Vapor Pressure Sensor Vacuum Switching Valve

1. Remove vapor pressure sensor Vacuum Switching Valve (VSV). Vapor pressure sensor VSV is located on charcoal canister and has 3 vacuum ports. See Figure.
2. Using ohmmeter, measure resistance between vapor pressure sensor VSV terminals. If resistance is not 37-44 ohms at 68° F(20°C), replace vapor pressure sensor VSV. If resistance is 37-44 ohms, check for continuity between each VSV electrical terminal and body of vapor pressure sensor VSV. If continuity exists, replace vapor pressure sensor VSV.
3. To test vapor pressure sensor VSV operation, apply air pressure to port "E". Ensure air flows from port "E" to port "F". See Fig 1.
4. Apply battery voltage and ground to electrical terminals on vapor pressure sensor VSV. Ensure air flows from port "E" to port "F". See Fig 1. Replace vapor pressure sensor VSV if defective.

Fig 1: Inspecting Vapor Pressure Sensor Operation

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