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P1358

IC Output High Pulse Detected When Grounded Cyl 8.

  • GM
  • Powertrain
  • Manufacturer code
  • Medium severity

How this code is built

P
SystemPowertrain
1
Defined byThe manufacturer
3
AreaIgnition system or misfire
58
FaultThe specific fault in that area

What it means

On GM vehicles P1358 means the powertrain control module has detected a fault in the ignition control (IC) output circuit for cylinder 8. The IC output should be at a low or ground state at certain times, and the module saw a high pulse when that circuit was meant to be grounded. This points to a problem in the ignition control circuit, the ignition module or coil driver, or the related wiring. How the circuit is arranged (distributor, coil packs or coil-on-plug) depends on the model and engine.

Symptoms

  • Check engine light on
  • Misfire or rough running, especially on cylinder 8
  • Hesitation or loss of power under load
  • Hard starting or extended cranking
  • Poor fuel economy
  • Possible fuel smell or flashing warning light if the misfire is severe

Possible causes

  • Wiring fault in the cylinder 8 ignition control circuit (short to voltage, chafing, damaged insulation or corroded connector)likely
  • Faulty ignition module, coil driver or coil for cylinder 8likely
  • Worn or incorrectly gapped spark plug, or damaged plug lead, where fitted, causing abnormal ignition feedbackpossible
  • Poor or missing ground connection for the ignition systempossible
  • Moisture or heat damage at the coil or module connectorpossible
  • Faulty powertrain control module driver circuitrare
  • Outdated or faulty PCM calibration, where the manufacturer has issued an update for this faultrare

How to diagnose

  1. Read all stored and pending codes and note the freeze frame data, including engine speed, load and temperature when the code set.
  2. Check for other ignition or misfire codes, particularly for cylinder 8, to see whether the fault is isolated or wider.
  3. Visually inspect the cylinder 8 coil, module, plug lead and connectors for damage, moisture, corrosion, burning or loose fit.
  4. Inspect the wiring between the ignition module or coil and the PCM for chafing, rubbing against hot or sharp parts, and shorts to voltage.
  5. Check the ignition system power and ground supplies and the condition of the main earth connections.
  6. Remove and inspect the cylinder 8 spark plug for wear, gap, fouling and damage, comparing it with the other cylinders.
  7. Swap the cylinder 8 coil or module with a known good one, where the design allows, and see whether the fault follows it.
  8. Test the IC circuit signal with a scope or multimeter against the manufacturer's specification for your model, and check for a calibration update only after the circuit and components are proven good.

How to fix

  • Repair or replace damaged wiring and connectors in the cylinder 8 ignition control circuit.
  • Replace the faulty ignition coil, ignition module or coil driver once testing confirms it.
  • Fit new spark plugs of the correct specification and gap, and replace any damaged leads.
  • Clean and tighten ignition grounds and repair any corroded earth connections.
  • Update the PCM calibration only where an outdated or faulty calibration is a documented cause, and replace the PCM only after everything else has been ruled out.

Can I keep driving?

Medium severity

The car can usually be driven short distances, but fix it soon because a continuing misfire can overheat and damage the catalytic converter. If the engine is misfiring badly or the warning light is flashing, stop driving and get it checked.

Guide written by AI from the code's definition. Confirm with a diagnosis before replacing parts.

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