Barometric Pressure Sensor: Testing and Inspection

Barometric Pressure Sensor Circuit:

To test the Barometric Pressure Sensor, located on the air flow sensor, in the air cleaner housing, proceed as follows.

COMPONENT TEST
1. Connect a voltmeter between terminals 6 and 7 of the AFS Sensor connector.
Terminal 7: Barometric sensor output
Terminal 6: sensor ground
Terminal 4: sensor 5v power

Voltage (W/ key on and engine off)
^ At sea level
Approximately 4.0 volts.
^ At 2,000 ft.
Approximately 3.75 volts.
^ At 4,000 ft.
Approximately 3.50 volts.
^ At 6,000 ft.
Approximately 3.25 volts.

2. Warm the engine and bring it to a normal idle.

Barometric Pressure Sensor Test:

3. Slowly cover about half of the air cleaner air intake, observing the change in voltage. As pressure falls (vacuum increases), you should observe a drop in voltage.

HARNESS TEST:
1. Disconnect the air flow sensor connector and turn the key to the ON position.
2. Using a voltmeter, measure the power supply voltage between the harness connector terminal 4 and ground.

Voltage:
4.8 - 5.2 Volts.

3. Check for continuity between the air flow sensor harness connector terminal 6 and ground.

Continuity:
Should exist

4. Turn the ignition OFF and disconnect the engine control module connector and check for continuity between the air flow sensor harness connector terminal 7 and the engine control module harness connector terminal 16.

Continuity:
Should exist

5. Check for continuity between the air flow sensor harness connector terminal 7 and ground.

Continuity:
Should not exist

6. Check for continuity between the engine control module harness connector terminal 16 and ground.

Continuity:
Should not exist

7. Check for continuity between the air flow sensor harness connector terminal 6 and the engine control module harness connector terminal 17.

Continuity:
Should exist


If any of the previous tests produce unsatisfactory results, the harness will need to be repaired or replaced. Once repairs have been completed, clear the trouble codes and road test the vehicle to confirm that the repair has corrected the problem and the code doesn't return.

If the same trouble code reoccurs, it is possible that there is an intermittent failure of the component or the ECM. Check for looseness at all harness junctions and test for an intermittent failure.