Expedition 4WD V8-281 4.6L SOHC (1998)
Vacuum Brake Booster: Testing and Inspection
Inspection
1. Check the hydraulic brake system for leaks or insufficient fluid.
2. With the transmission in NEUTRAL, stop the engine and apply the parking brake control. Apply the brake pedal several times to exhaust all
vacuum in the system.
3. Apply 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 system is not functioning.
