brake pedal test
    With engine off, pump brake pedal firmly multiple times. Pedal should become firm and not sink to floor. If pedal feels soft or spongy, repeat bleeding procedure - air remains in system. Check all brake line connections for any signs of leakage while assistant holds firm pressure on brake pedal. Tighten any weeping fittings slightly if needed, but do not exceed torque specifications.

Reassembly

1. Ensure brake fluid reservoir is filled to MAX line with fresh DOT 3 brake fluid and cap is securely tightened
2. Raise vehicle slightly with floor jack, remove jack stands, and carefully lower vehicle to ground
3. Double-check that all brake line fittings are properly torqued and show no signs of leakage
4. Clean any brake fluid residue from under vehicle and chassis components with water
5. Remove wheel chocks from front wheels

Verification

• With engine running, pump brake pedal several times - it should feel firm and consistent with good resistance
• Perform static brake test: with engine running, apply firm brake pedal pressure for 30 seconds - pedal should not sink or feel spongy
• Check brake fluid reservoir level - should be at MAX line with no bubbles visible in fluid
• Inspect all brake line connections at proportioning valve for any signs of fluid leakage - there should be no wetness or drips
• Perform low-speed brake test in safe area: drive vehicle at 5-10 mph and apply brakes firmly - vehicle should stop smoothly without pulling to either side
• Perform moderate-speed brake test in safe area: drive at 20-25 mph and apply brakes progressively harder - rear brakes should engage properly without premature lockup
• Test parking brake function - should hold vehicle firmly on moderate incline
• If ANY abnormal brake behavior is detected (soft pedal, pulling, noise, warning lights), DO NOT drive vehicle - repeat bleeding procedure or seek professional service
• Monitor brake performance and check for leaks after first 50 miles of driving

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