Vapor Pressure Sensor Circuit
NOTE:
Vapor pressure sensor is available is 2 different configurations. Type "A" sensor has one vacuum port on each side of sensor. See Fig 2. Type "B" sensor has 2 vacuum ports on the same side of sensor.
- Disconnect vapor pressure sensor connector. Sensor has 2 vacuum ports and is mounted on top of EVAP charcoal canister underneath rear of vehicle. See Figure or Figure . Turn ignition on. Measure voltage between terminals VC and E2 at vapor pressure sensor connector terminals. See Fig 1. If voltage is 4.5-5.5 volts, go to next step. If voltage is not 4.5-5.5 volts, check wiring harness between sensor and ECM. See appropriate wiring diagram in WIRING DIAGRAMS article. Repair as necessary. If wiring is okay, replace ECM.
- Turn ignition off. Reconnect vapor pressure sensor connector. Access ECM harness connectors behind glove box. Disconnect vapor pressure sensor vacuum hose. See Fig 2. Turn ignition on.
- On ES300, backprobing ECM harness connector, measure voltage between terminals No. 18 (Brown wire) at ECM E10 connector and No. 17 (Pink wire) at ECM E7 connector. See Figure. On RX300, backprobing ECM harness connector, measure voltage between terminals No. 18 (Brown wire) at ECM E6 connector and No. 17 (Blue/Orange wire) at ECM E8 connector. See Figure. On all models, voltage reading should be as follows:
- 3.0-3.6 volts with no vacuum applied.
- 1.3-2.1 volts with .59 in. Hg (2.0 kPa) of vacuum applied.
- 4.2-4.8 volts with .22 psi (1.5 kPa) of pressure applied.
If voltage is not as specified, replace vapor pressure sensor.