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P1358

IC Output High/Pulse Detected When Grounded Cyl.8.

  • Buick
  • 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 a Buick, P1358 means the engine control module saw an abnormal signal on the ignition control (IC) circuit for cylinder 8. It detected a high output or a pulse on the circuit when it was expected to be grounded or inactive. This points to a fault in the ignition control wiring, the ignition module or coil driver, or the control module itself, rather than a general misfire code.

Symptoms

  • Malfunction indicator lamp on
  • Rough running or misfire, mainly on cylinder 8
  • Hesitation or loss of power under load
  • Hard starting or extended cranking
  • Poor fuel economy
  • Engine running in a reduced-performance or fallback mode

Possible causes

  • Damaged, chafed or shorted ignition control wiring for cylinder 8 (short to voltage or crossed with another circuit)likely
  • Corroded, loose or damaged connector at the coil, ignition module or control module for cylinder 8likely
  • Faulty ignition coil or coil driver for cylinder 8, or a fault in the ignition module on applicable enginespossible
  • Poor ground or low supply voltage to the ignition systempossible
  • Faulty engine control module output driver for the cylinder 8 ignition control circuitrare
  • Outdated or faulty control module calibration, where the manufacturer has a known issue for the modelrare

How to diagnose

  1. Read all stored and pending codes and note the freeze frame data (engine speed, load, temperature, voltage) to see when the fault set.
  2. Check for other ignition or misfire codes, particularly for cylinder 8 or neighbouring cylinders, as they help narrow down a circuit or component fault.
  3. Visually inspect the cylinder 8 coil, ignition module (if fitted), wiring and connectors for chafing, heat damage, corrosion, moisture or bent pins.
  4. Check battery condition, charging voltage and the main engine and ignition grounds for good connections.
  5. Check the ignition control circuit for cylinder 8 for short to voltage, short to ground, or crossing with other circuits, following the wiring diagram for the specific model and engine.
  6. Swap the cylinder 8 coil or driver with a known good cylinder, clear the codes and see if the fault follows the component.
  7. Check the ignition feed and control signals with a suitable meter or scope while cranking, as the layout varies by engine.
  8. Check for known calibration updates for the model and engine before considering control module replacement.

How to fix

  • Repair or replace damaged ignition control wiring for cylinder 8 and secure it away from heat and abrasion.
  • Clean, repair or replace corroded or damaged connectors and terminals.
  • Replace the faulty ignition coil, coil driver or ignition module found to be at fault.
  • Restore good battery, supply and ground connections.
  • Replace or reprogram the engine control module only after wiring and components are proven good and the fault persists, or if a known faulty or outdated calibration is confirmed.

Can I keep driving?

Medium severity

The car can usually be driven for a short time to reach a garage, but a misfire and unburnt fuel can damage the catalytic converter, so have it checked soon. Avoid heavy loads and stop if the engine runs very roughly or the warning lamp flashes.

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

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