GM Cavalier/Sunfire 1995-2000 Repair Guide

Vehicle Speed Sensor

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OPERATION



The Vehicle Speed Sensor (VSS) is a magnetic pick-up sensor that sends a signal to the Powertrain Control Module (PCM) and the speedometer. The sensor measures the rotation of the output shaft on the transaxle and sends an AC voltage signal to the PCM which determines the corresponding vehicle speed.

TESTING



  1. To test the VSS, backprobe the VSS terminals with a high impedance voltmeter (set at the AC voltage scale).
  2.  
  3. Safely raise and support the entire vehicle using jackstands. Make absolutely sure the vehicle is stable.
  4.  
  5. Start the vehicle and place it in gear.
  6.  
  7. Verify that the VSS voltage increases as the drive shaft speed increases.
  8.  
  9. If the VSS voltage is not as specified the VSS may be faulty.
  10.  

REMOVAL & INSTALLATION



3T40 Automatic Transaxle

See Figure 1



Click image to see an enlarged view

Fig. Fig. 1: VSS mounting-3T40 transaxle

  1. Raise and safely support the vehicle securely on jackstands.
  2.  
  3. Unplug the electrical connector.
  4.  
  5. Remove the speed sensor housing retaining bolts.
  6.  
  7. Remove the speed sensor from the transaxle case.
  8.  

To install:
  1. Inspect the sensor O-ring for wear, cracks or leakage and replace if necessary.
  2.  
  3. Lubricate the O-ring with some automatic transaxle fluid.
  4.  
  5. Install the O-ring onto the transaxle and place the sensor housing onto the transaxle case.
  6.  
  7. Tighten the retaining bolt to 97 inch lbs. (11 Nm).
  8.  
  9. Attach the electrical connector to the sensor.
  10.  
  11. Lower the vehicle.
  12.  

4T40E Automatic Transaxle

See Figure 2



Click image to see an enlarged view

Fig. Fig. 2: VSS mounting-4T40-E transaxle

  1. Raise and safely support the vehicle securely on jackstands.
  2.  
  3. Unplug the electrical connector.
  4.  
  5. Remove the speed sensor retaining bolt.
  6.  
  7. Remove the speed sensor from the transaxle case.
  8.  

To install:
  1. Inspect the sensor O-ring for wear, cracks or leakage and replace if necessary.
  2.  
  3. Lubricate the O-ring with some automatic transaxle fluid.
  4.  
  5. Install the O-ring onto the sensor and insert the sensor into the transaxle case.
  6.  
  7. Tighten the retaining bolt to 97 inch lbs. (11 Nm).
  8.  
  9. Attach the electrical connector to the sensor.
  10.  
  11. Lower the vehicle.
  12.  

Manual Transaxle

See Figure 3



Click image to see an enlarged view

Fig. Fig. 3: VSS (1) mounting-manual transaxle

  1. Raise and safely support the vehicle securely on jackstands.
  2.  
  3. Unplug the electrical connector.
  4.  
  5. Remove the speed sensor retaining bolt.
  6.  
  7. Remove the speed sensor retainer and remove the speed sensor from the transaxle case.
  8.  

To install:
  1. Inspect the sensor O-ring for wear, cracks or leakage and replace if necessary.
  2.  
  3. Lubricate the O-ring with some Syncromesh® transaxle fluid.
  4.  
  5. Install the O-ring onto the sensor and insert the sensor into the transaxle case.
  6.  
  7. Install the retainer and tighten the retaining bolt to 80 inch lbs. (9 Nm).
  8.  
  9. Attach the electrical connector to the sensor.
  10.  
  11. Lower the vehicle.
  12.  

 
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