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P1355

IC Output High/Pulse Detected When Grounded Cyl.5.

  • Cadillac
  • Powertrain
  • Manufacturer code
  • Medium severity

How this code is built

P
SystemPowertrain
1
Defined byThe manufacturer
3
AreaIgnition system or misfire
55
FaultThe specific fault in that area

What it means

On a Cadillac, P1355 means the engine control module has seen a fault on the ignition control (IC) output for cylinder 5. The module expected the IC signal to go low when it grounded the circuit during the test, but it read high or detected a pulse. This points to a problem in the ignition control circuit, the ignition module or coil driver, or the wiring between them.

Symptoms

  • Engine misfire or rough running, especially at idle
  • Malfunction indicator lamp on
  • Hesitation or reduced power under load
  • Hard starting or extended cranking
  • Poor fuel economy
  • Smell of unburnt fuel from the exhaust

Possible causes

  • Damaged, chafed or shorted wiring in the cylinder 5 ignition control circuitlikely
  • Corroded or loose connector at the ignition module, coil or engine control modulelikely
  • Faulty ignition coil or ignition module driver for cylinder 5likely
  • Short to voltage on the IC circuit from another circuitpossible
  • Worn or fouled spark plug or damaged plug lead causing abnormal coil loadpossible
  • Faulty engine control module output driverrare

How to diagnose

  1. Read all stored and pending codes and note the freeze frame data (engine speed, load, temperature) to see when the fault set
  2. Check for other ignition or misfire codes, as they help show whether the fault is isolated to cylinder 5 or affects several cylinders
  3. Inspect the wiring and connectors for the ignition module, coil and engine control module for chafing, heat damage, water ingress and corrosion
  4. Inspect the cylinder 5 spark plug and lead or boot for wear, fouling, cracks or tracking
  5. Check the power, ground and reference feeds to the ignition module or coil against the wiring diagram for your model and engine
  6. Test the IC circuit for short to voltage and short to ground, and check resistance end to end with the connectors disconnected
  7. Swap the coil or module with a known good one from another cylinder, where the layout allows, and see if the fault follows
  8. Only if all of the above pass, check the engine control module output and consider module replacement

How to fix

  • Repair or replace damaged wiring in the cylinder 5 IC circuit
  • Clean, repair or replace faulty connectors and terminals
  • Replace the faulty ignition coil or ignition module
  • Replace worn or fouled spark plugs and any damaged leads or boots
  • Replace or reprogram the engine control module only once it is confirmed faulty, following the procedure for your model

Can I keep driving?

Medium severity

The car can usually be driven a short distance to get it repaired, but avoid heavy loads and long trips. A continuing misfire can overheat and damage the catalytic converter, so get it fixed soon.

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

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