CTS 2006-2007, CTS-V 2005-2007, DTS 2006-2007

Vehicle Speed Sensor

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Operation



The Vehicle Speed Sensor or Output Shaft Speed Sensor (VSS)/(OSS) is a magnetic inductive pickup that relays vehicle speed information to the Transmission Control Module (TCM). The TCM uses this information in order to control shift timing, line pressure, and TCC apply and release.

The VSS mounts in the case extension at the vehicle speed sensor reluctor wheel, which is pressed onto the final drive carrier assembly. An air gap of 0.011-0.062 inch. (0.27-1.57 mm) occurs between the sensor and the teeth on the vehicle speed sensor reluctor wheel as the final drive carrier assembly rotates.

The sensor consists of a permanent magnet surrounded by a coil of wire. As the vehicle speed sensor reluctor wheel on the final drive carrier assembly rotates, an AC signal is produced by the VSS. This AC signal consists of a voltage and frequency that changes based on vehicle speed. The TCM uses the frequency portion of this signal to determine vehicle speed. Higher vehicle speeds induce a higher frequency and a higher voltage measurement at the sensor. The voltage portion of the signal is used in diagnostic procedures.

Removal & Installation



Automatic Transmission
  1. Before servicing the vehicle, refer to the Precautions Section.
  2.  
  3. Raise the vehicle.
  4.  
  5. Remove the bolts securing the front transaxle brace to the transaxle and right cylinder head.
  6.  
  7. Remove the electrical connector at the vehicle speed sensor.
  8.  
  9. Remove the retaining bolt and the sensor. Twisting the sensor while pulling outward will aid in removal.
  10.  

To install:

  1. Install the vehicle speed sensor and the retaining bolt. Install a new O-ring seal on sensor if necessary.
  2.  
  3. Tighten the bolt to 89 inch lbs. (10 Nm).
  4.  
  5. Install the electrical connector at the sensor.
  6.  
  7. Install the bolts securing the front transaxle brace to the transaxle and right cylinder head.
  8.  
  9. Lower the vehicle.
  10.  

Manual Transmission
  1. Before servicing the vehicle, refer to the Precautions Section.
  2.  
  3. Remove the transmission support.
  4.  
  5. Lower the rear of the transmission.
  6.  
  7. Disconnect the Vehicle Speed Sensor (VSS) electrical connector.
  8.  
  9. Remove the VSS mounting bolt.
  10.  
  11. Remove the VSS from the rear extension housing.
  12.  

To install:

  1. Install the VSS to the rear extension housing.
  2.  
  3. Install the VSS mounting bolt and tighten to 71 inch lbs. (8 Nm).
  4.  
  5. Connect the VSS electrical connector.
  6.  
  7. Raise the rear of the transmission.
  8.  
  9. Install the transmission support.
  10.  

Testing



  1. Disconnect Vehicle Speed Sensor (VSS/OSS) electrical connector from sensor.
  2.  
  3. With a digital mutimeter check resistance between pin A VSS/OSS low signal and pin B VSS/OSS high signal.
  4.  
  5. Sensor resistance should measure between 1,650-2,200 ohms at 20°C 68°F.
  6.  
  7. If resistance reading is not as stated suspect faulty VSS/OSS sensor.
  8.  
  9. With a digital mutimeter check voltage between pin A VSS low signal and pin B VSS/OSS high signal.
  10.  
  11. Safely lift wheels off of the ground and run in gear to check voltage readings.
  12.  
  13. Check for output voltage this will vary with vehicle speed from a minimum of 0.5 volts AC at 100 RPM to 200 volts at 6,000 RPM.
  14.  
  15. If no voltage reading is present suspect internal transmission problem or faulty VSS/OSS sensor.

    Click image to see an enlarged view

    Fig. Vehicle Speed Sensor (VSS) electrical connector

  16.  

 
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