Ignition Coil Secondary
2021 Toyota Camry · 2.5L I4 Hybrid
Sensor Type
inductive
Waveform Type
pulse-width
Location
Coil-on-plug assemblies mounted directly on spark plugs, cylinder head top
Pins
Unknown
Idle Frequency
16.7 Hz
Timebase
5ms/div
Voltage Scale
5kV/div
Trigger
2kV, rising edge
Wiring
N/A - internal high voltage connection to spark plug
Expected Voltage Range
At Idle
0V to 35000V
At Higher RPM
0V to 40000V
Expected Pattern
Initial firing spike 8-15kV, burn time 1.0-1.5ms at 2-4kV with slight downward slope, clean cutoff
Known-Good Waveform
Capacitive coupling measurement shows initial firing spike of 8-15kV depending on load and compression, followed by stable spark line at 2-4kV for 1.0-1.5ms with gradual downward slope. Coil oscillations should be minimal (3-5 oscillations) after spark extinction, indicating good coil and circuit integrity.
Common Failure Patterns
Firing spike above 20kV, short or absent burn time, spark line dropout
Cause: Excessive spark plug gap due to wear, carbon tracking in coil boot, or high secondary resistance
Irregular spark line with voltage fluctuations or multiple restrike events
Cause: Lean air-fuel mixture, vacuum leak, or fouled spark plug causing intermittent ionization path
Diagnostic Tips
Use capacitive pickup or low-capacitance probe on coil housing. Hybrid system runs engine intermittently; capture during extended engine-on period. High compression Atkinson cycle may show higher firing voltages than conventional engines.
Related Diagnostic Trouble Codes
P0300P0301P0302P0303
Always confirm waveform data with your vehicle's OEM service manual before diagnosing.
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