Vapor Pressure Sensor (Prius)
WARNING:
Read service precautions before proceeding with service procedure. See SERVICE PRECAUTIONS .
- Ensure ignition is off. To test vapor pressure sensor supply voltage, disconnect electrical connector at vapor pressure sensor. Vapor pressure sensor is located on top of fuel tank and contains 3-pin electrical connector with Brown, Blue/Red and Yellow/Red wires. See Fig 1. It may be necessary to lower fuel tank for access to electrical connector at vapor pressure sensor.
- Disconnect electrical connector from vapor pressure sensor. Turn ignition on. Using voltmeter, measure vapor pressure sensor supply voltage between terminals No. 1 and 3 on wiring harness side of electrical connector for vapor pressure sensor. See Fig 1. DO NOT use center terminal. Vapor pressure sensor supply voltage should be 4.5-5.5 volts.
- If vapor pressure sensor supply voltage is within specification, turn ignition off. Reinstall electrical connector on vapor pressure sensor. Go to next step. If vapor pressure sensor supply voltage is not within specification, check wiring circuit between Engine Control Module (ECM) and vapor pressure sensor. See ENGINE PERFORMANCE in SYSTEM WIRING DIAGRAMS article in ELECTRICAL. ECM is located behind glove box. For illustration of ECM location, see ENGINE CONTROL MODULE under COMPONENT LOCATIONS.
- To test vapor pressure sensor output voltage, ensure electrical connector is installed on vapor pressure sensor. Turn ignition on. Remove fuel tank cap. Using voltmeter, measure vapor pressure sensor output voltage between terminals No. 2 and 3 on wiring harness side of electrical connector for vapor pressure sensor with electrical connector installed on vapor pressure sensor. See Fig 1.
- Vapor pressure sensor output voltage should be 3.0-3.6 volts. Replace vapor pressure sensor if vapor pressure sensor output voltage is not within specification. Turn ignition off. Reinstall fuel tank cap.