Manifold Absolute Pressure Sensor: Inspection

Check that the manifold absolute pressure sensor has no deformation, cracks or other damages.
Connect dry-cell battery positive terminal to terminal No. 3 and dry-cell battery ground terminal to terminal No. 1, circuit tester positive terminal to terminal No. 2 and the circuit tester ground terminal to terminal No. 1.
NOTE:
- Use new dry-cell batteries.
- Using circuit tester, check that the initial voltage of a single dry-cell battery is 1.6 V or more. And also check that the voltage of three batteries in series is between 4.8 V and 5.2 V.
- For power supply, 5 V DC voltage source can also be used.
Fig 1: Checking Voltage At Normal Atmospheric Pressure
Courtesy of SUBARU OF AMERICA, INC.

Check the voltage at a normal atmospheric pressure.

NOTE: The atmospheric pressure at higher altitude is lower than normal. Therefore, the voltage is lower than the standard value.

Terminal No.	Standard
2 (+) and 1 (-)	Approx. 4.2 V (when 25°C (77°F))

Connect the Mighty Vac to the pressure port (A) of manifold absolute pressure sensor.

Fig 2: Identifying Manifold Absolute Pressure Sensor Pressure Port
Courtesy of SUBARU OF AMERICA, INC.

Check the voltage when generating vacuum using Mighty Vac.

CAUTION: Do not apply vacuum of less than -88 kPa (-0.9 kg/cm² , -12.8 psi). Doing so may damage the manifold absolute pressure sensor.

NOTE: When vacuum occurs at the pressure port of manifold absolute pressure sensor, the voltage will drop from the value as in step 3).

Pressure	Terminal No.	Standard
-88 kPa (-0.9 kg/cm² , -12.8 psi)	2 (+) and 1 (-)	Approx. 1 V (when 25°C (77°F))