Manifold Pressure/Vacuum Sensor: Testing and Inspection

TESTING PROCEDURE:

NOTE: While trouble shooting, always check the wiring, fuses and connectors for good condition and routing. Use the wiring diagrams found in SCHEMATIC DIAGRAMS to supplement your testing efforts.

Color Code Legend:

Checking ECU Ground Connections:

1. Turn ignition OFF.
2. Access fuel injection ECU by removing the passenger side kick panel and glove compartment.
3. Check fuel injection ECU ground connections. They should make good contact and fit tight.

Removing ECU Connector:

4. Remove fuse #1 (located in central electric unit behind ash tray) to interrupt the power supply. Then remove the ECU connector by pressing up the latch and folding out the wire cluster.

Removing Protective Sleeve:

5. Remove connector protective sleeve and reinstall fuse #1 for testing.
CAUTION: ^ Never check connections from the front. Connectors can get damaged and worsen the problem.
^ Check connections through the holes in the connector.
^ Connection pin numbers are printed on the connector side.

Installing Connector:

6. Disconnect intake manifold pressure sensor hose.
7. Reconnect the ECU connector "loosely" to the fuel injection control unit.

Checking Voltage At Pin 7 And 11:

8. Turn ignition ON.
9. Connect a voltmeter between ground and pin 11.

Reading: approx. 5 volts

If not, check power source and ground for ECU. Repair as necessary. If no fault can be found, replace and retest with new fuel injection ECU.
10. Connect a voltmeter between ground and pin 7.

Reading: approx. 5 volts

If not, check wiring and connectors between pin 11 and intake manifold pressure sensor. Check wiring and connectors between pin 7 and intake manifold pressure sensor. Check wiring and connectors between pin 6 and intake manifold pressure sensor. Repair as needed. If no fault can be found, replace and retest with new intake manifold pressure sensor.

Checking Pin 7 And 11:

11. Connect voltmeter to pin 7 and 11.
12. Connect a vacuum pump to the pressure sensor.
13. Apply vacuum to the sensor. Voltage should decrease with increasing vacuum.

Reading at 100 kPa: approx. 4.4 volts
Reading at 80 kPa: approx. 3.2 volts
Reading at 60 kPa: approx. 2.1 volts
Reading at 40 kPa: approx. 1.1 volts
Reading at 20 kPa: approx. 0.5 volts

If voltage does not fall, or drop is excessive, replace and retest with new intake manifold pressure sensor.
14. Turn ignition OFF.

Removing Connector:

15. Remove connector from fuel injection ECU.
16. Remove the #1 fuse and reconnect the ECU connector. Ensure that the rubber seal in the connector is installed before it is connected to the ECU.
17. Reinstall the #1 fuse.
18. After testing, disconnect all test equipment, reconnect all connectors, hoses and remount all panels.