Diagnosis & Repair
WARNING: This page is about a different car, the 2002 Toyota Prius. However, it is still accessible from the selected car via links, so may be relevant.
- Check vacuum hoses and lines between intake manifold and HCAC VSV, and between HCAC VSV, vacuum sensor and the actuator for correct installation, loose connections, restrictions, disconnected hoses and damage. 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. See Figure. Vacuum sensor is located at passenger's side front corner of the engine and contains Black 3-pin connector with Brown, Violet/White and Yellow/Red wires. See Figure. Actuator is located at front of TWC on exhaust pipe. See Figure. If vacuum hoses and lines are okay, go to next step. If vacuum hose or line are restricted, disconnected or damaged, repair or replace components as necessary.
- Check for open and short in wiring harness and electrical connectors between HCAC VSV and ECM. See WIRING DIAGRAMS article. ECM is located behind glove box. See Figure. If wiring harness and electrical connectors are okay, go to next step. If wiring harness or electrical connector is defective, repair as necessary.
- Disconnect electrical connector and vacuum hoses at HCAC VSV. Using ohmmeter, check that continuity exists between electrical terminals on HCAC VSV and resistance is 33-39 ohms at 68°F (20°C). Replace HCAC VSV if no continuity exists or resistance is not within specification.
- 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.
- To test HCAC VSV operation, apply air pressure to port "E" on HCAC VSV. Ensure air flows from air filter and not from port "F". See Fig 1. 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. See Fig 1. If HCAC VSV operates properly, go to next step. If HCAC VSV does not operate properly, replace HCAC VSV.
- If Toyota hand-held tester is available, go to next step. If Toyota hand-held tester is not available, go to step 8.
- Disconnect vacuum hose at vacuum sensor. Connect hand-held vacuum pump to disconnected vacuum hose for vacuum sensor. Connect hand-held tester to Data Link Connector (DLC) No. 3 at driver's side of instrument panel. See Figure. Turn hand-held tester on. Select proper mode on hand-held tester to operate HCAC VSV. Go to step 9.
- Disconnect vacuum hose at vacuum sensor. Remove glove box for access to ECM with electrical connectors still installed on ECM. See Figure. Connect jumper wire between body ground and terminal No. 20 (Black/White wire) at ECM electrical connector E9 to operate HCAC VSV. See Figure. This is the HCC terminal on ECM. Turn ignition on. Go to next step.
- Using hand-held vacuum pump, apply 16.24 in. Hg of vacuum to disconnected vacuum hose for vacuum sensor. Note vacuum reading after 30 seconds. If vacuum reading is not 7.38 in. Hg or more, turn ignition off. Remove jumper wire or hand-held tester (if used) and go to next step. If vacuum reading is 7.38 in. Hg or more, turn ignition off. Remove jumper wire or hand-held tester (if used). Check for defective vacuum hose between check valve and intake manifold. Check valve is located in the vacuum hose between intake manifold and HCAC VSV. Repair or replace vacuum hose as necessary.
- Check operation of check valve. Check valve is located in the vacuum hose between intake manifold and HCAC VSV. If check valve is okay, go to next step. If check valve is defective, replace check valve.
- Using hand-held vacuum pump, check that HCAC VSV and actuator will hold vacuum. If HCAC VSV and actuator will hold vacuum, check for defective vacuum hoses between check valve, HCAC VSV, vacuum sensor and actuator. If HCAC VSV or actuator will not hold vacuum, replace components as necessary.