Ignition Coil Primary
2021 Toyota RAV4 · 2.5L I4
Sensor Type
inductive
Waveform Type
pulse-width
Location
Individual coil-on-plug assemblies mounted directly on each spark plug, valve cover top
Pins
2-pin connector
Idle Frequency
20 Hz
Timebase
10ms/div
Voltage Scale
50V/div
Trigger
6V, rising edge
Wiring
Black/Yellow (ground), Pink or Light Green (switched 12V ignition signal from ECM)
Expected Voltage Range
At Idle
0V to 14V
At Higher RPM
0V to 14V
Expected Pattern
Square wave with sharp rise to battery voltage, dwell period at 12-14V, then sharp drop to near 0V with brief negative spike to -80V to -120V during coil collapse
Known-Good Waveform
Clean square wave showing 2-4ms dwell time at idle, rising sharply to battery voltage when coil is energized. Upon ECM shutoff, voltage drops with a sharp negative inductive spike to -80V to -120V lasting approximately 200-400 microseconds. Pattern repeats consistently every 120 degrees of crankshaft rotation for this 4-cylinder engine.
Common Failure Patterns
Reduced or absent negative spike below -40V, rounded edges on falling edge
Cause: Weak or failing ignition coil with reduced primary inductance
Diagnostic Tips
The 2019-2024 RAV4 A25A-FKS engine uses individual coil drivers in the ECM. Compare all four cylinders simultaneously to identify cylinder-specific vs. system-wide issues. Check connector C42 at ECM for corrosion on ignition driver circuits.
Related Diagnostic Trouble Codes
P0351P0352P0353P0354
Always confirm waveform data with your vehicle's OEM service manual before diagnosing.
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