Fuel injection control (-) signal

Courtesy of MAZDA MOTORS CORP.

PCM terminals 

• Fuel Injection No. 1:1DH (+)-body ground (-)
• Fuel Injection No. 2:1CZ (+)-body ground (-)
• Fuel Injection No. 3:1CV (+)-body ground (-)
• Fuel Injection No. 4:1DD (+)-body ground (-)

Oscilloscope setting 

• 10 V/DIV (Y), 5 ms/DIV (X), DC range

Vehicle condition 

• Idle after warm up