Forenza 2007

Vehicle Speed Sensor

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Operation



Specific to:

Suzuki Forenza 2007-2008

Suzuki Reno 2007-2008

Vehicle speed information is provided to the Engine Control Module (ECM) by the Vehicle Speed Sensor (VSS). The VSS is a permanent magnet generator that is mounted in the transaxle and produces a pulsing voltage whenever vehicle speed is over 3 mph (5 km/h). The Alternating Current (AC) voltage level and the number of pulses increases with vehicle speed. The ECM converts the pulsing voltage into mph (km/h) and then supplies the necessary signal to the instrument panel for speedometer/odometer operation and to the cruise control module and multi-function alarm module operation. This Diagnostic Trouble Code (DTC) will detect if vehicle speed is reasonable according to engine RPM and load. The permanent magnet generator only produces a signal if the drive wheels are turning greater than 5 mph (8 km/h).

Removal & Installation



Specific to:

Suzuki Forenza 2007-2008

Suzuki Reno 2007-2008

  1. Disconnect the speedometer speed sensor electrical connector.

    Click image to see an enlarged view

    Fig. Vehicle Speed Sensor (VSS)

  2.  
  3. Remove the speedometer housing retaining bolt.
  4.  
  5. Remove the speedometer-driven gear and the speedometer housing.

    Click image to see an enlarged view

    Fig. VSS removal

  6.  

To install:

  1. Coat the O-ring with petroleum jelly.
  2.  
  3. Install the speedometer-driven gear and the speedometer housing.
  4.  
  5. Install the speedometer housing retaining bolt.
  6.  
  7. Tighten the speedometer housing retaining bolt to 35 inch lbs. (4 Nm).
  8.  
  9. Connect the speedometer speed sensor electrical connector.
  10.  

Testing



Specific to:

Suzuki Forenza 2007-2008

Suzuki Reno 2007-2008

The permanent magnet generator only produces a signal if the drive wheels are turning greater than 5 mph (8 km/h).


NOTE
Proper engine loads cannot be achieved in a shop environment to properly run the vehicle within the Freeze Frame Data conditions. It will be necessary to drive the vehicle on the road to obtain the proper engine loads. This step verifies that the ECM is receiving a signal from the vehicle speed sensor.



Click image to see an enlarged view

Fig. Vehicle Speed Sensor (VSS) schematic

  1. A resistance reading that is higher than the specified value indicates that the VSS circuitry is open.
  2.  
  3. With the Scan Tool, check that the displayed resistance is less than the 1300 ohms, if so, the VSS high and low circuits are shorted together.
  4.  
  5. This checks the resistance of the VSS if no opens or shorts were found on the VSS high and low circuit.
  6.  

Power Test with Scan Tool.



The RPM is between 2,500 and 4,000 rpm
 
Throttle Position (TP) sensor is between 25 and 60%
 
Manifold Absolute Pressure (MAP) is greater than 8.7 psi (60 kPa)
 

Deceleration Test with Scan Tool.



Manifold Absolute Pressure (MAP) is less than 4.4 psi (30 kPa)
 
Change in RPM/cycle is greater than 50 rpm/ cycle
 
Throttle Position (TP) sensor is less than 0.8%
 
The RPM is between 1,800-6,000 rpm
 

 
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