N4 - Component Isolation Check

- Key OFF.

- Reconnect the vacuum gauge to the same point as in Step N1, but leave the rest of the system connected.

- Key ON, engine running at idle until vacuum reaches 437-533 mm Hg (17-21 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 N4 until the leaking component is found. Plug the disconnected vacuum line while performing the test procedures. Repair or replace as required.

NO -- Go to N5.