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EGR Vacuum Modulator

NOTE: When testing EGR vacuum modulator, it may be necessary to monitor engine RPM by using scan tool. For scan tool connections, see IDLE SPEED & MIXTURE in ADJUSTMENTS article.
  1. Mark vacuum hose locations and disconnect vacuum hoses from EGR vacuum modulator. Block ports "P" and "R" on EGR vacuum modulator. See Figure.
    NOTE: Ports "P" and "R" are the double ports on side of EGR vacuum modulator. Port "Q" is single port on side of EGR vacuum modulator.
  2. Apply air pressure to port "Q". See Figure. Air should flow freely through air filter side of EGR vacuum modulator.
  3. Start and operate engine at specified RPM. See EGR VACUUM MODULATOR TESTING SPECIFICATIONS  table. Repeat test procedures in steps 1) and 2). Strong resistance of airflow should be felt. Replace EGR vacuum modulator if resistance is not felt. Reconnect vacuum hoses to proper locations.
EGR VACUUM MODULATOR TESTING SPECIFICATIONS

Application Engine RPM
LX 450/Land Cruiser 2500
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