POWER BRAKE UNIT INSPECTION

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Warning

•  Use of any brake fluid other than the specified brake fluid will cause permanent damage to brake components and will render the brakes inoperative. Failure to follow these instructions may result in personal injury.

Note

•  Inspect the fluid level in the master cylinder before performing the inspection procedures. If the brake fluid level is not at the MAX line, add specified brake fluid.

Power Brake Unit Operation Inspection

1.  Inspect all vacuum hoses and connectors. All unused vacuum piping must be capped. Vacuum hoses and their connections must be correctly secured and in good condition with no holes, cracks, or collapsed areas.

2.  Inspect the brake system for leakage or insufficient brake fluid. Repair if necessary.

3.  With the engine stopped, shift to P range and apply the parking brake.

4.  Press the brake pedal several times to exhaust all of the vacuum from the brake system.

Note

•  If the power brake unit is noisy when the brakes are applied, replace the component parts.

5.  Press and hold the brake pedal.

6.  Start the engine. If the power brake unit is operating normally, the brake pedal will move downward under constant foot pressure. If no movement occurs, the power brake unit is not functioning.

7.  Remove the vacuum hose from the power brake unit.

8.  Shift to P range and apply the parking brake. Start the engine. Manifold vacuum should be available from the vacuum hose. If manifold vacuum is not available, inspect all of the vacuum hoses and hose connections. Repair if necessary.

9.  Reconnect the vacuum hose and run the engine at idle for 10 min.

10.  Stop the engine and wait for 10 min.

11.  Apply the brake pedal with approx. 89 N {9.1 kgf, 20 lbf} of force. The brake pedal feel should be the same as normal power assisted brake operation for at least one application. If the brake pedal feel is normal, the power brake unit is normal. If the brake pedal feels hard, continue the inspection.

12.  Remove the vacuum hose from the power brake unit. Apply 57.3 kPa {430 mmHg, 16.9 inHg} of vacuum to the vacuum hose. If the vacuum does not leak off after 10 min, replace the power brake unit with a new one. If the vacuum leaks off, install a new check valve and/or new vacuum hoses.