Vehicle speed signal (ATX)

PCM terminals 

• 1J (+)-Negative battery terminal (-)

Oscilloscope setting 

• 1 V/DIV (Y), 2.5 ms/DIV (X), DC range

Vehicle condition 

• Vehicle speed is 32 km/h {20 mph}.
  Fig 1: Inspection Graph Of Vehicle Speed Signal (ATX) Using Oscilloscope

  Courtesy of MAZDA MOTORS CORP.