Breeze, Cirrus, Sebring Convertible and Sedan, Stratus Sedan, 1999-2005

Crankshaft Position Sensor

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Operation



The PCM determines what cylinder to fire from the crankshaft position sensor input and the camshaft position sensor input. On 4-cylinder engines, the second crankshaft counterweight has two sets of four timing reference notches, including a 60 signature notch. From the crankshaft position sensor input, the PCM determines engine speed and crankshaft angle (position). On 6-cylinder engines, this sensor is a Hall effect device that detects notches in the flexplate.

The notches generate pulses from high to low in the crankshaft position sensor output voltage. When a metal portion of the notches line up with the crankshaft position sensor, the sensor output voltage goes low (less than 0.5 volts). When a notch aligns with the sensor, voltage goes high (5.0 volts). As a group of notches pass under the sensor, the output voltage switches from low (metal) to high (notch), then back to low.

If available, an oscilloscope can display the square wave patterns of each voltage pulse. From the width of the output voltage pulses, the PCM calculates engine speed. The width of the pulses represents the amount of time the output voltage stays high before switching back to low. The period of time the sensor output voltage stays high before switching back to low is referred to as pulse width. The faster the engine is operating, the smaller the pulse width on the oscilloscope.

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Fig.

On 4-cylinder engines, the crankshaft position sensor is mounted to the engine block behind the alternator, just above the oil filter. On 6-cylinder engines, the crankshaft position sensor is mounted on the transaxle housing, above the vehicle speed sensor. Location of the crankshaft position (CKP) sensor on 2.0L engines

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Fig.



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Fig.



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Fig.



Click image to see an enlarged view

Fig.

Testing



Not for Dodge Stratus Sedan

Testing with DVOM

This test is used to monitor the DC voltage and frequency (HZ) in order to look for circuit or sensor faults. If the transistor switches, but cannot pull the signal to ground, the average DC voltage displayed will jump significantly. Also, the transistor may fail and toggle rapidly, producing a frequency that is not appropriate for the engine rpm.

  1. It is important to monitor these values over time, as many failures occur intermittently.
  2.  
  3. Place the shift selector in Park and block the drive wheels for safety.
  4.  
  5. Connect the DVOM positive lead to the CKP sensor signal circuit (GY/BK wire) at Pin 1-32 and the negative lead to the battery negative post.
  6.  
  7. If the CKP sensor signal is at Hot Idle, the DVOM would show a CKP signal of only 0.48v DC because the tester is averaging the signal voltage. The average value is low because the signal is low much longer than it is high (a duty cycle of 91.5 % may be shown on the DVOM).
  8.  
  9. Use the DVOM MIN/MAX feature, if available, to verify that the CKP signal is really switching from 0-5v.
  10.  

Another way to use the DVOM to test the CKP sensor signal is to observe the frequency of the signal. At hot idle, the DVOM display might show 140.9 Hz. (140.9 cycles per second X 60 seconds / 13 slots per revolution = 650.3 rpm). Using this formula for a no start, it is easy to calculate that at 200 rpm cranking speed, the DVOM should read about 43 Hz.

Click image to see an enlarged view

Fig.

Testing the CKP Sensor with Lab Scope

The lab scope is used to monitor the CKP signal over time to verify that the transistor in the sensor continues to toggle the signal from 0-5 volts at the appropriate frequency. Watch for unwanted toggling, failure of the transistor to pull the signal to ground, or intermittently missing one or more pulses. All of these failures can cause driveability problems, trouble codes and no start conditions, depending on the severity of the failure. The Lab Scope can be used to test the CKP sensor as it provides a very accurate view of the sensor waveform and sensor relationships.

  1. Place the shift selector in Park and block the drive wheels for safety.

    Click image to see an enlarged view

    Fig.

  2.  
  3. Connect the positive lead to the CKP sensor signal circuit (GY/BK wire) at Pin 1-32 and the negative lead to the battery negative post.
  4.  
  5. To make the waveforms as clear as possible, set the scope settings to match the examples
  6.  

To test the CKP 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. Also inspect the notches in the crankshaft (4-cylinder) or flywheel (6-cylinder) for damage, and replace if necessary.

The output voltage of a properly operating 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

Testing with DVOM

This test is used to monitor the DC voltage and frequency (HZ) in order to look for circuit or sensor faults. If the transistor switches, but cannot pull the signal to ground, the average DC voltage displayed will jump significantly. Also, the transistor may fail and toggle rapidly, producing a frequency that is not appropriate for the engine rpm.

  1. It is important to monitor these values over time, as many failures occur intermittently.
  2.  
  3. Place the shift selector in Park and block the drive wheels for safety.
  4.  
  5. Connect the DVOM positive lead to the CKP sensor signal circuit (GY/BK wire) at Pin 1-32 and the negative lead to the battery negative post.
  6.  
  7. If the CKP sensor signal is at Hot Idle, the DVOM would show a CKP signal of only 0.48v DC because the tester is averaging the signal voltage. The average value is low because the signal is low much longer than it is high (a duty cycle of 91.5 % may be shown on the DVOM).
  8.  
  9. Use the DVOM MIN/MAX feature, if available, to verify that the CKP signal is really switching from 0-5v.
  10.  

Another way to use the DVOM to test the CKP sensor signal is to observe the frequency of the signal. At hot idle, the DVOM display might show 140.9 Hz. (140.9 cycles per second X 60 seconds / 13 slots per revolution = 650.3 rpm). Using this formula for a no start, it is easy to calculate that at 200 rpm cranking speed, the DVOM should read about 43 Hz.

Click image to see an enlarged view

Fig.

Testing the CKP Sensor with Lab Scope

The lab scope is used to monitor the CKP signal over time to verify that the transistor in the sensor continues to toggle the signal from 0-5 volts at the appropriate frequency. Watch for unwanted toggling, failure of the transistor to pull the signal to ground, or intermittently missing one or more pulses. All of these failures can cause driveability problems, trouble codes and no start conditions, depending on the severity of the failure. The Lab Scope can be used to test the CKP sensor as it provides a very accurate view of the sensor waveform and sensor relationships.

  1. Place the shift selector in Park and block the drive wheels for safety.

    Click image to see an enlarged view

    Fig.

  2.  
  3. Connect the positive lead to the CKP sensor signal circuit (GY/BK wire) at Pin 1-32 and the negative lead to the battery negative post.
  4.  
  5. To make the waveforms as clear as possible, set the scope settings to match the examples
  6.  

 
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