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DTC codes / Chrysler codes / P1366

P1366 · ChryslerIC Cylinder 6 Not Toggling After Enable

P1366 on Chrysler vehicles means the powertrain control module (PCM) has commanded the ignition coil for cylinder 6 to fire, but the coil's feedback circuit is not toggling between high and low voltage as expected. The PCM detects this by monitoring the ignition control (IC) circuit for a change in state after the coil is enabled, and it sets the code when the signal stays static.

SystemPowertrain
Code typeChrysler specific
SeverityMedium
Fix difficultyIntermediate
AreaIgnition system and misfire

Symptoms you may notice

  • Check engine light illuminated, often with no other noticeable symptoms
  • Rough idle or a noticeable vibration that feels like a misfire
  • Engine stumble or hesitation during acceleration
  • Reduced power and poor fuel economy
  • In some cases, a flashing check engine light if the misfire is severe enough to damage the catalytic converter

Common causes, most likely first

  1. Faulty ignition coil on cylinder 6 (open or shorted primary winding)
  2. Damaged or corroded wiring or connector at the cylinder 6 coil
  3. Open or shorted IC control circuit between the PCM and the coil
  4. Failed PCM driver for the cylinder 6 ignition coil
  5. Poor ground connection for the ignition coil circuit
  6. Spark plug or spark plug boot issue that stresses the coil and affects feedback

How to diagnose and fix it

  1. Scan all modules for stored and pending codes, and record freeze-frame data to confirm the fault is present on cylinder 6
  2. Inspect the cylinder 6 ignition coil connector and wiring for corrosion, chafing, or loose pins
  3. Swap the cylinder 6 ignition coil with a known-good coil from another cylinder and see if the code follows the coil
  4. Check the IC control circuit for continuity and short to ground or power using a wiring diagram and multimeter
  5. Verify the coil ground circuit and power feed with a test light or multimeter under load
  6. If the coil and wiring test good, use a lab scope to check the IC signal from the PCM for proper toggling
  7. Replace the PCM only after all other circuits and components have been ruled out

Why cylinder 6 coil codes mislead

  • A coil that fires but has a weak feedback signal can set P1366 without causing a noticeable misfire, so the code does not always mean the coil is dead.
  • Corrosion inside the coil connector is a common cause that is missed when technicians only replace the coil without inspecting the harness.
  • The PCM driver for the ignition coil can fail intermittently, so the code may not reappear immediately after clearing; a wiggle test on the harness can help expose it.
  • Swapping coils between cylinders is the quickest way to confirm whether the fault is the coil or the control circuit, but the code must be cleared and the engine run long enough to re-enable the circuit.
  • A faulty spark plug or excessive gap can stress the coil and cause the feedback signal to drop out, so always inspect the plug on cylinder 6 before condemning the coil.

Can I keep driving with P1366?

You can usually drive the vehicle with P1366 set, but avoid heavy acceleration or towing until the fault is repaired, because a persistent misfire can overheat and damage the catalytic converter. If the check engine light is flashing, stop driving and have the vehicle towed.

Tools that help

Tools we recommend are in the Auto Veteran shop on Amazon. As an Amazon Associate we earn from qualifying purchases.

Guidance is general and written for Chrysler vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.

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