Ignition Coil Secondary
2016 Ford F-150 · 5.0L V8 Coyote
Sensor Type
inductive
Waveform Type
pulse-width
Location
Secondary output from coil-on-plug assemblies to spark plug, measured at coil tower or using capacitive pickup
Pins
Unknown
Idle Frequency
20.8 Hz
Timebase
5ms/div
Voltage Scale
5kV/div
Trigger
2kV, rising edge
Wiring
N/A - measured via spark plug boot or capacitive probe
Expected Voltage Range
At Idle
0V to 35000V
At Higher RPM
0V to 40000V
Expected Pattern
Initial firing spike 8-15kV, spark line at 1.5-3kV for 1-2ms duration, followed by coil oscillations and then dwell
Known-Good Waveform
Firing line should show sharp rise to 8-15kV under normal conditions, followed by consistent spark line at 1.5-3kV lasting 1-2ms at idle. Spark line should be relatively flat with minimal fluctuation. Coil oscillations after spark should show 3-5 dampened waves.
Common Failure Patterns
Firing line exceeds 20kV or spark line irregular/absent
Cause: Fouled spark plug, excessive plug gap (over 0.054 inch spec), or carbon tracking in coil boot
Diagnostic Tips
Use capacitive pickup or 100:1 high-voltage probe. Ford Coyote engines use iridium plugs gapped at 0.051-0.057 inches; verify gap before condemning coils. Check for intake manifold vacuum leaks if multiple cylinders show elevated firing voltages.
Related Diagnostic Trouble Codes
P0300P0301P0302P0303
Always confirm waveform data with your vehicle's OEM service manual before diagnosing.
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