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Functional Test

  1. Turn ignition off. Disconnect 8-pin connector on vacuum switch control box. See Fig 1 . Measure resistance between terminals No. 5 and No. 6 on control box connector. If continuity exists, go to step 3). If continuity does not exist, remove hose No. 7 from vacuum hose manifold. See Fig 2 . Connect a "T" fitting from a vacuum gauge between vacuum hose manifold and vacuum switch.
  2. Start engine and idle. Check vacuum gauge. If vacuum is greater than 1.2 in. Hg, check routing of hose No. 7. If vacuum is less than 1.2 in. Hg, replace vacuum switch and/or repair open or short in Black/Yellow or White wire in control box.
  3. Turn ignition switch to ON position. Measure voltage between Black/Yellow terminal and body ground on wire harness. If battery voltage does not exist, repair open or short in Black/Yellow wire between 8-pin connector and No. 12 fuse. If battery voltage is present, vacuum switch is okay.
    Fig 1: Identifying Vacuum Switch Control Box Connector
    G90G17125Courtesy of AMERICAN HONDA MOTOR CO., INC.
    Fig 2: Locating Vacuum Hose No. 7
    G90H17126Courtesy of AMERICAN HONDA MOTOR CO., INC.