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Diagnosis & Repair (Using OBD-II Scan Tool)

WARNING: This page is about a different car, the 2003 Lexus RX 300. However, it is still accessible from the selected car via links, so may be relevant.
  1. Check that fuel tank cap is Toyota genuine parts. Replace to TOYOTA genuine parts as necessary. If okay, go to next step.
  2. Check that fuel tank cap is correctly installed. If okay, go to next step.
  3. Check fuel tank cap. Replace fuel tank cap as necessary. If okay, go to next step.
  4. Check filler neck for damage. Remove the fuel tank cap. Visually inspect the filler neck for damage. Replace filler pipe as necessary. If okay, go to next step.
  5. Check for cracks, deformation and loose connection of fuel tank, charcoal canister, fuel tank filler pipe, hoses and tubes around fuel tank and charcoal canister. See Figure. Repair or replace as necessary. If okay, go to next step.
  6. Check vacuum hoses between vapor pressure sensor and fuel tank, charcoal canister and VSV for pressure switching valve, and VSV for pressure switching valve and charcoal canister. Check that the vacuum hose is connected correctly. Check the vacuum hose for looseness and disconnection. Check the vacuum hose for cracks, holes and damages. Repair or connect VSV or sensor connector as necessary. If components are okay, go to next step.
  7. Check for proper connection of the fuel tank and fuel evaporation pipe, fuel evaporation pipe and fuel tube under the floor, fuel tube under the floor and charcoal canister. Check the hose and tube for cracks, hole and damage. Repair or replace as necessary. If okay, go to next step.
  8. Check VSV connector for EVAP, VSV connector for CCV, VSV connector for pressure switching valve and vapor pressure sensor connector for looseness and disconnection. Repair or connect VSV or sensor connector as necessary. If okay, go to next step.
  9. Check vacuum hoses. Check that the vacuum hose is connected correctly. Check the vacuum hose for looseness and disconnection. Check the vacuum hose for cracks, holes damage, and blockages. Repair or replace as necessary. If okay, go to next step.
  10. Remove the glove compartment. Turn the ignition switch ON. Measure the voltage between terminals VC and E2 of the ECM connector. See Figure. If voltage is 4.5-5.5 volts, go to next step. If voltage is not to specification, check and replace ECM.
  11. Remove glove compartment. Turn the ignition switch ON. Measure voltage between terminals PTNK and E2 of the ECM connectors. Disconnect the vacuum hose from the vapor pressure sensor. Using the MITYVAC (Hand-Held Vacuum Pump), apply a vacuum of 1.18 in. Hg (4.0 kPa, 30 mm Hg) to the vapor pressure sensor. The vacuum applied to the vapor pressure sensor must be less than 19.7 in. Hg (66.7 kPa, 500 mm Hg). See Figure. If voltage is 2.9-3.7 volts, or 0.5 volts or less, go to step  13. If voltage is not to specification, go to next step.
  12. Check for open and short in harness and connector between vapor pressure sensor and ECM. Repair or replace harness or connector as necessary. If okay, go to next step.
  13. Remove the glove compartment. Turn the ignition switch ON. Check the VSV function by connecting a jumper wire between terminal EVP1 of the ECM connector and body ground. Disconnect jumper wire between terminal EVP1 of the ECM connector and body ground. When VSV is ON, airflow from port "E" should flow out through port "F". When VSV is OFF, air does not flow from port "E" to port "F". See Fig 1. If okay, go to step  16. If not okay, go to next step.
    Fig 1: Checking VSV For EVAP
    G00165074Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
  14. Check operation of VSV for EVAP. See SYSTEM & COMPONENT TESTING - ES300 & RX300 article. If okay, go to next step. If not okay, replace VSV and clean vacuum hoses between throttle body and VSV for EVAP, and VSV for EVAP and charcoal canister, and then check charcoal canister.
  15. Check for open and short in harness and connector between EFI relay and VSV for EVAP, and VSV for EVAP and ECM. Repair or replace harness or connector as necessary. If okay, check and replace ECM.
  16. Remove the glove compartment. Turn the ignition switch ON. Check the VSV function. Connect jumper wire between terminal CCV of the ECM connector and body ground, then disconnect jumper wire. When VSV is ON, air does not flow from port "E" to port "F". When VSV is OFF, air from port "E" flows out through port "F". See Fig 2. If okay, go to step  19. If not okay, go to next step.
    Fig 2: Connecting Jumper Wire Between ECM CCV Terminal & Ground
    G00165075Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
  17. Check operation of VSV for CCV. See SYSTEM & COMPONENT TESTING - ES300 & RX300 article. If not okay, replace VSV and charcoal canister, and then clean vacuum hose between charcoal canister and VSV for CCV as necessary. If okay, go to next step.
  18. Check for open and short in harness and connector between EFI relay and VSV for CCV, and VSV for CCV and ECM. Repair or replace harness or connector as necessary. If okay, check and replace ECM.
  19. Remove the glove compartment. Turn the ignition switch ON. Check the VSV function by connecting a jumper wire between terminal TBP of the ECM connector and body ground, then disconnect jumper wire. When VSV is ON, air from port "E" flows out through port "F". When VSV is OFF, air does not from flow port "E" to port "F". See Fig 3. If okay, go to step  22. If not okay, go to next step.
    Fig 3: Checking VSV For Pressure Switching Valve
    G00165076Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
  20. Check operation of VSV for pressure switching valve. See FUEL EVAPORATION SYSTEM under FUEL EVAPORATION SYSTEMS in SYSTEM & COMPONENT TESTING - ES300 & RX300 article. If okay, go to next step. If not okay, replace VSV and charcoal canister, and then clean vacuum hoses between charcoal canister and VSV for pressure switching valve, and VSV for pressure switching valve and fuel tank.
  21. Check for open and short in harness and connector between EFI relay and VSV for pressure switching valve, and VSV for pressure switching valve and ECM. Repair or replace harness or connector as necessary. If okay, check and replace ECM.
  22. Check the fuel tank over fill check valve. FUEL SYSTEM in SYSTEM & COMPONENT TESTING - ES300 & RX300 article. Replace fuel tank overfill check valve or fuel tank. If okay, check and replace charcoal canister.
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