Chrysler Front Wheel Drive Cars 6-CYL 1988-1995 Repair Information

Camshaft Position Sensor (CPS)

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OPERATION



Late Premier and Monaco

See Figure 1

If you are not sure whether your Premier or Monaco is designated as an early or late model, please refer to the model differentiation portion of this section.

Fuel injection synchronization and cylinder identification is provided through the Camshaft Position Sensor (CPS). The CPS utilizes a 180° target on the end of the camshaft. The rising edge of the 180° target indicates that the No. 1 cylinder is approaching Top Dead Center (TDC). The falling edge of the target indicates that the No. 5 cylinder is approaching TDC.



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Fig. Fig. 1: Camshaft position sensor-late Premier and Monaco vehicles

3.3L and 3.8L Engines

See Figures 2, 3 and 4

The CPS provides cylinder identification to the PCM. The sensor generates pulses as groups of notches on the camshaft sprocket pass underneath it. The PCM keeps track of the crankshaft rotation and identifies each cylinder by the pulses generated by the notches on the camshaft sprocket. Four crankshaft pulses follow each group of camshaft pulses.



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Fig. Fig. 2: Camshaft position sensor-3.3L and 3.8L engines



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Fig. Fig. 3: Camshaft sprocket and timing notches



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Fig. Fig. 4: Camshaft position sensor location in the chain case cover (pulley end of engine)

When the PCM receives two camshaft pulses followed by the long flat spot on the camshaft sprocket, it knows that the crankshaft timing marks for cylinder one are next (on the drive plate). When the PCM receives one camshaft pulse after the long flat spot on the sprocket, cylinder No. 2 crankshaft timing marks are next. After three camshaft pulses, the PCM knows cylinder four crankshaft timing marks follow. One camshaft pulse after the three pulses indicates cylinder five. The two camshaft pulses after cylinder No. 5 signals cylinder No. 6. The PCM can synchronize on cylinders No. 1 or No. 4.

When metal aligns with the sensor, voltage goes low (less than 0.5 volts). When a notch aligns with the sensor, voltage spikes high (5.0 volts). As a groups of notches pass under the sensor, the voltage switches from low to high then back to low again. The number of notches determine the amount of pulses. If available, an oscilloscope can display the square wave patterns of each timing event.

Top Dead Center (TDC) does not occur when notches on the camshaft sprocket pass below the sensor. TDC occurs after the camshaft pulse (or pulses) and after the 4 crankshaft pulses associated with the particular cylinder. The arrows and cylinder call in the illustration represent which cylinder the flat spot and notches identify, they do not indicate the TDC position.

The camshaft position sensor is mounted to the top of the timing case cover. The bottom of the sensor is positioned above the camshaft sprocket.

The distance between the bottom of sensor and the camshaft sprocket is critical to the operation of the system.

TESTING

For this procedure a dwell meter, or the equivalent, will be needed.

  1. Unplug the Camshaft Position Sensor (CPS) connector.
  2.  
  3. Turn the ignition ON .
  4.  
  5. Using a voltmeter, measure the voltage from the wiring harness connector 5-volt supply circuit (orange wire) to ground.
    1. If the voltage is 8-9.5 volts, skip to the next step.
    2.  
    3. If the voltage measured is lower than 8 volts, or greater than 9.5 volts, the CPS is not receiving the correct current to function properly. There is a problem in the wiring or related components.
    4.  

  6.  
  7. Turn the ignition OFF .
  8.  
  9. Attach the CPS wiring and engine wiring harness connectors back together.
  10.  
  11. Attach a dwell meter to the battery. Attach the lead probe of the dwell meter to the sensor signal wire (tan wire with yellow tracer) by backprobing the connector or by using jumper cables between the terminals.
  12.  
  13. Place the dwell meter out of the way of any moving components of the engine, and in a position in which it can be seen once the engine is started.
  14.  
  15. Turn the engine ON .
  16.  
  17. Watch the dwell meter for one or two minutes while the engine is idling. The dwell time shown should be a steady 49-51%. If there is any fluctuation, or the dwell time is not 49-51% the CPS is defective and must be replaced with a new one.
  18.  

REMOVAL & INSTALLATION



Late Premier and Monaco

See Figure 1

If you are not sure whether your Premier or Monaco is designated as an early or late model, please refer to the model differentiation portion of this section.

The Camshaft position sensor is located to the rear of the left cylinder head.

  1. Disconnect the negative battery cable.
  2.  
  3. Unplug the camshaft position sensor connector from the engine wiring harness.
  4.  
  5. Loosen and remove the sensor retaining bolts.
  6.  
  7. Pull the sensor out of the cylinder head.
  8.  

To install:
  1. If the old sensor is to be reused, clean the sensor of all dirt, oil and other containments.
  2.  
  3. Slide the sensor into its hole in the cylinder head.
  4.  
  5. Install and tighten the retaining bolt to 9 ft. lbs. (12 Nm).
  6.  
  7. Plug the sensor connector back into the engine wiring harness.
  8.  
  9. Connect the negative battery cable.
  10.  

3.3L and 3.8L Engines

See Figures 2, 3 and 4

  1. Disconnect the negative battery cable.
  2.  
  3. Unplug the camshaft position sensor electrical connector from the wiring harness.
  4.  
  5. Loosen the camshaft position sensor retaining bolt enough to allow the slot in the sensor to slide past the bolt.
  6.  
  7. Pull the sensor up and out of the chain case cover. Do not pull on the sensor wires. There is an O-ring on the sensor case and may make the removal slightly difficult. A light tap on the top of the senor prior to removal may reduce the force needed for removal.
  8.  

To install:
  1. If installing the original sensor, clean off the old spacer on the sensor face. A new spacer must be attached to the face before installation. Inspect the O-ring for damage (cuts, tears, etc.), replace with a new O-ring if any damage is found. If the sensor is being replaced with a new one, confirm that the paper spacer is attached to the face and O-ring is positioned in the groove of the new sensor.
  2.  
  3. Apply a couple drops of clean engine oil to the O-ring prior to installation. Install the sensor into the chain case cover and push the sensor down until contact is made with the camshaft gear. While holding the sensor in this position, install and tighten the retaining bolt to 9 ft. lbs. (12 Nm).
  4.  
  5. Plug the sensor's connector back into the engine wiring harness. Position the connector away from the accessory drive belt.
  6.  
  7. Connect the negative battery cable.
  8.  

 
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