112
Fig.172
3-way connector (figure. 173)
a.
Supply 5V voltage
b.
Negative pole signal
c.
Positive pole signal
When engine is shut down, the sensitive membrane will bent according to the value of atmospheric
pressure (mmHg). After the ignition switch is switched on, the actual atmospheric pressure may be
obtained by this method. When engine is running, the vacuum will produce a mechanical effect on the
ceramic membrane of the sensor resulting in the change of resistance.
For ECU supplies a absolutely constant 5V voltage, the change of output voltage caused by the change
of resistance is indicated in figure. 174.
Sensor supplies the most important data to ECU for calculating the intake air volume. When the pressure
signal is P
＜
97mmHg or P
＞
783mm Hg
，
if the throttle valve position sensor doesn’t fail, the operation
comeback will be performed according to the throttle valve angle and speed value stored in the calibration
scale. If throttle valve fails, only one comeback value may be applied——about 442mmHg.
Note: If absolute pressure sensor needed to be replaced, the connecting pipe must have the same
diameter and length as the original pipe.
Fig.173
Fig.174
