2003 Toyota 4RUNNER Parking Brake Problems and Adjustment

By Core Brake Parts Tech Team — Circleville, OH warehouse

The 2003 Toyota 4Runner uses a foot-operated parking brake that works a small set of brake shoes inside the hat of each rear disc rotor. When the pedal needs too many clicks to hold, or the truck rolls on a grade, the fix is almost always a shoe adjustment followed by a cable adjustment, and the shoes themselves only need replacing when the lining is worn to its limit or contaminated.

This guide explains how the system is built on the 2003 4Runner, what the common parking brake problems look like, how the adjustment is done, and when parts need to be replaced instead.

How the 2003 4Runner Parking Brake Works

The 2003 model year was the first of the fourth-generation 4Runner, and Toyota's owner's manual for it states plainly that the vehicle has a drum-in-disc type parking brake system. The rear service brakes are discs with calipers and pads. The parking brake is a separate mechanism: two small shoes mounted on the rear backing plate sit inside the drum surface machined into the center hat of each rear rotor.

When you push the parking brake pedal to the left of the brake pedal, a cable pulls a lever on each rear shoe set. The lever spreads the shoes against the inside of the rotor hat and locks the wheel. Pressing the pedal a second time releases it. The rear calipers play no part in holding the truck once it is parked.

Two details matter for anyone working on it:

• The shoes do not adjust themselves. In the 4Runner's service procedure, shoe clearance is set by hand with a star-wheel adjuster reached through a hole in the rotor face. As the linings wear, pedal travel grows until someone readjusts it.
• Toyota calls for bedding-down. The owner's manual says this type of system needs bedding-down of the shoes periodically, and whenever the shoes or drums (the rotors) are replaced. New shoes that are never bedded hold poorly at first.

Common Parking Brake Problems and Their Causes

The warning light deserves a closer look. On the 2003 4Runner the same red brake system warning light comes on when the parking brake is applied, when the brake fluid level is low, and when the hydraulic brake booster has a fault. Toyota's manual tells owners to stop and contact a dealer if the light does not turn off after the parking brake is released. Do not assume a lit light is only the parking brake until you have confirmed the fluid level and that the pedal is fully released.

Cold climates add one more cause. Toyota specifically warns against setting the parking brake when it could freeze, because snow or water around the mechanism can freeze and make it hard to release. In freezing weather the manual recommends putting the transmission in Park and blocking the wheels instead.

Checking the Parking Brake Before You Adjust Anything

Start with the simple test from Toyota's own maintenance list: on a safe incline, the vehicle should be held securely with only the parking brake applied, and the pedal should have the proper travel.

To measure travel, fully depress the pedal to set it, depress it again to release it, then press it slowly with firm, steady force while counting the clicks. The 2003 4Runner owner's manual specification is 5 to 7 clicks when depressed with a force of 294 N (30 kgf, 66.1 lbf). More clicks than that means the system needs adjustment. Fewer than that can mean the shoes are set too tight and may drag.

Next, raise the rear of the truck safely on stands with the parking brake released and spin each rear wheel by hand. A wheel that drags with the pedal fully released points to a sticking cable, a seized lever, or shoes set too tight, and that has to be fixed before any adjustment will hold.

How the Adjustment Is Done

The 4Runner service procedure adjusts the system in two stages, and the order matters: shoes first, cable second. Adjusting only the cable to take up worn shoes uses up cable travel and can leave the shoes lightly applied all the time.

1. Release the cable. Remove the lower instrument panel finish panel to reach the pedal-end cable adjuster, fully release the pedal, and back off the lock nut and adjusting nut so the cable is slack.
2. Set shoe clearance at each rear wheel. Remove the rear wheel and hold the rotor in place with a couple of lug nuts. Through the adjustment hole in the rotor face, turn the star-wheel adjuster to expand the shoes until the rotor locks. Then turn it the other way until the rotor rotates smoothly, backing off the number of notches given in the factory service manual for your truck.
3. Take up the cable. Turn the cable adjusting nut until pedal travel falls inside the 5 to 7 click range, hold the adjusting nut with a wrench, and tighten the lock nut to the factory torque value.
4. Verify. Work the pedal several times, recheck the click count, confirm the parking brake warning light comes on at the first click, and confirm both rear wheels spin freely when released.

If the shoes are new, or the truck still will not hold on a grade after a correct adjustment, the shoes need the bedding-down procedure Toyota specifies. It is a controlled, light drag of the parking brake at low speed with cool-down intervals. Follow the service manual procedure exactly, or have a shop do it. Skipping it is a common reason a freshly rebuilt parking brake still lets the truck roll.

When Adjustment Is Not Enough: Parts to Replace

Pull the rear rotors and inspect the parking brake hardware when the brake will not hold after adjustment, when a wheel drags, or any time the rear rotors are being replaced anyway. The owner's manual lists a lining wear limit of 1.0 mm (0.04 in.) for the brake linings. Replace the shoes if they are at or below that limit, cracked, glazed, or soaked with oil or grease. On a 4WD truck, a leaking rear axle seal is a classic source of contamination on the rear shoes, so fix the leak before installing new linings.

Also check:

• The drum surface inside the rotor hat. Rust ridges or scoring here hurt holding power as much as worn shoes. If you are buying new rear brake rotors, the parking brake drum comes with them.
• Springs, hold-downs, the strut and the adjuster screw. Return springs weaken with heat and rust, and a seized adjuster cannot be set. A fresh brake hardware kit is cheap insurance when the shoes are out.
• The cables. A cable that is frayed, kinked or rusted inside its housing will not release cleanly no matter how well the shoes are adjusted.

During reassembly, the 4Runner service manual calls for high-temperature grease on the backing plate contact points, the shoe lever contact points, and the adjusting screw set, and it warns that no oil or grease may touch the shoe linings or the drum surface. Clean your hands and the rotor hat before final assembly.

Replacement parking brake shoes are the core part for this job. Since the rotors come off to reach them, it is the natural time to inspect the rear pads too; if they are close to their limit, matching brake pads save a second teardown.

How Hard Is This Job?

Checking click count and adjusting the shoes through the rotor face is a moderate driveway job: jack stands, a brake adjusting tool or flat screwdriver, and patience. Replacing the shoes is harder. The rear caliper and rotor must come off, the shoe springs are stiff, and the cable has to be connected to the shoe lever on the backing plate. The bedding-down step afterward is easy to skip and should not be.

Recall check: an NHTSA recall lookup for the 2003 4Runner lists campaigns for accelerator pedal floor-mat entrapment, a fuel pulsation damper, and alloy wheels, but no parking brake recall. Parking brake problems on this truck are wear and maintenance items, not a known defect.

While you are under there, check the brake fluid as well. Toyota specifies SAE J1703 or FMVSS No. 116 DOT 3 brake fluid for the 2003 4Runner.

Frequently Asked Questions

Does the 2003 4Runner have rear drum brakes?

No. The rear service brakes are discs. The only drum on the rear is the small parking brake drum machined into the inside of each rear rotor hat, which Toyota calls a drum-in-disc parking brake.

How many clicks should the 2003 4Runner parking brake take?

Toyota's owner's manual specifies 5 to 7 clicks with the pedal pressed at a force of 294 N (about 66 lbf). More clicks means the shoes and cable need adjustment.

Does the parking brake adjust itself when I back up or use it?

No. On this design the shoe clearance is set manually with a star-wheel adjuster through the rotor face, so it needs periodic adjustment as the linings wear.

Why will my parking brake not hold after I installed new shoes?

New shoes usually need the bedding-down procedure Toyota specifies before they reach full holding power. Also confirm the shoes were adjusted before the cable, and that no grease reached the linings or drum surface.

Should I replace the parking brake shoes when I replace the rear rotors?

Inspect them every time the rotors come off. Replace them if the lining is near the 1.0 mm wear limit, contaminated, or glazed, and adjust and bed them against the new rotor drums either way.

Sources

1. Toyota 2003 4Runner Owner's Manual (OM35820U) - drum-in-disc parking brake, bedding-down requirement, 5 to 7 clicks at 294 N, 1.0 mm lining wear limit, warning light behavior, freezing warning, DOT 3 fluid
2. Toyota 4Runner Service Manual - Parking Brake System Adjustment - shoe-then-cable adjustment procedure, adjuster through the rotor, lock nut, warning light check
3. Toyota 4Runner Service Manual - Parking Brake Assembly Reassembly - component layout, high-temperature grease points, no grease on linings or drum
4. NHTSA Recalls API - 2003 Toyota 4Runner - recall campaigns on file; none for the parking brake