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HCAC Vacuum Switching Valve

WARNING: Read service precautions before proceeding with service procedure. See SERVICE PRECAUTIONS .
  1. Remove HCAC Vacuum Switching Valve (VSV). See Figure. HCAC VSV is located on bracket bolted to timing chain end of engine and uses a Brown 2-pin electrical connector with Black and Black/White wires.
  2. Using ohmmeter, check that continuity exists between electrical terminals on HCAC VSV and that resistance is 33-39 ohms at 68°F (20°C). Replace HCAC VSV if no continuity exists or resistance is not within specification.
  3. Ensure no continuity exists between each electrical terminal and body of HCAC VSV body. Replace HCAC VSV if continuity exists between electrical terminal and body of HCAC VSV.
  4. To test HCAC VSV operation, apply air pressure to port "E". Ensure air flows from air filter and not from port "F". Perform STEP 1 in illustration. See Fig 1.
  5. Apply battery voltage and ground to electrical terminals on HCAC VSV. Apply air pressure to port "E". Ensure air flows from port "F" and not from air filter. Perform STEP 2 in illustration. See Fig 1. Replace HCAC VSV if defective.
    Fig 1: Testing Hydrocarbon Adsorber Catalyst Vacuum Switching Valve (Prius)
    G00023173Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002