E4 - Component Isolation Check

- Key OFF.

- Reconnect the vacuum gauge to the same point as in Step E1, but leave the rest of the system connected. E1 - Vacuum Check

- Key ON, engine running at idle until vacuum reaches 437-533 mm-Hg (18-21 in-Hg).

- Key OFF.

- Observe vacuum gauge for 1 minute.

- Does vacuum pressure drop more than 1 in-Hg?

YES -- Disconnect each component one at a time and Repeat the test procedures in Step E4 until the leaking component is found. Plug the disconnected vacuum line while performing the test procedures. Repair or replace as required. On vehicles with dash-mounted booster, Replace power brake booster check valve also.

NO -- GO to E5. E5 - Booster Leak Check