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DTC codes / GM codes / P1355

P1355 · GMIC Output High Pulse Detected When Grounded Cyl 5

P1355 on a GM vehicle means the ignition control module (ICM) reported a high-voltage pulse on the cylinder 5 ignition control circuit at a moment when the PCM expected that circuit to be grounded. In plain terms, the computer commanded the coil to charge by pulling the control line low, but the line stayed high, so the PCM flagged an abnormal output state for cylinder 5.

SystemPowertrain
Code typeGM specific
SeverityMedium
Fix difficultyIntermediate
AreaIgnition system and misfire

Symptoms you may notice

  • Illuminated check engine light, often with no other symptoms besides the warning light
  • Noticeable engine misfire or rough running, especially under load or at idle
  • Reduced engine power or a limp-home mode in some GM applications
  • Shaking or vibration felt through the steering wheel and floorboard
  • Worse fuel economy and a strong raw-fuel smell from the exhaust
  • Intermittent misfire that comes and goes with heat or vibration

Common causes, most likely first

  1. Faulty ignition control module (ICM) output driver for the cylinder 5 circuit
  2. Open or chafed wire in the cylinder 5 ignition control circuit between the ICM and PCM
  3. Corroded or loose connector terminal at the ICM or PCM harness
  4. Short to voltage on the cylinder 5 control wire from harness damage or water intrusion
  5. Failed ignition coil for cylinder 5 drawing abnormal current and disturbing the control signal
  6. PCM driver fault on the cylinder 5 control output (less common but possible)
  7. Poor ground connection at the ICM or engine block causing erratic output behavior

How to diagnose and fix it

  1. Scan all modules and record freeze-frame data for P1355 plus any companion misfire codes before touching anything
  2. Inspect the ICM and PCM connectors for corrosion, pushed pins, or water intrusion, then clean and reseat them
  3. Check the cylinder 5 ignition control wire for continuity, shorts to voltage, and shorts to ground with a multimeter
  4. Swap the cylinder 5 coil with a known-good coil from another cylinder and see whether the misfire follows the coil
  5. Back-probe the cylinder 5 control circuit with a lab scope or LED test light to confirm the PCM command and ICM response
  6. Verify ICM ground and power feeds under load, repairing any high-resistance ground or supply connection
  7. Replace the ignition control module only after wiring and coil tests pass, then clear codes and road-test to confirm the repair

What the cylinder 5 control circuit is telling you

  • A high pulse when grounded often points to a wiring short to voltage rather than a failed ICM, so inspect the harness near hot exhaust components before condemning the module.
  • Technicians frequently replace the ICM when the real fault is a chafed control wire inside the loom, so always ohm and load-test the circuit end to end.
  • A weak or failing ignition coil on cylinder 5 can back-feed the control circuit and set P1355 without any visible damage to the coil body.
  • Poor engine ground straps on older GM vehicles cause the ICM to report false high-pulse events, and cleaning the grounds often clears the code.
  • P1355 can appear alongside misfire codes for other cylinders when the fault is a shared ground or supply issue at the ICM rather than a cylinder-specific problem.

Can I keep driving with P1355?

You can drive short distances to a repair shop, but avoid heavy acceleration, towing, and long highway trips because the misfire can overheat the catalytic converter and waste fuel. If the check engine light starts 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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