Ignition Coil Primary
2017 Toyota Corolla · 1.8L I4
Sensor Type
inductive
Waveform Type
dc-square
Location
Individual coil-on-plug units mounted directly on each spark plug, valve cover top
Pins
2-pin connector
Idle Frequency
25 Hz
Timebase
10ms/div
Voltage Scale
50V/div
Trigger
5V, rising edge
Wiring
Gray/Black (ignition signal from ECM), Black (ground)
Expected Voltage Range
At Idle
0V to 14V
At Higher RPM
0V to 14V
Expected Pattern
Square wave with clean switching, dwell time approximately 3-4ms, followed by inductive kick spike to 80-120V during coil collapse
Known-Good Waveform
Primary should show clean battery voltage during dwell period with sharp drop to ground, followed by negative inductive spike to 80-120V as magnetic field collapses. Dwell time increases slightly with RPM. Current limiting should show flat-top at higher RPM.
Common Failure Patterns
Reduced or missing inductive kick spike below 60V, extended dwell time
Cause: Weak coil with shorted primary windings or failing internal driver transistor
Diagnostic Tips
2ZR-FE engine coils are known for carbon tracking on spark plug side. Check for misfire codes correlating to specific cylinders. Use current probe to verify 5-7 amp primary current draw during dwell.
Related Diagnostic Trouble Codes
P0351P0352P0353P0354
Always confirm waveform data with your vehicle's OEM service manual before diagnosing.
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