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DTC codes / GM codes / P1352

P1352 · GMIC Output High Pulse Detected When Grounded Cyl 2

P1352 on a GM vehicle means the ignition control module (ICM) has detected an unexpected high voltage pulse on the cylinder 2 ignition control circuit while that circuit is supposed to be grounded. The computer commanded the coil for cylinder 2 to fire, but the feedback signal showed the circuit stayed high when it should have been pulled low, indicating a fault in the ignition coil, wiring, or ICM itself.

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 quality with noticeable vibration through the steering wheel or seat
  • Illuminated check engine light, sometimes flashing if the misfire is severe
  • Reduced fuel economy and a noticeable loss of power
  • Often no symptoms besides the warning light, particularly if the misfire is intermittent
  • Possible difficulty starting or a stall immediately after startup in severe cases

Common causes, most likely first

  1. Faulty ignition coil for cylinder 2, internally shorted or with excessive resistance
  2. Damaged or chafed wiring between the ICM and the cylinder 2 coil, including a short to voltage
  3. Corroded or loose connector pins at the ICM or coil harness
  4. Failed ignition control module (ICM) driver circuit for cylinder 2
  5. Faulty spark plug or spark plug boot causing abnormal coil feedback
  6. Poor engine ground or ICM ground connection causing erratic signal behavior

How to diagnose and fix it

  1. Inspect the cylinder 2 spark plug and boot for wear, carbon tracking, or damage, and replace if needed
  2. Check the ignition coil for cylinder 2 by swapping it with a known-good coil from another cylinder and seeing if the code moves
  3. Visually inspect the harness and connectors between the ICM and the cylinder 2 coil for chafing, corrosion, or loose pins
  4. Use a multimeter to check for continuity and shorts to voltage on the cylinder 2 ignition control circuit while wiggling the harness
  5. Verify the ICM ground circuit is clean and tight, and measure voltage drop across the ground connection
  6. If wiring and coil test good, test the ICM output signal with an oscilloscope or replace the ICM with a known-good unit
  7. Clear the code and perform a road test to confirm the repair, monitoring misfire counters if available

Before you replace the ignition control module

  • A swapped coil that moves the misfire to another cylinder is the fastest way to rule out the ICM, yet many technicians replace the module first and waste money.
  • The code can be set by a spark plug with a cracked insulator that causes the coil to feedback a high pulse, so always inspect plugs before condemning the coil or ICM.
  • Intermittent P1352 often traces to a chafed wire near the exhaust manifold or a corroded connector that only acts up when hot or wet, so wiggle-test the harness while watching live misfire data.
  • On some GM engines, a failing ignition control module can set P1352 for cylinder 2 even when the coil and wiring are perfect, but the module should be the last suspect after all circuit tests pass.
  • This code does not always mean the engine is misfiring at that moment; a stored history code can be left over from a previous event, so check for pending or active status before tearing into the ignition system.

Can I keep driving with P1352?

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. If the check engine light is flashing, stop driving and have the vehicle towed to prevent converter damage.

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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