E 150 1/2 Ton Van V6-4.2L VIN 2 (1997)
Vacuum Brake Booster Check Valve: Testing and Inspection
1. Start and run the engine.
2. Disconnect the vacuum line at the power brake booster check valve on the power brake booster.
3. Apply the brakes. The power brake booster check valve should retain enough vacuum in the power brake booster for at least one more power
assisted brake operation. If no power assist is felt, replace the power brake booster check valve and retest the system.
