Neon, 2000-2005

Camshaft Position Sensor

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Description & Operation



The camshaft position sensor (along with the crankshaft position sensor) provides inputs to the PCM to determine fuel injection synchronization and cylinder identification. From these inputs, the PCM determines crankshaft position. The camshaft position sensor is attached to the rear of the cylinder head.

A target magnet attaches to the rear of the camshaft and indexes to the proper position. The target magnet has four different poles arranges in an asymmetrical pattern. As the target magnet rotates, the camshaft position sensor senses the change in polarity. The sensor output switches from high (5.0 volts) to low (0.5 volts) as the target magnet rotates. When the north pole of the target magnet passes under the sensor, the output switches high. The sensor output switches low when the south pole of the target magnet passes underneath. The sensor also acts as a thrust plate to control camshaft endplay.

Click image to see an enlarged view

Fig.



Click image to see an enlarged view

Fig.



Click image to see an enlarged view

Fig.

Removal & Installation



  1. The camshaft position sensor is mounted to the rear of the cylinder head.
  2.  
  3. Remove brake booster hose and electrical connector from holders on end of cylinder head cover and reposition.
  4.  
  5. Disconnect electrical connectors from camshaft position sensor.
  6.  
  7. Remove camshaft position sensor mounting screws. Remove sensor.

    Click image to see an enlarged view

    Fig.

  8.  

To install:

  1. The camshaft position sensor is mounted to the rear of the cylinder head. The target magnet has two locating dowels that fit into machined locating holes in end of the camshaft.
  2.  
  3. Install target magnet in end of camshaft. Tighten mounting screw to 3.4 Nm (30 inch lbs.) torque.
  4.  
  5. Install camshaft position sensor. Tighten sensor mounting screws to 9 Nm (80 inch lbs.) torque.
  6.  
  7. Place brake booster hose and electrical harness in holders on end of valve cover.
  8.  
  9. Attach electrical connectors to camshaft position sensor.
  10.  

Testing



With A Test Light
  1. Check battery voltage. Voltage should be approximately 12.66 volts or higher to perform failure to start test.
  2.  
  3. Disconnect the harness connector from the coil pack.
  4.  
  5. Connect a test light to the B+ (battery voltage) terminal of the coil electrical connector and ground. The B+ wire for the DIS coil is the center terminal. Do not spread the terminal with the test light probe.
  6.  
  7. Turn the ignition key to the ON position. The test light should flash ON and then OFF. Do not turn the Key to OFF position, leave it in the ON position.
  8.  
  9. If the test light flashes momentarily, the PCM grounded the ASD relay. Proceed to step 5.
  10.  
  11. If the test light did not flash, the ASD relay did not energize. The cause is either the relay or one of the relay circuits. Use the DRB or scan tool to test the ASD relay and circuits. Check for codes and follow procedures.
  12.  
  13. Crank the engine. (If the key was placed in the OFF position after step 4, place the key in the ON position before cranking. Wait for the test light to flash once, then crank the engine.)
  14.  
  15. If the test light momentarily flashes during cranking, the PCM is not receiving a crankshaft position sensor signal.
  16.  

If the test light did not flash during cranking, unplug the crankshaft position sensor connector. Turn the ignition key to the off position. Turn the key to the ON position, wait for the test light to momentarily flash once, then crank the engine. If the test light momentarily flashes, the crankshaft position sensor is shorted and must be replaced. If the light did not flash, the cause of the no-start is in either the crankshaft position sensor/camshaft position sensor 8 volt supply circuit, or the camshaft position sensor output or ground circuits.

With An Oscilloscope

To test this sensor, you will need the use of an oscilloscope.

Visually check the connector, making sure it is attached properly and all of the terminals are straight, tight and free of corrosion. The output voltage of a proper operating camshaft or crankshaft position sensor switches from high (5.0 volts) to low (0.3 volts). By connecting an oscilloscope to the sensor output circuit, you can view the square wave pattern produced by the voltage swing.

 
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