Functional Test
- Check master cylinder fluid level. Inspect hydraulic system for leaks. Set shifter lever to Neutral or Park position, turn ignition off, and apply parking brake. Pump brake pedal several times to eliminate vacuum from system, then press and hold pedal in down position.
- Start and idle engine. If vacuum system is functioning properly, pedal will move downward under constant foot pressure. If no pedal motion occurs, vacuum booster is not functioning properly. Go to next step.
- Remove vacuum booster hose from power brake booster. Manifold vacuum should be available at power brake booster end of hose with engine at idle speed and transaxle in Park or Neutral position. Ensure all unused vacuum outlets are properly secured and vacuum hoses are in good condition. When established that manifold vacuum is available, connect vacuum booster hose to power brake booster and repeat step 2. If no downward movement of brake pedal is felt, replace power brake booster.
- Operate engine for at least 10 seconds at fast idle. Stop engine and let vehicle stand for 10 minutes, then depress brake pedal with approximately 20 lbs. (89 N) of force. Brake pedal should be same as noted with engine operating. If brake pedal feels hard replace power brake booster. If brake pedal movement feels spongy, bleed hydraulic system to remove air from system.
- Run engine at fast idle for 10 seconds or longer. Depress brake pedal and listen for noise. Compare results with a known good system. If brake pedal is noisy, replace it.