P1359

Code

CADILLAC P — Powertrain

Ignition Control Circuit Group A

Brand: CADILLAC

Type: P — Powertrain

Views: UK: 23 EN: 50 RU: 24

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Page language: EN

Causes

Open, shorted, or intermittent wiring/connectors in the ignition coil driver circuit
Faulty ignition coil(s) in group A (coil-on-plug or coil pack)
Faulty ECM/PCM ignition driver(s)
Low or erratic battery/primary power or poor ground
Corrosion, water intrusion, or physical damage at coil or ECM connectors
Related sensor faults or multiple misfire conditions that affect driver operation

Symptoms

Check Engine light (MIL) illuminated
Engine misfire or rough idle, especially at low RPM
Hard start or no-start condition in some cases
Reduced engine power or hesitation under load
Possible increased fuel consumption and emissions

What to check

Read freeze-frame data and stored DTCs with a scan tool; note misfire counts and related codes
Visual inspection of coil boots, connectors, and wiring harness near valve cover for damage or contamination
Verify battery voltage and charging system (should be ~12.4–14.6 V with engine running)
Check for poor ground points and clean/tighten as required
Backprobe coil connector while cranking/running to observe command and coil supply
Swap coils within same cylinder bank (group A) to see if code/misfire follows the coil

Signal parameters

Ignition coil primary supply voltage: approx. battery voltage (12–14.5 V) at coil + terminal
Coil primary resistance (typical COP): ~0.5–2.0 Ω (manufacturer-specific — consult service data)
Coil secondary resistance: typically thousands of ohms (5 kΩ–30 kΩ range depending on design)
Command signal type: ECM usually switches coil primary to ground; expect a pulsed ground command during cranking/running
Command pulse frequency: varies with engine speed; duty cycle/pulse width varies by load and RPM
Driver current: ignition coil primary current typically in the amp range during dwell (manufacturer-specific)

Diagnostic algorithm

Retrieve all DTCs and live data. Note freeze-frame, misfire counts, and whether the fault is intermittent or permanent.
Perform a visual inspection of coil group A wiring and connectors. Look for corrosion, oil/water intrusion, pin damage, or insulation chafing.
Verify battery/charging system voltage. Low supply voltage can cause driver faults; repair charging/battery issues first.
With ignition ON or engine cranking, backprobe the coil connector: confirm proper battery feed at the + terminal and a switching command (to ground) from ECM at the driver terminal.
Measure coil primary resistance and compare to service data. Replace any coil outside specification or with visible damage.
Swap a suspect coil with a known-good coil from another cylinder in the same bank. If the DTC/misfire follows the coil, replace the coil.
If coil and harness appear OK, check continuity and resistance of the control circuit between the coil connector and the ECM pin. Inspect for short to ground or battery voltage.
Inspect the ECM connector for corrosion, bent pins, or evidence of overheating. If harness and coils test good but driver pin is abnormal (short to ground/voltage or open), suspect ECM failure.
Before replacing ECM, confirm all wiring, coils, grounds, and power supplies are good. Consider professional bench testing or module programming if ECM replacement is required.
Clear codes and perform a road/test-cycle to verify repair. Re-scan for any returning faults.

Likely causes

Damaged or loose connector at ignition coil(s) (corrosion, bent pins, oil/water contamination)
Short to voltage or ground in the coil primary wiring harness (chafed insulation)
One or more failed ignition coils in the affected group
Failed driver transistor inside the ECM due to overload/heat/damage
Low battery voltage or weak charging system causing driver anomalies

Fault status

⚠️ Status

Ignition Control Circuit Group A fault detected — check ignition coils, wiring/connectors, power/ground, and ECM driver for faults.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 1.0 - 2.5 hours

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P1359 — Ignition Control Circuit Group A