Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
2004 Mazda 6 L4-2.3LFACTORY OEM SERVICE PROCEDURE
Oscilloscope Patterns and Waveforms
Inspection Using An Oscilloscope (Reference)

IGT1, IGT2 control signals
PCM terminals
- IGT1 (No.1 and No.4): 1A (+) - 1D (-)
- IGT2 (No.2 and No.3): 1B (+)- 1C (-)
Oscilloscope setting
- 4 V/DIV (Y), 0.01 ms/DIV (X), DC range
Vehicle condition
- Idle after warm up (engine speed approx. 700 rpm, no load, P/S off, A/C off).

Generator output voltage signal PCM terminals
- 1AA (+) - 2AC (-)
Oscilloscope setting
- 2 V/DIV (Y), 2 ms/DIV (X), DC range
Vehicle condition
- Idle after warm up (engine speed approx. 700 rpm, no load, P/S off, A/C off)

HO2S (front) signal
PCM terminals
- 1AB (+) - 2H (-)
Oscilloscope setting
- 0.1 V/DIV (Y), 400 ms/DIV (X), DC range
Vehicle condition
- Idle after warm up (engine speed approx. 700 rpm, no load, P/S off, A/C off)

Generator field coil control signal PCM terminals
- 1AD (+) - 1C (-)
Oscilloscope setting
- 0.5 V/DIV (Y), 1 ms/DIV (X), DC range
Vehicle condition
- Idle after warm up (engine speed approx. 700 rpm, no load, P/S off, A/C off)

CKP sensor signal
(+)
PCM terminals
- 2D (+) - 2H (-)
Oscilloscope setting
- 2 V/DIV (Y), 4 ms/DIV (X), DC range
Vehicle condition
- Idle after warm up (engine speed approx. 700 rpm, no load P/S off, A/C off)

(-)
PCM terminals
- 2G (+) - 2H (-)
Oscilloscope setting
- 2 V/DIV (Y), 4 ms/DIV (X), DC range
Vehicle condition
- Idle after warm up (engine speed approx 700 rpm, no load, P/S off, A/C off)

VSS signal
PCM terminals
- 2I (+) - 2AC (-)
Oscilloscope setting
- 1 V/DIV (Y), 10 ms/DIV (X), DC range
Vehicle condition
- Drive the vehicle with approx 10 km/h {6.2 mph}

CMP sensor signal
(+)
PCM terminals
- 2J (+) - 2H (-)
Oscilloscope setting
- 1 V/DIV (Y), 10 ms/DIV (X), DC range
Vehicle condition
- Idle after warm up (engine speed approx. 700 rpm, no load, P/S off, A/C off)

(-)
PCM terminals
- 2M (+) - 2H (-)
Oscilloscope setting
- 1 V/DIV (Y), 10 ms/DIV (X), DC range
Vehicle condition
- Idle after warm up (engine speed approx. 700 rpm, no load, P/S off, A/C off)

HO2S (front) heater control signal PCM terminals
- 4A (+) - 1C (-)
Oscilloscope setting
- 4 V/DIV (Y), 200 ms/DIV (X), DC range
Vehicle condition
- Idle after warm up (engine speed approx. 700 rpm, no load, P/S off, A/C off)

OCV control signal
PCM terminals
- 4M (+) - 1C (-)
Oscilloscope setting
- 2 V/DIV (Y), 0.8 ms/DIV (X), DC range
Vehicle condition
- Idle after warm up (engine speed approx. 700 rpm, no load, P/S off, A/C off)

Purge control signal PCM terminals
- 4U (+) - 1C (-)
Oscilloscope setting
- 2 V/DIV (Y), 10 ms/DIV (X), DC range
Vehicle condition
- Idle after warm up (engine speed approx 700 rpm, no load, P/S off, A/C off)

Fuel injection control
PCM terminals
- Fuel Injection No.1: 4Z (+) - 1C (-)
- Fuel Injection No.2: 4W (+) - 1C (-)
- Fuel Injection No.3: 4AD (+) - 1C (-)
- Fuel Injection No.4: 4AA (+) - 1C (-)
Oscilloscope setting
- 4 V/DIV (Y) 10 ms/DIV (X), DC range
Vehicle condition
- Idle after warm up (engine speed approx 700 rpm no load, P/S off, A/C off)
IGT1, IGT2 control signals
PCM terminals
- IGT1 (No.1 and No.4): 1A (+) - 1D (-)
- IGT2 (No.2 and No.3): 1B (+)- 1C (-)
Oscilloscope setting
- 4 V/DIV (Y), 0.01 ms/DIV (X), DC range
Vehicle condition
- Idle after warm up (engine speed approx. 700 rpm, no load, P/S off, A/C off).
Generator output voltage signal PCM terminals
- 1AA (+) - 2AC (-)
Oscilloscope setting
- 2 V/DIV (Y), 2 ms/DIV (X), DC range
Vehicle condition
- Idle after warm up (engine speed approx. 700 rpm, no load, P/S off, A/C off)
HO2S (front) signal
PCM terminals
- 1AB (+) - 2H (-)
Oscilloscope setting
- 0.1 V/DIV (Y), 400 ms/DIV (X), DC range
Vehicle condition
- Idle after warm up (engine speed approx. 700 rpm, no load, P/S off, A/C off)
Generator field coil control signal PCM terminals
- 1AD (+) - 1C (-)
Oscilloscope setting
- 0.5 V/DIV (Y), 1 ms/DIV (X), DC range
Vehicle condition
- Idle after warm up (engine speed approx. 700 rpm, no load, P/S off, A/C off)
CKP sensor signal
(+)
PCM terminals
- 2D (+) - 2H (-)
Oscilloscope setting
- 2 V/DIV (Y), 4 ms/DIV (X), DC range
Vehicle condition
- Idle after warm up (engine speed approx. 700 rpm, no load P/S off, A/C off)
(-)
PCM terminals
- 2G (+) - 2H (-)
Oscilloscope setting
- 2 V/DIV (Y), 4 ms/DIV (X), DC range
Vehicle condition
- Idle after warm up (engine speed approx 700 rpm, no load, P/S off, A/C off)
VSS signal
PCM terminals
- 2I (+) - 2AC (-)
Oscilloscope setting
- 1 V/DIV (Y), 10 ms/DIV (X), DC range
Vehicle condition
- Drive the vehicle with approx 10 km/h {6.2 mph}
CMP sensor signal
(+)
PCM terminals
- 2J (+) - 2H (-)
Oscilloscope setting
- 1 V/DIV (Y), 10 ms/DIV (X), DC range
Vehicle condition
- Idle after warm up (engine speed approx. 700 rpm, no load, P/S off, A/C off)
(-)
PCM terminals
- 2M (+) - 2H (-)
Oscilloscope setting
- 1 V/DIV (Y), 10 ms/DIV (X), DC range
Vehicle condition
- Idle after warm up (engine speed approx. 700 rpm, no load, P/S off, A/C off)
HO2S (front) heater control signal PCM terminals
- 4A (+) - 1C (-)
Oscilloscope setting
- 4 V/DIV (Y), 200 ms/DIV (X), DC range
Vehicle condition
- Idle after warm up (engine speed approx. 700 rpm, no load, P/S off, A/C off)
OCV control signal
PCM terminals
- 4M (+) - 1C (-)
Oscilloscope setting
- 2 V/DIV (Y), 0.8 ms/DIV (X), DC range
Vehicle condition
- Idle after warm up (engine speed approx. 700 rpm, no load, P/S off, A/C off)
Purge control signal PCM terminals
- 4U (+) - 1C (-)
Oscilloscope setting
- 2 V/DIV (Y), 10 ms/DIV (X), DC range
Vehicle condition
- Idle after warm up (engine speed approx 700 rpm, no load, P/S off, A/C off)
Fuel injection control
PCM terminals
- Fuel Injection No.1: 4Z (+) - 1C (-)
- Fuel Injection No.2: 4W (+) - 1C (-)
- Fuel Injection No.3: 4AD (+) - 1C (-)
- Fuel Injection No.4: 4AA (+) - 1C (-)
Oscilloscope setting
- 4 V/DIV (Y) 10 ms/DIV (X), DC range
Vehicle condition
- Idle after warm up (engine speed approx 700 rpm no load, P/S off, A/C off)
Factory Service Tools
Use the Manual With the Right Hardware
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- β’ You smell fuel, burning insulation, or see smoke.
- β’ Brakes feel soft, pull hard to one side, or make grinding noises.
- β’ The engine overheats, stalls repeatedly, or misfires under load.
- β’ You are missing required tools, torque specs, or safe lifting equipment.
- β’ You are not confident in the next step or safety outcome.
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