Focus ZTS L4-2.0L DOHC VIN 3 (2001)
Vacuum Brake Booster: Testing and Inspection
Brake Booster
1. Check all hoses and connections. All unused vacuum connectors should be capped. Hoses and their connections should be correctly secured and in
good condition with no holes and no collapsed areas. Inspect the check valve on the brake booster for damage.
2. Check the hydraulic brake system for leaks or low fluid.
3. With the transaxle in PARK (automatic transaxle) or in NEUTRAL (Manual transaxle), stop the engine and apply the parking brake. Pump the
brake pedal several times to exhaust all vacuum in the system.
4. With the engine turned OFF and all vacuum in the system exhausted, apply the brake pedal and hold it down. 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 vacuum booster system is
not functioning.
5. Remove the vacuum hose from the brake booster. Manifold vacuum should be available at the brake booster end of the hose with the engine at idle
sped and the transaxle in PART or NEUTRAL. Make sure that all unused vacuum outlets are correctly capped, hose connectors are correctly
secure and vacuum hoses are in good condition. When it is established that manifold vacuum is available to the brake booster, connect the vacuum
hose to the brake booster and repeat Step 3. If no downward movement of the brake pedal is felt, install a new brake booster.
6. 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 lbs.) of force. The pedal feel (brake applications) should be the same as noted with the engine running. If the brake pedal
feels hard (no power assist), install a new check valve and then repeat the testing. If the brake pedal stills feels hard, install a new brake booster. If
the brake pedal movement feels spongy, bleed the brake system.
