DTC P1436: BY-PASS VALVE MALFUNCTION Toyota Prius I рестайлинг

Circuit Description

By-pass valve is used with the Hydrocarbon Adsorber Catalyst (HCAC) system. Before engine is started, by-pass valve is open. When engine starts, Engine Control Module (ECM) delivers an output signal to HCAC VSV. HCAC VSV opens, allowing vacuum to be applied to actuator, which causes the by-pass valve to close. When by-pass valve closes, exhaust gases pass into the HC absorber where the gases are stored until the temperature of front TWC increases. This prevents hydrocarbons from being delivered from vehicle when TWC temperature is low. After TWC becomes warm, the HCAC VSV closes and vacuum to by-pass valve is shut off, causing by-pass valve open. When rear TWC becomes warm, exhaust emissions are cleaned by the TWC. The HCAC VSV may also be operated during a deceleration condition when HC absorber is warm in order to scavenge the hydrocarbons that remain in the HC absorber. DTC is set if by-pass valve does not operate properly. Possible causes are

1. Defective vacuum hose or line.
2. Defective actuator.
3. Defective by-pass valve.
4. Defective front exhaust pipe.

Scheme 327

Scheme 328

Scheme 329

1. Check vacuum hose and line between HCAC VSV and the actuator for restrictions or 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. (Scheme 328) Actuator is located at front of three-way catalytic converter on exhaust pipe. (Scheme 327) If vacuum hose and line are okay, go to next step. If vacuum hose or line are restricted or damaged, repair or replace components as necessary.
2. Start engine and warm engine to normal operating temperature. Shut engine off. If using Toyota hand-held tester, go to next step. If Toyota hand-held tester is not available, go to step 4.
3. Connect hand-held tester to data link connector No. 3. see scheme 2 Start engine. Turn hand-held tester on. Select proper mode on hand-held tester to operate HCAC VSV. Go to step 5.
4. Disconnect electrical connector at HCAC VSV. Apply battery voltage and ground to electrical terminals on HCAC VSV to operate HCAC VSV. (Scheme 329) Start engine. Go to next step.
5. With engine idling and HCAC VSV operating, check that rod on actuator is pulled inward and that by-pass valve moves. If rod on actuator is not pulled inward and by-pass valve does not move, shut engine off and remove jumper wire (if used). Go to next step. If rod on actuator is pulled inward and by-pass valve moves, HCAC system is operating properly. Shut engine off. Reinstall electrical connector at HCAC VSV if removed and disconnect hand-held tester (if used).
6. Check for dirt on shaft of by-pass valve which would prevent by-pass valve operation. If no dirt exists, go to next step. If dirt exists, clean as necessary and recheck operation of by-pass valve.
7. Check for bent rod on actuator and for bent actuator mounting bracket. If rod and mounting bracket are okay, go to next step. If rod or mounting bracket are bent, repair or replace components as necessary.
8. Remove front exhaust pipe. Remove actuator from front exhaust pipe. Using vacuum pump, apply 9.83 in. Hg of vacuum to actuator while checking to see if rod on actuator is pulled inward. If rod is pulled inward, actuator is operating properly. Go to next step. If rod is not pulled inward, replace actuator.
9. Check that by-pass valve will rotate in front exhaust pipe. If by-pass valve will not rotate, replace front exhaust pipe. If by-pass valve will rotate, it is assumed that front exhaust pipe is defective. Repair or replace front exhaust pipe as necessary. Reinstall actuator and front exhaust pipe.