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Modulator Valve

  1. Disconnect all vacuum and exhaust pipe hoses from modulator valve. Cap fittings going to each EGR control solenoid. Blow into bottom fitting from exhaust pipe end.
  2. Apply 7 in. Hg to fitting No. 3 (from ported vacuum source). Vacuum should hold until pressure at bottom fitting is released. If further testing is required, see SYSTEM & COMPONENT TESTING article in ENGINE PERFORMANCE section.
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