TOYOTA PREVIA 91-97 REPAIR MANUAL

DRIVEABILITY AND EMISSIONS CONTROLS 4-9

Ohmmeter

n

No Continuity

Fig. 16 Check for ground on the VSV using an ohmmeter

Fig. 17 Remove the hose clamp for the lower tube on the char-

coal canister

NON-FILTERED TYPE

1. Check that air does not flow from port E to port F.

2. Connect the vacuum switching valve terminals to the battery.


3. Check that air flows from port E to port F.


4. If the VSV fails this test replace it. Any doubts perform the following test.


5. Remove the VSV


6. Check for an open circuit. Using an ohmmeter, measure the resistance
   (ohms) between the two terminals of the valve. The resistance (cold) should be
   30-34 ohms. If the resistance is not within specifications, replace the VSV.


7. Check for a short circuit within the valve. Using an ohmmeter, check
   that there is no continuity between the terminals and the VSV body. If there
   is continuity, replace the VSV.

REMOVAL & INSTALLATION

replacing any EVAP system hoses, always use hoses that

are fuel-resistant or are marked EVAP. Use of hose which is not

fuel-resistant will lead to premature hose failure.

Charcoal Canister

» See Figures 17, 18, 19, 20 and 21

Label and disconnect the lines running to the canister. Make sure to plug

the lines with a bolt or like. Disconnect the wiring harness. Unbolt and remove

the charcoal canister from the vehicle. Do not attempt to wash the charcoal

canister. Also be sure that no activated carbon comes out of the canister during

the cleaning process. Attach the charcoal canister to its mounting bracket and

secure. Connect the vacuum hoses in their proper locations.

Vacuum Switching Valve (VSV)

» See Figure 22

Disconnect the wiring from the VSV. Label and removed the vacuum

hoses from the valve. Loosen the nut and extract the VSV from the No. 2 air

inlet duct.

Exhaust Gas Recirculation System

OPERATION

The EGR system reduces oxides of nitrogen. This is accomplished by
recirculating some of the exhaust gases through the EGR valve to the intake
manifold, lowering peak combustion temperatures.

Fig. 18 Disconnect the wiring harness leading to the canister

:

Fig. 19 Remove the two canister mounting bolts