Ignition Coil Secondary
2012 Ford F-150 · 5.0L V8 Coyote
Sensor Type
inductive
Waveform Type
pulse-width
Location
Coil-on-plug assembly, secondary output connected directly to spark plug (no plug wire)
Pins
Unknown
Idle Frequency
13.3 Hz
Timebase
5ms/div
Voltage Scale
5kV/div
Trigger
2kV, rising edge
Wiring
N/A - internal connection to spark plug via spring terminal inside coil boot
Expected Voltage Range
At Idle
0V to 25000V
At Higher RPM
0V to 35000V
Expected Pattern
Firing spike to 8-15kV, spark line at 1.5-3kV for 1-2ms duration, followed by coil oscillations. Requires capacitive pickup or inductive clamp adapter.
Known-Good Waveform
Sharp firing line rising vertically to 8-15kV (higher under load), horizontal spark line at 1.5-3kV maintained for 1-2ms burn time, then spark line drops to zero followed by 3-6 coil oscillations decreasing in amplitude. Clean, consistent pattern cylinder-to-cylinder indicates good compression and mixture quality.
Common Failure Patterns
Firing voltage exceeds 20kV at idle, extended spark line voltage above 4kV
Cause: Worn spark plug with excessive gap (common issue with OE Motorcraft plugs beyond 60k miles), lean mixture, or high resistance in secondary circuit
Short or absent spark line, immediate transition to oscillations
Cause: Fouled spark plug, cracked coil boot allowing spark to short to ground, or carbon tracking inside coil
Related DTCs: P030X
Diagnostic Tips
Use a secondary ignition pickup adapter that clamps around the coil body near the spark plug boot. Compare all 8 cylinders - Ford Coyote engines should show very consistent secondary patterns. Uneven patterns often indicate worn spark plugs rather than coil failure.
Related Diagnostic Trouble Codes
P0300P0301P0302P0303
Always confirm waveform data with your vehicle's OEM service manual before diagnosing.
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