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DTC codes / GM codes / P1365

P1365 · GMIC Cylinder 5 Not Toggling After Enable

P1365 on a GM vehicle means the engine control module (ECM) has enabled the ignition control (IC) circuit for cylinder 5 but has not detected the expected voltage toggling on that circuit, indicating an open, short, or faulty component in the cylinder 5 ignition coil control path. The ECM monitors the IC circuit and expects it to switch between high and low states when the ignition coil is commanded to fire; failure to see that toggle sets this code.

SystemPowertrain
Code typeGM specific
SeverityMedium
Fix difficultyIntermediate
AreaIgnition system and misfire

Symptoms you may notice

  • Engine misfire, often felt as a shake or stumble, especially under load or acceleration
  • Rough idle or uneven running
  • Check engine light illuminated, sometimes flashing if the misfire is severe
  • Reduced fuel economy and power output
  • Often no symptoms besides the warning light, particularly if the misfire is intermittent

Common causes, most likely first

  1. Faulty ignition coil for cylinder 5 (open or shorted primary winding)
  2. Damaged or corroded wiring harness or connector at the cylinder 5 ignition coil
  3. Open or shorted IC control circuit between the ECM and the cylinder 5 coil
  4. Poor ground connection for the ignition coil or engine block
  5. Failed engine control module (ECM) driver for the cylinder 5 IC circuit (rare but possible)
  6. Aftermarket or incorrect ignition coil installed previously
  7. Water intrusion or physical damage to the coil or harness

How to diagnose and fix it

  1. Scan all modules for stored codes and record freeze-frame data to confirm the fault conditions
  2. Inspect the cylinder 5 ignition coil and its connector for corrosion, damage, or loose pins
  3. Swap the cylinder 5 ignition coil with a known-good coil from another cylinder and see if the misfire moves
  4. Use a digital multimeter to check resistance of the cylinder 5 coil primary and secondary windings against specifications
  5. Backprobe the IC control circuit at the coil connector and observe the signal with a lab scope or LED test light while cranking or running
  6. Check continuity and resistance of the IC control wire from the ECM to the coil, looking for opens or shorts to ground or power
  7. If all wiring and coils test good, perform a driver test on the ECM circuit or substitute a known-good ECM to rule out internal driver failure

Don't overlook coil driver and ground faults

  • A coil that tests good on a resistance check can still fail under load, so swapping it with another cylinder is often the fastest way to confirm the fault.
  • The IC circuit is a low-current control signal; a poor ground at the coil or engine block can mimic a failed ECM driver and cause this code.
  • Intermittent P1365 often appears only when the engine is hot or vibrating, so wiggle-testing the harness while monitoring the signal is essential.
  • This code does not always mean the coil is bad; a shorted or open control wire between the ECM and coil is a common cause that gets missed.
  • Aftermarket coils with incorrect internal resistance can set this code even when they appear to function, so always compare against OEM specifications.

Can I keep driving with P1365?

You can usually drive the vehicle short distances to a repair shop, but avoid heavy acceleration or towing because a persistent misfire can overheat the catalytic converter and cause costly damage. 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 GM vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.

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