Fuel Injector
2021 Jeep Wrangler · 3.6L V6
Sensor Type
inductive
Waveform Type
pulse-width
Location
Six injectors located in intake manifold runners, fuel rail mounted on intake manifold valley between cylinder banks
Pins
2-pin connector
Idle Frequency
16.67 Hz
Timebase
5ms/div
Voltage Scale
20V/div
Trigger
6V, falling edge
Wiring
Pink/Black (12V constant power from ASD relay), Dark Green/Orange or Dark Green/White (PCM ground pulse control, varies by cylinder)
Expected Voltage Range
At Idle
0V to 60V
At Higher RPM
0V to 70V
Expected Pattern
Square wave showing battery voltage drop to ground during injection pulse, 2.5-4ms pulse width at idle, with inductive kickback spike to 50-70V at pulse end
Known-Good Waveform
Injector waveform should display clean 12-14V baseline dropping sharply to near 0V during the 2.5-4ms injection event at idle. Upon injector closure, expect a sharp inductive kickback spike reaching 50-70V peak, followed by 2-3 damped oscillations. The current ramp during opening should be smooth, reaching peak current in approximately 0.5ms, indicating healthy injector windings with 12-16 ohm resistance.
Common Failure Patterns
Slow or rounded current ramp during opening phase, reduced kickback voltage below 40V
Cause: Increased injector winding resistance due to heat degradation or internal coil damage, elevated leak-off causing rich condition
Pulse width significantly longer than other cylinders (6ms+ at idle) with corresponding rich condition
Cause: Restricted or partially clogged injector reducing flow, PCM compensating with longer pulse, or weak injector spring
Diagnostic Tips
The 3.6L Pentastar uses sequential multi-port injection and is sensitive to injector flow balance. Compare pulse widths between all six cylinders at idle - variation beyond 0.5ms indicates flow imbalance. Check fuel pressure with mechanical gauge as the in-tank pump can fail causing extended pulse widths across all injectors.
Related Diagnostic Trouble Codes
P0200P0201P0202P0203P0204
Always confirm waveform data with your vehicle's OEM service manual before diagnosing.
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