Brake Booster Inspection

1. Remove the vacuum hose from the power brake booster. Manifold vacuum should be available at the brake booster end of the hose with the engine at idle speed and the transaxle in PARK or NEUTRAL. Make sure all unused vacuum outlets are properly capped, hose connectors are properly secured and vacuum hoses are in good condition.

When it is established that manifold vacuum is available to the power brake booster, connect the vacuum 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.
2. Operate the engine a minimum of 10 seconds at fast idle. Stop the engine, and let the vehicle stand for 10 minutes. Then, apply the brake pedal with approximately 89 N (20 lb) of force. The 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 check valve, then repeat the test. If brake pedal still feels hard, replace the power brake booster.

If the brake pedal movement feels spongy, bleed the hydraulic system to remove air from the system.