Code
P1350
BUICK
P — Powertrain
Ignition Contol System
AI status
Completed
Completed
100%
Causes
- Faulty ignition coil(s) or ignition control module
- Open, shorted or corroded wiring/connectors in ignition control circuit
- Poor or missing power/ground to ignition module or coils
- Faulty crankshaft or camshaft position sensor (incorrect timing reference)
- Blown fuse or faulty ignition relay
- Intermittent PCM/ECM internal fault or damaged PCM connector
Symptoms
- Malfunction Indicator Lamp (MIL) illuminated
- Engine cranks but will not start or has hard starting
- Rough idle or pronounced misfire(s)
- Reduced engine power or stalling
- Poor fuel economy or intermittent drivability problems
What to check
- Retrieve and record freeze frame and all stored codes with a scan tool; note MIL status and freeze-frame conditions
- Perform visual inspection of ignition coils, module, connectors and wiring for damage, corrosion or loose pins
- Verify battery voltage (key ON and during cranking) and condition of charging system
- Check ignition fuses and ignition/PCM relays
- Confirm good PCM power and ground circuits
- Check for related crankshaft/camshaft position sensor codes and waveform presence
Signal parameters
- Key ON: ignition supply voltage ~ battery voltage (approx. 11.5–14.5 V depending on charging state)
- Cranking: coil primary voltage pulses present when cranking (backprobe primary lead to confirm switching)
- Coil primary resistance: typical low-ohm range (varies by coil type) — consult vehicle service data for exact values
- Coil secondary resistance: typically kilo-ohm range — consult vehicle service data for exact values
- Crankshaft/camshaft sensor: consistent reference pulse waveform at engine speed (use oscilloscope/scan tool)
Diagnostic algorithm
- Use a scan tool to read all DTCs and freeze frame data. Note any additional codes (misfire, cam/crank sensor).
- Inspect related connectors, wiring and harnesses for damage, corrosion, or loose pins at coils, ignition module and PCM.
- Verify battery voltage and charging system; charge or replace battery if low. Repeat test with good battery.
- Check fuses and relays powering the ignition coils/ignition module and PCM. Replace if faulty.
- Backprobe coil supply and control circuits with a DVOM or scope while cranking: confirm coil supply voltage, ground switching, and primary pulse pattern.
- Measure coil primary and secondary resistance and compare to factory specs. If out of range, replace coil.
- Check crankshaft/camshaft position sensor signals with an oscilloscope or scan tool; verify proper waveform and timing reference.
- If individual coil circuit codes are present, swap suspect coil with a known-good coil (when applicable) to see if the code or symptom follows the coil.
- If wiring and coils check good, test or replace the ignition control module/coil driver per OEM procedure.
- If all external components and wiring are good and the fault persists, consider PCM/ECM fault — verify PCM grounds/power and consult OEM diagnostics before replacement.
- Clear codes and perform a road/crank test to verify repair. Monitor for reappearance of P1350 or related codes.
Likely causes
- Loose or corroded connector at ignition coil/module
- Failed ignition coil or coil driver in ignition control module
- Damaged wiring harness (chafed wire to coil or module)
- Weak or low battery voltage during crank
- Faulty crankshaft position sensor causing loss of ignition timing signal
Fault status
Status
PCM detected an abnormal condition in the ignition control system (coil/ignition module/driver circuit or timing reference). MIL set and freeze-frame stored. Further electrical and component testing is required to isolate the root cause.
Repair difficulty: Medium
Diagnostic time: 1-3 hours
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