Ignition Coil Secondary
2021 Toyota Camry · 2.5L I4
Sensor Type
inductive
Waveform Type
pulse-width
Location
Secondary winding inside coil-on-plug assembly, directly connected to spark plug terminal
Pins
Unknown
Idle Frequency
20.83 Hz
Timebase
5ms/div
Voltage Scale
5kV/div
Trigger
2kV, rising edge
Wiring
No external wiring - internal coil connection to spark plug boot terminal
Expected Voltage Range
At Idle
-500V to 35000V
At Higher RPM
-500V to 40000V
Expected Pattern
Sharp rise to 8000-15000V firing voltage, followed by 1.5-2.5ms spark duration at 2000-3000V burn voltage, then oscillating decay to baseline
Known-Good Waveform
Firing line should spike to 8-15kV (higher when cold), immediately followed by flat spark line at 2-3kV for approximately 1.5-2.5ms duration. Clean oscillating coil ringing follows spark extinction. Spark duration consistency across all four cylinders indicates healthy coils and uniform cylinder compression.
Common Failure Patterns
Firing voltage exceeds 20kV with shortened or absent spark line, excessive coil oscillations
Cause: Open or high resistance spark plug, degraded plug gap, or secondary winding breakdown
Low firing voltage below 5kV with extended spark duration, weak coil ringing
Cause: Fouled spark plug, carbon tracking in coil boot, or compression loss in cylinder
Diagnostic Tips
Use capacitive pickup or inductive clamp around coil boot - never pierce COP coils. Oil contamination in plug wells is common on high-mileage Camry engines; this destroys coil boots and causes arcing. Compare all four cylinders simultaneously to identify outliers.
Related Diagnostic Trouble Codes
P0300P0301P0302P0303
Always confirm waveform data with your vehicle's OEM service manual before diagnosing.
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