On-Vehicle Inspection

Remove the aerodynamic under cover. (See AERODYNAMIC UNDER COVER REMOVAL/INSTALLATION .)
Inspect the VSS power supply circuit.
1. Remove the insulator from the transaxle.
  
  Fig 1: VSS Insulator And Bolts With Torque Specification
  Courtesy of MAZDA MOTORS CORP.
2. Disconnect the VSS connector.
  
  Fig 2: Identifying Vehicle Speed Sensor
  Courtesy of MAZDA MOTORS CORP.
3. Switch the ignition ON.
4. Measure the voltage at VSS harness-side connector terminal A.
  
  Fig 3: Identifying Vehicle Speed Sensor Harness-Side Connector Terminals
  Courtesy of MAZDA MOTORS CORP.
  - If there is any malfunction in the voltage, repair or replace the power supply circuit wiring harness.
    Voltage
  - B+
5. Switch the ignition OFF.
6. Connect the VSS connector.
Inspect the VSS GND circuit.
1. Switch the ignition OFF.
2. Measure the voltage at VSS terminal C.
  
  Fig 4: Identifying Vehicle Speed Sensor Harness-Side Connector Terminals
  Courtesy of MAZDA MOTORS CORP.
  - If there is any malfunction in the voltage, repair or replace the GND circuit wiring harness.
    Voltage
  - 1.0 V or less
Inspect the VSS signal circuit.
1. Connect the oscilloscope tester lead to the TCM and perform the oscilloscope setting.
  - Terminal: TCM Z (+)-GND (-)
  - Oscilloscope setting: 1 V/DIV (Y), 2 ms/DIV (X), DC range
2. Start the engine.
3. When all of the following conditions are met, measure the generated pulse.
  - Vehicle speed: 30 km/h {19 mph}
  - Gear position: 3GR
    
    Fig 5: Vehicle Speed Sensor Waveform
    Courtesy of MAZDA MOTORS CORP.
  - If there is any malfunction in the generated pulse, replace the VSS. (See VEHICLE SPEED SENSOR (VSS) REMOVAL/INSTALLATION .)