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By-Pass Air Control (BAC) Valve

  1. Ensure air flows through port A when valve is cold. See Fig 1 . If not, replace BAC valve.
  2. Measure resistance of Idle Speed Control (ISC) valve at 2 wire connector of BAC valve. Resistance should be between 10.8-12.3 ohms, at normal operating temperature. If not, replace BAC valve.
Fig 1: BAC Valve Testing
G94834Courtesy of MAZDA MOTORS CORP.