Nissan Sentra/Pulsar/NX 1982-1996 Repair Guide

Speed Sensor

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DESCRIPTION



The speed of the front and rear wheels is monitored by the speed sensors. A toothed wheel rotates in front of the sensor generating a small AC voltage which is transmitted to the ABS ECU. The ECU compares the signals and reacts to rapid loss of wheel speed at a particular wheel by engaging the ABS system. Each speed sensor is individually removable. In most cases, the toothed wheels may be replaced if damaged, but disassembly of other components such as hub and knuckle, constant velocity joints, axles or the final drive unit may be required.

TESTING



  1. Disconnect the negative battery cable.
  2.  
  3. Raise and safely support the vehicle.
  4.  
  5. Disconnect the sensor wire connector.
  6.  
  7. Connect a meter set to the 5 volt AC scale between the terminals of the sensor connector.
  8.  
  9. Spin the wheel at approximately 1 revolution per second (60 rpm).
  10.  
  11. Verify the sensor produces a voltage of 0.25-3.00 volts AC.
  12.  
  13. Set the meter to the ohms scale and measure the resistance across the speed sensor.
  14.  
  15. Verify the resistance is as follows:

    1993-94 Vehicles-0.8-1.30 kilo-ohms
     
    1995-96 Vehicles-0.8-1.20 kilo-ohms
     

  16.  

  1. Next, verify the sensor is not grounded by connecting one lead of the ohmmeter to the sensor and the other lead to a ground. Then check the other pin on the sensor connector.
  2.  
  3. Verify there is NO continuity between either pin and ground at the sensor. If not as specified, replace the wheel speed sensor.
  4.  

If the sensor fails the A/C voltage test, inspect the axle and bearing assembly for vibration, the toothed sensor wheel for cracks or missing teeth.

  1. Lower the vehicle and connect the negative battery cable. Reconnect the wheel speed sensor.
  2.  

REMOVAL & INSTALLATION



Front Wheel Speed Sensor

See Figures 1 and 2



Click image to see an enlarged view

Fig. Fig. 1: Front wheel speed sensor mounting-1991-94 vehicles



Click image to see an enlarged view

Fig. Fig. 2: Front wheel speed sensor mounting-1995-96 vehicles

  1. Raise and safely support the front of the vehicle.
  2.  
  3. Remove the tire and wheel.
  4.  
  5. On some models, it may be necessary to remove the inner fender liner.
  6.  
  7. With the ignition switch OFF , disconnect the wheel speed sensor lead from the ABS harness. Remove any retaining bolts or clips holding the harness in place.
  8.  

Clips and retainers must be reinstalled in their exact original location. Take careful note of the position of each retainer and of the correct harness routing during removal.

  1. Remove the bolt(s) holding the speed sensor.
  2.  
  3. Carefully remove the sensor straight out of its mount. Do not subject the sensor to shock or vibration; protect the tip of the sensor at all times.
  4.  

To install:
  1. Fit the sensor into position. Make certain the sensor sits flush against the mounting surface, it must not be crooked.
  2.  
  3. Install the retaining bolt(s). Torque the mounting bolts as follows:

    1991-94 vehicles-96-132 inch lbs. (11-15 Nm)
     
    1995-96 vehicles-13-17 ft. lbs. (18-24 Nm)
     

  4.  

  1. Route the sensor cable correctly and install the harness clips and retainers. The cable must be in its original position and completely clear of moving components. Tighten the clip retaining bolts to 15 ft. lbs. (20 Nm).
  2.  
  3. Connect the sensor cable to the ABS harness.
  4.  
  5. Install the inner fender liner if it was removed.
  6.  
  7. Install the wheel and tire.
  8.  
  9. Lower the vehicle to the ground.
  10.  

Rear Wheel Speed Sensor

See Figures 3 and 4



Click image to see an enlarged view

Fig. Fig. 3: Rear wheel speed sensor mounting-1991-94 vehicles



Click image to see an enlarged view

Fig. Fig. 4: Rear wheel speed sensor mounting-1995-96 vehicles

  1. Raise and safely support the rear of the vehicle.
  2.  
  3. Remove the tire and wheel.
  4.  
  5. With the ignition switch OFF , disconnect the wheel speed sensor lead from the ABS harness. Remove any retaining bolts or clips holding the harness in place.
  6.  

Clips and retainers must be reinstalled in their exact original location. Take careful note of the position of each retainer and of the correct harness routing during removal.

  1. Remove the single bolt holding the speed sensor.
  2.  
  3. Carefully remove the sensor straight out of its mount. Do not subject the sensor to shock or vibration; protect the tip of the sensor at all times.
  4.  

To install:
  1. Fit the sensor into position. Make certain the sensor sits flush against the mounting surface; it must not be crooked.
  2.  
  3. Install the retaining bolt(s). Torque the mounting bolts as follows:

    1991-94 vehicles-96-132 inch lbs. (11-15 Nm)
     
    1995-96 vehicles-18-25 ft. lbs. (25-33 Nm)
     

  4.  

  1. Route the sensor cable correctly and install the harness clips and retainers. The cable must be in its original position and completely clear of moving components. Tighten the clip retaining bolts to 15 ft. lbs. (20 Nm).
  2.  
  3. Connect the sensor cable to the ABS harness.
  4.  
  5. Install the inner fender liner if it was removed.
  6.  
  7. Install the wheel and tire.
  8.  
  9. Lower the vehicle to the ground.
  10.  

 
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