Nissan Maxima 1993-1998 Repair Guide

Crankshaft Position Sensor(s)

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OPERATION



The Crankshaft Position Sensor is located on the transaxle housing, facing the gear teeth of the flywheel/flexplate. It detects the fluctuation of the engine revolution. The sensor consists of a permanent magnet, core and coil.

When the engine is running, the high and low parts of the teeth cause the gap with the sensor to change. This changing gap causes the magnetic field near the sensor to change. Due to the changing magnetic field, the voltage from the sensor changes.

The ECM receives this varying voltage signal and detects the fluctuation of the engine revolution.

TESTING



POS Sensor

See Figures 1 and 2



Click image to see an enlarged view

Fig. Fig. 1: Crankshaft position sensor (POS) location detail



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Fig. Fig. 2: Backprobe terminals 2 and 3 as shown; touch the tip with a screwdriver, and then quickly pull away while measuring voltage

  1. Remove the sensor from the engine.
  2.  
  3. Inspect the sensor tip. If damage to the tip is evident, replace the sensor.
  4.  
  5. Plug in the sensor, but do not install it .
  6.  
  7. Backprobe terminals 2 and 3 with a voltmeter. Using a screwdriver, touch it against the sensor core.
  8.  

The voltmeter should read approximately 5 volts.

  1. Slowly pull the screwdriver away; the meter should remain at 5 volts.
  2.  
  3. Touch the sensor core with the screwdriver; then quickly draw it away. The voltage should drop to approximately 0 volts.
  4.  
  5. If the sensor does not respond accordingly, the sensor may be faulty.
  6.  

REF Sensor

See Figures 3 and 4



Click image to see an enlarged view

Fig. Fig. 3: The Crankshaft position sensor (REF) is located next to the crankshaft damper



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Fig. Fig. 4: Measure the resistance between the two terminals to check for proper operation

  1. Measure the resistance between the two terminals on the sensor.
  2.  
  3. Resistance between the terminals should be approximately 470-570 ohms @ 68°F (20°C).
  4.  

REMOVAL & INSTALLATION



POS Sensor

The POS crankshaft position sensor is located on the transaxle housing facing the gear teeth of the flywheel/flexplate.

  1. Disconnect the sensor electrical harness.
  2.  
  3. Remove the sensor mounting bolts.
  4.  
  5. Remove the sensor from the transaxle housing.
  6.  

To install:
  1. Install the sensor in the transaxle housing.
  2.  
  3. Tighten the sensor mounting bolts securely.
  4.  
  5. Connect the sensor electrical harness.
  6.  

REF Sensor

The REF crankshaft position sensor is located on the oil pan, near the crankshaft damper.

  1. Disconnect the sensor electrical harness.
  2.  
  3. Remove the sensor mounting bolts.
  4.  
  5. Remove the sensor from the oil pan.
  6.  

To install:
  1. Install the sensor in the transaxle housing.
  2.  
  3. Tighten the sensor mounting bolts securely.
  4.  
  5. Connect the sensor electrical harness.
  6.  

 
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