Avenger, Sebring Coupe, Stratus Coupe, 1999-2006

Camshaft Position Sensor

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Description & Operation



Not for Dodge Stratus Sedan

The CMP sensor contains a Hall-effect device that provides cylinder identification to the Powertrain Control Module (PCM). The sensor generates pulses as groups of notches on the camshaft sprocket pass underneath it. The PCM keeps track of crankshaft rotation and identifies each cylinder by the pulses generated by the notches on the camshaft sprocket. Crankshaft pulses follow each group of camshaft pulses.

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.

On 4-cylinder engines, the camshaft position sensor mounts to the rear of the cylinder head. The sensor also serves as a thrust plate to control endplay of the camshaft.

The 6-cylinder engines are equipped with a camshaft driven mechanical distributor, which is equipped with an internal camshaft position (fuel sync) sensor.

Click image to see an enlarged view

Fig.



Click image to see an enlarged view

Fig.

The CMP sensor contains a Hall-effect device that provides cylinder identification to the Powertrain Control Module (PCM). The sensor generates pulses as groups of notches on the camshaft sprocket pass underneath it. The PCM keeps track of crankshaft rotation and identifies each cylinder by the pulses generated by the notches on the camshaft sprocket. Crankshaft pulses follow each group of camshaft pulses.

The Powertrain Control Module (PCM) sends approximately 5 volts to the Hall-effect sensor. This voltage is required to operate the Hall-effect chip and the electronics inside the sensor. The input to the PCM occurs on a 5 volt output reference circuit. A ground for the sensor is provided through the sensor return circuit. The PCM identifies camshaft position by registering the change from 5 to 0 volts, as signaled from the camshaft position sensor.

The PCM determines fuel injection synchronization and cylinder identification from inputs provided by the camshaft position sensor and crankshaft position sensor. From the two inputs, the PCM determines crankshaft position.

Removal & Installation



  1. The camshaft position sensor is mounted in the front of the head.
  2.  
  3. Disconnect electrical connector from sensor.
  4.  
  5. Remove camshaft position sensor screw.
  6.  
  7. Without pulling on the connector, pull the sensor out of the chain case cover.
  8.  

To Install:

  1. Install sensor in the chain case cover and push sensor in until contact is made with the boss on the head.
  2.  
  3. While holding the sensor in this position, install and tighten the retaining bolt to 12 Nm (105 inch lbs.) torque.
  4.  
  5. Attach electrical connector to sensor.
  6.  
  7. Install the sensor.
  8.  

  1. The camshaft position sensor is mounted in the front of the head.
  2.  
  3. Disconnect electrical connector from sensor.
  4.  
  5. Remove camshaft position sensor screw.
  6.  
  7. Without pulling on the connector, pull the sensor out of the chain case cover.
  8.  

To Install:

  1. Install sensor in the chain case cover and push sensor in until contact is made with the boss on the head.
  2.  
  3. While holding the sensor in this position, install and tighten the retaining bolt to 12 Nm (105 inch lbs.) torque.
  4.  
  5. Attach electrical connector to sensor.
  6.  
  7. Install the sensor.
  8.  

2.4L Engines
  1. Before servicing the vehicle, refer to the Precautions Section.
  2.  
  3. Remove the negative battery cable.
  4.  
  5. Disconnect the PCV hose and reposition.
  6.  
  7. Disconnect the electrical connectors from the Camshaft Position (CMP) sensor.
  8.  
  9. Remove the CMP sensor mounting screws.
  10.  
  11. Remove the CMP sensor.
  12.  
  13. Loosen the screw attaching the target magnet to the rear of the camshaft and remove the magnet.
  14.  

To install:


NOTE
The target magnet has locating dowels that fit into machined locating holes in the end of the camshaft.

  1. Install the target magnet in the end of the camshaft. Tighten the mounting screw to 27 inch lbs. (3 Nm).
    NOTE
    Over-tightening could cause cracks in the magnet. If the magnet cracks, replace it.

  2.  
  3. Install the CMP sensor. Tighten the sensor mounting screws to 115 inch lbs. (13 Nm) torque.
  4.  
  5. Carefully attach the electrical connector to the CMP sensor. Installation at an angle may damage the sensor pins.
  6.  
  7. Connect the PCV Valve hose.
  8.  
  9. Connect the negative battery cable.
  10.  

2.7L Engine
  1. Before servicing the vehicle, refer to the Precautions Section.
  2.  
  3. Disconnect the electrical connector from the Camshaft Position (CMP) sensor.
  4.  
  5. Remove the CMP sensor screw.
  6.  
  7. Without pulling on the connector, pull the CMP sensor out of the chain case cover.
  8.  

To install:

  1. Install the CMP sensor in the chain case cover and push the sensor in until contact is made with the boss on the head. While holding the CMP sensor in this position, install and tighten the retaining bolt to 106 inch lbs. (12 Nm) torque.
  2.  
  3. Attach the electrical connector to the CMP sensor.
  4.  

Testing



Not for Dodge Stratus Sedan

  1. Disconnect the camshaft position sensor connector, and connect the test harness special tool (MB991709) in between. (All terminals should be connected.)
  2.  
  3. Connect the oscilloscope probe to camshaft position sensor connector terminal 2.
  4.  
  5. Disconnect the crankshaft position sensor connector, and connect the test harness special tool (MD998478) in between.
  6.  
  7. Connect the oscilloscope probe to crankshaft position sensor connector terminal 2 (black clip of special tool).
  8.  

When metal aligns with the sensor, voltage goes low (less than 0.3 volts). When a notch aligns with the sensor, voltage spikes high (5.0 volts). As a group of notches pass under the sensor, the voltage switches from low (metal) to high (notch) then back to low. The number of notches determines the amount of pulses. If available, an oscilloscope or scan tool with special module can display the square wave patterns of each timing event.

Click image to see an enlarged view

Fig. Camshaft Position Sensor Testing



Click image to see an enlarged view

Fig. Camshaft Position Sensor Location on 2.7L

Not for Dodge Stratus Sedan

Prior to Testing, ensure the shift selector in Park and block the drive wheels for safety.

Testing the CMP Sensor with a DVOM

This test is used to monitor the DC voltage to look for circuit or sensor faults. If the CMP sensor transistor switches, but cannot pull the signal to ground, the average DC voltage displayed will jump significantly. If the transistor stops switching, the average DC voltage will drop. Because the average voltage is already near 0v, this type of failure is more difficult to find with this test.

Connect the DVOM positive lead to the CMP sensor signal circuit (TN/YL wire) at Pin 1-33 and the negative lead to the battery negative post.

In this example, the display shows the CMP sensor signal at Hot Idle. The DVOM shows a CMP signal of only 0.46v DC because the instrument is averaging the signal voltage. The average value is low because the signal is low much longer than is high (note the 92.1 % duty cycle). Use the DVOM MIN/MAX feature, if available, to verify that the CMP signal is switching from 0-5v.

Note the HZ value in this example is OL. The frequency (Hz) measured by the DVOM could be a useful indicator of an intermittent signal. However, the frequency changes in relation to the camshaft position (number of windows) and can cause the DVOM to be unable to calculate a value. In this case, change the time base from 10 ms/division to 50 or 100 ms/division to have a better chance of seeing a stable and useful value.

Using a Lab Scope to Test the CMP Sensor

The lab scope test is used to monitor this signal over time to verify that the transistor in the sensor continues to toggle the signal from 0-5 volts. Watch for unwanted toggling, failure of the transistor to pull the signal all the way to ground, or intermittently missing one or more pulses. All of these failures can cause drivability problems, trouble codes and no start conditions, depending on the severity of the failure.

The Lab Scope can be used to test the CMP sensor circuit as it provides a very accurate view of circuit activity and any signal glitches. Place the shift selector in Park and block the drive wheels for safety.

Click image to see an enlarged view

Fig.

Connect the Channel A positive probe to the CMP sensor circuit (TN/YL wire) at PCM Pin 1-33, and the negative probe to the battery negative post. Lab Scope Test Example

In the example, the trace shows the CMP sensor signal at Hot Idle. The trace represents 720 of crankshaft rotation, or 360 of camshaft rotation. All six (6) CMP pulses can be seen, in order (1, 2, 3, 1, 3, and 2).

Each group of CMP pulses (1, 2, or 3 pulses) tells the PCM which cylinder is approaching TDC next. The PCM then starts a countdown to TDC using the CKP pulses.

Click image to see an enlarged view

Fig.

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

Visually check the connector, making sure it is attached properly and that all of the terminals are straight, tight and free of corrosion. The output voltage of a properly operating camshaft 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.

  1. Disconnect the camshaft position sensor connector, and connect the test harness special tool (MB991709) in between. (All terminals should be connected.)
  2.  
  3. Connect the oscilloscope probe to camshaft position sensor connector terminal 2.
  4.  
  5. Disconnect the crankshaft position sensor connector, and connect the test harness special tool (MD998478) in between.
  6.  
  7. Connect the oscilloscope probe to crankshaft position sensor connector terminal 2 (black clip of special tool).
  8.  

When metal aligns with the sensor, voltage goes low (less than 0.3 volts). When a notch aligns with the sensor, voltage spikes high (5.0 volts). As a group of notches pass under the sensor, the voltage switches from low (metal) to high (notch) then back to low. The number of notches determines the amount of pulses. If available, an oscilloscope or scan tool with special module can display the square wave patterns of each timing event.

Click image to see an enlarged view

Fig.



Click image to see an enlarged view

Fig.

Prior to Testing, ensure the shift selector in Park and block the drive wheels for safety.

Testing the CMP Sensor with a DVOM

This test is used to monitor the DC voltage to look for circuit or sensor faults. If the CMP sensor transistor switches, but cannot pull the signal to ground, the average DC voltage displayed will jump significantly. If the transistor stops switching, the average DC voltage will drop. Because the average voltage is already near 0v, this type of failure is more difficult to find with this test.

Connect the DVOM positive lead to the CMP sensor signal circuit (TN/YL wire) at Pin 1-33 and the negative lead to the battery negative post.

In this example, the display shows the CMP sensor signal at Hot Idle. The DVOM shows a CMP signal of only 0.46v DC because the instrument is averaging the signal voltage. The average value is low because the signal is low much longer than is high (note the 92.1 % duty cycle). Use the DVOM MIN/MAX feature, if available, to verify that the CMP signal is switching from 0-5v.

Note the HZ value in this example is OL. The frequency (Hz) measured by the DVOM could be a useful indicator of an intermittent signal. However, the frequency changes in relation to the camshaft position (number of windows) and can cause the DVOM to be unable to calculate a value. In this case, change the time base from 10 ms/division to 50 or 100 ms/division to have a better chance of seeing a stable and useful value.

Using a Lab Scope to Test the CMP Sensor

The lab scope test is used to monitor this signal over time to verify that the transistor in the sensor continues to toggle the signal from 0-5 volts. Watch for unwanted toggling, failure of the transistor to pull the signal all the way to ground, or intermittently missing one or more pulses. All of these failures can cause drivability problems, trouble codes and no start conditions, depending on the severity of the failure.

The Lab Scope can be used to test the CMP sensor circuit as it provides a very accurate view of circuit activity and any signal glitches. Place the shift selector in Park and block the drive wheels for safety.

Click image to see an enlarged view

Fig.

Connect the Channel A positive probe to the CMP sensor circuit (TN/YL wire) at PCM Pin 1-33, and the negative probe to the battery negative post. Lab Scope Test Example

In the example, the trace shows the CMP sensor signal at Hot Idle. The trace represents 720 of crankshaft rotation, or 360 of camshaft rotation. All six (6) CMP pulses can be seen, in order (1, 2, 3, 1, 3, and 2).

Each group of CMP pulses (1, 2, or 3 pulses) tells the PCM which cylinder is approaching TDC next. The PCM then starts a countdown to TDC using the CKP pulses.

Click image to see an enlarged view

Fig.

  1. Using the wiring diagram/schematic as a guide, inspect the wiring and connectors between the Camshaft Position (CMP) sensor and the Powertrain Control Module (PCM).
  2.  
  3. Look for any chafed, pierced, pinched, or partially broken wires.
  4.  
  5. Look for broken, bent, pushed out, or corroded terminals.
  6.  
  7. Inspect the CMP sensor for conditions such as loose mounting screws, damage, or cracks.
  8.  
  9. If no other problems are found, remove the CMP sensor.
  10.  
  11. Inspect the CMP sensor and mounting area for any condition that would result in an incorrect signal, such as damage, foreign material, or excessive movement.
  12.  
  13. Using a diagnostic scan tool, check for the presence of any Diagnostic Trouble Codes (DTC-s). Record and address these codes as necessary.
  14.  
  15. If no codes are present, review the scan tool environmental data. If possible, try to duplicate the conditions under which the DTC set.
  16.  
  17. If applicable, actuate the component with the scan tool.
  18.  
  19. Monitor the scan tool data relative to this circuit and wiggle test the wiring and connectors.
  20.  
  21. Look for the data to change, the actuation to be interrupted, or for the DTC to reset during the wiggle test.
  22.  
  23. Refer to any Technical Service Bulletins (TSBs) that may apply.
  24.  
  25. Turn the ignition off.
  26.  
  27. Visually inspect the related wire harness. Disconnect all the related harness connectors. Look for any chafed, pierced, pinched, partially broken wires and broken, bent, pushed out, or corroded terminals.
  28.  
  29. Perform a voltage drop test on the related circuits between the suspected component and the Powertrain Control Module (PCM).
  30.  
  31. Inspect and clean all PCM, engine, and chassis grounds that are related to the most current DTC.
  32.  
  33. If numerous trouble codes were set, use a schematic and inspect any common ground or supply circuits.
  34.  
  35. For intermittent Misfire DTC-s check for restrictions in the Intake and Exhaust system, proper installation of Sensors, vacuum leaks, and binding components that are run by the accessory drive belt.
  36.  
  37. Use the scan tool to perform a System Test if one applies to the component.
  38.  
  39. A co-pilot, data recorder, and/or lab scope should be used to help diagnose intermittent conditions.
  40.  

 
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