What does it mean?
P1352 is a Powertrain (engine, transmission, fuel system) fault code. It indicates: Ignition Control Bypass Circuit High Input .
Symptoms
- Engine starts but runs only on fixed base timing, feeling flat and lacking power
- Poor fuel economy and slow throttle response
- Hard starting, or occasional no-start conditions
- Detonation or run-on symptoms if the timing stays fixed at an unsuitable value
- Check engine light on with ignition control codes stored
Likely causes
- Bypass wire shorted to a voltage source in a damaged or wet harness section
- Open bypass circuit, which the module also interprets as a high level
- Corroded or loose connector at the ignition module
- Failed ignition control module unable to respond to the bypass signal
- Poor ground reference for the ignition module, distorting the measured level
- Previous repair with an incorrect splice or the bypass and control wires interchanged
- Failed bypass driver inside the powertrain control module
How to fix it
- Check for other ignition codes first, since bypass and control faults often appear together and share wiring
- Inspect the ignition module connector and both the bypass and control wires for corrosion, chafing and moisture
- With the key on, measure the bypass circuit voltage and compare it with the expected state for that condition
- Test the bypass wire for continuity to the control module and for a short to voltage
- Verify that the bypass and ignition control wires have not been swapped during earlier work
- Check ignition module ground integrity and clean the mounting surface
- Replace the ignition module if it does not respond correctly with proven-good wiring, then confirm timing advances normally