Inspection Using An Oscilloscope (Reference)

Cooling fan control 

PCM terminals 

• 1 R (+)-body ground (-)

Oscilloscope setting 

• 5 V/DIV (Y), 20 ms/DIV (X), DC range

Vehicle condition 

• Idle after warm up
  Fig 1: Identifying Signal Waveform

  Courtesy of MAZDA MOTORS CORP.

APP sensor No. 2 signal 

Accelerator pedal released 

Accelerator pedal depressed 

PCM terminals 

• 1AO (+)-body ground (-)

Oscilloscope setting 

• 2.5 V/DIV (Y), 2 ms/DIV (X), DC range

Vehicle condition 

• Turn the ignition switch to the ON position.
  Fig 3: Identifying Signal Waveform

  Courtesy of MAZDA MOTORS CORP.

Purge control 

PCM terminals 

1 BA (+)-body ground (-) 

Oscilloscope setting 

10 V/DIV (Y), 20 ms/DIV (X), DC range 

Vehicle condition 

Idle after warm up 

A/F sensor heater control 

PCM terminals 

2A (+)-body ground (-) 

Oscilloscope setting 

5 V/DIV (Y), 200 ms/DIV (X), DC range 

Vehicle condition 

Idle (immediately after starting the engine) 

HO2S heater control 

PCM terminals 

2B (+)-body ground (-) 

Oscilloscope setting 

5 V/DIV (Y), 1 s/DIV (X), DC range 

Vehicle condition 

Idle (immediately after starting the engine) 

OCV control signal 

PCM terminals 

2E (+)-body ground (-) 

Oscilloscope setting 

2 V/DIV (Y), 0.8 ms/DIV (X), DC range 

Vehicle condition 

Idle after warm up 

IGT1, IGT2, IGT3, IGT4 control 

PCM terminals 

IGT1 (ignition coil No. 1): 2G (+)-body ground (-) 

IGT2(ignition coil No. 2): 2K (+)-body ground (-) 

IGT3(ignition coil No. 3): 2L (+)-body ground (-) 

IGT4(ignition coil No. 4): 2H (+)-body ground (-) 

Oscilloscope setting 

1 V/DIV (Y), 50 ms/DIV (X), DC range 

Vehicle condition 

• Idle after warm up

CMP signal 

PCM terminals 

2S (+)-body ground (-) 

Oscilloscope setting 

1 V/DIV (Y), 25 ms/DIV (X), DC range 

Vehicle condition 

Idle after warm up 

CKP signal 

PCM terminals 

2W (+)-body ground (-) 

Oscilloscope setting 

1 V/DIV (Y), 5 ms/DIV (X), DC range 

Vehicle condition 

Idle after warm up 

Generator field coil control 

PCM terminals 

2AA (+)-body ground (-) 

Oscilloscope setting 

0.5 V/DIV (Y), 2 ms/DIV (X), DC range 

Vehicle condition 

Idle after warm up 

Generator output voltage 

PCM terminals 

2AF (+)-body ground (-) 

Oscilloscope setting 

2 V/DIV (Y), 2 ms/DIV (X), DC range 

Vehicle condition 

Idle after warm up 

Fuel injection (#1, #2, #3, #4) control 

PCM terminals 

Fuel Injection No. 1: 2BB (+)-body ground (-) 

Fuel Injection No. 2: 2BC (+)-body ground (-) 

Fuel Injection No. 3: 2BD (+)-body ground (-) 

Fuel Injection No. 4: 2AZ (+)-body ground (-) 

Oscilloscope setting 

10 V/DIV (Y), 25 ms/DIV (X), DC range 

Vehicle condition 

Idle after warm up