Nissan Sentra/Pulsar/NX 1982-1996 Repair Guide

Vehicle Speed Sensor

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OPERATION



The vehicle speed sensor provides a vehicle speed signal to the ECM. On conventional speedometers, the speed sensor consists of a reed switch which transforms vehicle speed into a pulse signal. The input received from the sensor is used to regulate ignition timing and decell fuel shut off.

TESTING



See Figure 1



Click image to see an enlarged view

Fig. Fig. 1: With the speedometer cable and cable pinion housing removed, rotate the pinion gear while observing the ohmmeter

  1. Remove the speedometer cable and cable pinion housing, from the transaxle.
  2.  
  3. Disconnect the 20 pin electrical connector from the ECM.
  4.  
  5. Connect an ohmmeter between connector terminal 10 and a known good ground.
  6.  
  7. Turn the ignition switch to the ON position.
  8.  
  9. Observe the ohmmeter while rotating the speedometer drive gear. The reading should fluctuate between continuity and open, twice per revolution.
  10.  
  11. If the sensor did not perform as specified, inspect the wiring between the instrument cluster and the ECM. If the wiring is okay, replace the VSS.
  12.  

REMOVAL & INSTALLATION



The instrument panel mounted VSS is integral part of the vehicle speed sensor. Refer to Chassis Electrical for speedometer head Removal and Installation information.

 
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