Functional Test

Inspect all vacuum hoses and connections. All unused vacuum connectors should be capped. Hoses and their connections should be properly secured and in good condition with no holes or collapsed areas. Inspect the hose containing the check valve for damage. Check the power brake booster system operation as follows:

1. Check the hydraulic brake system for leaks or insufficient fluid.
2. With the transaxle in PARK (P) or NEUTRAL (N), stop the engine, and apply the parking brake. Depress the brake pedal several times to exhaust all vacuum in the system.
3. With the engine turned off and all vacuum in the system exhausted, depress the brake pedal and hold it in the applied position. Start the engine. If the vacuum system is operating, the brake pedal will tend to move downward under constant foot pressure. If no motion is felt, the power brake booster is not functioning.
4. Remove the vacuum booster hose from the power brake booster. Manifold vacuum should be available at the power brake booster end of the hose with the engine at idle speed and the transaxle in NEUTRAL (N). Be sure that all unused vacuum outlets are properly secured, and that vacuum hoses are in good condition. When it is established that manifold vacuum is available, connect the vacuum booster hose to the power brake booster and repeat step 3. If no downward movement of the brake pedal is felt replace the power brake booster.
5. Operate the engine a minimum of 10 seconds at fast idle. Stop the engine, and let the vehicle stand for 10 minutes, then depress the brake pedal with approximately 20 pounds of force. The brake pedal feel (brake application) should be the same as that noted with the engine operating. If the brake pedal feels hard (no power assist), replace the vacuum booster hose, then repeat the test. If brake pedal still feels hard, replace the power brake booster. If brake pedal movement feels spongy, bleed the hydraulic system to remove air from the system.
6. Run the engine at fast idle for 10 seconds or longer. Depress brake pedal and listen for noise. Compare results with a known good system. If power brake booster is noisy, replace it.