Code
P1352
MERCURY
P — Powertrain
Ignition Coil A Primary Circuit Fault
Views:
UK: 38
EN: 61
RU: 48
AI status
Completed
Completed
100%
Causes
- Failed/shorted/open ignition coil (coil A)
- Broken, corroded or disconnected wiring or connector in the coil primary circuit
- Poor or missing ground or battery feed to the coil
- Short to battery or short to ground in the coil primary conductor
- Faulty PCM ignition driver or internal PCM fault
- Moisture/contamination in coil connector or boot
Symptoms
- Malfunction Indicator Lamp (MIL) illuminated
- Engine rough idle or intermittent misfire
- Reduced engine power or hesitation on acceleration
- Decreased fuel economy
- Hard starting or stalling (in some cases)
- Misfire code(s) for the associated cylinder
What to check
- Retrieve freeze frame and live data with a scan tool; note misfire counts and related codes
- Visual inspection of coil A, connector and wiring for corrosion, damage, oil or moisture
- Verify battery voltage present at coil power feed with ignition ON
- Check for good ground at coil ground/engine block
- Measure coil primary resistance and compare to specification
- Perform continuity check from coil connector to PCM terminal
Signal parameters
- Primary coil resistance: typically very low (approx. 0.2–2.0 ohms) — refer to vehicle spec
- Secondary coil resistance: typically thousands of ohms (approx. 5–20 kΩ) — vehicle-specific
- Reference power: battery voltage (approx. 11–14.5 V) present at coil feed with ignition ON
- Control signal: PCM provides a switching (pulsed) driver to the coil primary; pulse width and frequency vary with RPM and engine load
- Expected primary waveform: sharp switching edges with consistent current pulses; no continuous short to ground or battery
Diagnostic algorithm
- Read and record all stored codes, freeze frame and live data. Note which cylinder is affected and any misfire counts.
- Perform a visual inspection of coil A, connector and wiring for damage, oil or corrosion. Repair visible faults.
- With ignition OFF, disconnect coil connector and inspect pins for corrosion/bent pins. Repair or replace connector as needed.
- With ignition ON (engine off), verify battery voltage at the coil power supply terminal. Replace fuse/relay if feed missing.
- Check ground continuity from coil ground to chassis/engine ground.
- Measure coil primary resistance at coil terminals (or between coil power and driver pin) and compare to specification. If out of range, replace coil.
- Perform continuity/resistance check between coil driver pin and PCM terminal. Repair any open or shorted wiring.
- If wiring and power/ground are good, swap coil A with another cylinder's coil and clear codes. If fault moves to other cylinder, replace the coil.
- If problem is intermittent or not reproduced, use an oscilloscope to capture primary waveform while cranking/running to identify driver anomalies, excessive current draw or short conditions.
- If wiring, connector and coil test good but fault persists, investigate/replace PCM or perform PCM module tests per manufacturer procedures (seek service manual guidance).
- After repair, clear codes and road-test to confirm repair; re-scan to ensure no return of P1352 or related codes.
Likely causes
- Defective ignition coil A (internal open or short in primary winding)
- Loose, corroded or pushed-out coil connector
- Damaged insulation or broken wire between coil and PCM/power/ground
- Blown fuse or fusible link feeding the coil primary
- Intermittent connection due to vibration or heat (wiggle-susceptible harness)
Fault status
Status
PCM detected a fault in ignition coil A primary circuit (open/short/driver error). May cause misfire and illuminate the MIL. Inspect coil, wiring, connectors, power/ground and PCM driver.
Repair difficulty: Medium
Diagnostic time: 0.5-3.0 hours
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