TOYOTA PREVIA 91-97 REPAIR MANUAL

4-20 DRIVEABILITYANDEMl:5SIONS CONTROLS

Fig. 55 ... and the old gasket

To install:

»Durint| and after the removal, use great care to protect the ip of
the sensor if it is to be reused. Do not allow it to come in con act
with fluids or dirt. Do not attempt to clean it or wash it.

5. Apply a coat of anti-seize compound to the bolt threads but D\T
   allow any to get on the tip of the sensor.


6. Position a new gasket, install and secure the sensor to 14 ft. II
   Nm).


7. Reattach the electrical wiring and insure a clean, tight conm
   tion.

Knock Sensor

•»To access the knock sensor, the engine and transmission m
removed from the vehicle.

OPERATION

s. (20

The knock sensor is fitted into the cylinder block to detect engine (nock-
ing. This sensor contains a piezoelectric element which generates a \e
when it becomes deformed, which occurs when the cylinder block vi rates
due to knocking. If the engine knocking occurs, ignition timing is ret rded
to suppress it.

TESTING

» See Figure 56

1. Remove the engine and transmission assembly from the vehic


2. Remove the intake manifold.


3. Disconnect the wiring from the knock sensor.


4. Using tool 09816-30010 or an equivalent socket, remove the nock
   sensor from the vehicle.


5. Using an ohmmeter, check that there is no continuity between fie ter-
   minal and the body.


6. If there is continuity, replace the sensor.


7. Install the knock sensor with the special tool, tighten securely ^> 33
   ft. Ibs. (44 Nm).


8. Connect the sensor wiring.


9. Install the intake manifold. Reinstall the engine in the vehicle.

st be

Ohmmeter

Fig. 56 Make sure there is no continuity between the body and

terminal of the knock sensor

REMOVAL & INSTALLATION

1. Remove the engine from the vehicle.


2. Remove the intake manifold.


3. Remove the knock sensor from the engine.


4. Inspect the vacuum hose over its entire length for any signs of crack-
   ing or splitting. The slightest leak can cause improper operation.
   To install:


5. Install the knock sensor; tighten securely to 34 ft. Ibs. (45 Nm).


6. Reinstall the intake manifold. Install the engine.

Idle Air Control (IAC) Valve

OPERATION

I See Figure 57

The rotary solenoid type IAC valve is located on the throttle body and

intake air bypassing the throttle valve is directed to the IAC valve through a

IAC valve

90914G49

Fig. 57 The Idle Air Control (IAC) valve is secured to the side of

the throttle body