Quest 1995-1996

Barometric/Manifold Absolute Pressure Sensors

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Operation



Specific to:

Mercury Villager 1993-2000

Nissan Quest 1993-2000

On 1998 California emissions and 1999-00 vehicles, the MAP/BARO sensor detects either intake manifold absolute pressure (MAP) or ambient barometric pressure (BARO) from the MAP/BARO solenoid. The sensor sends a signal to the PCM, which is used to control the evaporative emissions system. MAP/BARO sensors are not used on 1993-97 vehicles.

Click image to see an enlarged view

Fig. Manifold absolute pressure/barometric pressure (MAP/BARO) sensor connector location

Specific to:

Mercury Villager 1993-2000

Nissan Quest 1993-2000

On 1998 California emissions and 1999-00 vehicles, the MAP/BARO solenoid provides the MAP/BARO sensor with either intake manifold vacuum or ambient barometric pressure. When voltage is sent to the solenoid by the PCM, the solenoid allows the MAP/BARO sensor to monitor barometric pressure. When the voltage is turned off, intake manifold vacuum is monitored. MAP/BARO solenoids are not used on 1993-97 vehicles.

Removal & Installation



Specific to:

Mercury Villager 1993-2000

Nissan Quest 1993-2000

  1. Disconnect the negative battery cable.
  2.  
  3. Remove the retaining clip and position the EVAP system test port aside.
  4.  
  5. Disconnect the MAP/BARO sensor electrical connector.
  6.  
  7. Disconnect the vacuum hose.
  8.  
  9. Remove the two MAP/BARO sensor bolts and remove the sensor.
  10.  
  11. The installation is the reverse of removal.
  12.  

Specific to:

Mercury Villager 1993-2000

Nissan Quest 1993-2000

  1. Disconnect the negative battery cable.
  2.  
  3. Disconnect the MAP/BARO solenoid electrical connector.
  4.  
  5. Remove the three vacuum hoses from the solenoid.
  6.  
  7. Remove the solenoid retaining nut and remove the solenoid from the vehicle.
  8.  
  9. The installation is the reverse of removal.
  10.  

Testing



Specific to:

Mercury Villager 1993-2000

Nissan Quest 1993-2000

  1. Remove the MAP/BARO sensor, but leave the electrical connector connected.
  2.  
  3. Disconnect the vacuum hose from the sensor.
  4.  
  5. Using a voltmeter set to the DC range, connect the negative lead of a voltmeter lead to the negative battery terminal.
  6.  
  7. With the MAP/BARO sensor electrical connector still connected, insert the positive lead probe into the back of the pink wire (pin 2) terminal of the connector.
  8.  
  9. With the ignition switch on and the engine OFF , observe and record the voltmeter reading.
    WARNING
    Do not apply more than 27.56 in. Hg (93.3 kPa) of vacuum, or more than 29.92 in. Hg (101.3 kPa) of pressure to the MAP/BARO sensor or damage may occur.

  10.  
  11. Connect a hand vacuum pump to the sensor.
  12.  
  13. Apply 7.87 in. Hg (26.7 kPa) of vacuum to the sensor and observe the voltmeter reading.
  14.  
  15. The reading should be 1.0-1.4 volts lower than the recorded reading from step 5. If not, the sensor may be faulty.
  16.  

Specific to:

Mercury Villager 1993-2000

Nissan Quest 1993-2000


NOTE
Two jumper wires are required for the following tests. An in-line fuse holder with a 30 amp fuse should be spliced in the jumper wire that will be connected to the positive battery terminal to prevent possible damage to the battery, wiring, and components of the circuit being tested.

  1. Remove the three vacuum hoses from the MAP/BARO solenoid.
  2.  
  3. Disconnect the MAP/BARO solenoid electrical connector.
  4.  
  5. Connect the fused jumper wire between the positive battery terminal and terminal pin 1 of the solenoid.
  6.  
  7. Connect the other jumper wire between the negative battery terminal and terminal pin 2 of the solenoid.
  8.  
  9. Blow air into port A . There should be free airflow out of port B .
  10.  
  11. Plug port B and blow air into port A . There should be no airflow out of port C .
  12.  
  13. Disconnect the jumper wires.
  14.  
  15. Plug port C and blow air into port A . There should be no airflow out of port B .
  16.  
  17. Blow air into port A . There should be free airflow out of port C .
  18.  
  19. If the solenoid fails any of the preceding tests, replace the solenoid.

    Click image to see an enlarged view

    Fig. Jumper wire connections for MAP/BARO solenoid testing-1998 California emissions and 1999-00 vehicles

  20.  

 
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