B1352
Ignition Key-In Circuit Failure
Body Chassis/Safety Ignition Detection 🟢 Low — Fix at next service
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What This Actually Means
In plain language — no jargon

The vehicle's ignition key detection circuit isn't working properly, like a light switch that can't tell if it's turned on or off. The ECU can't reliably sense whether the key is in the ignition position.

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Symptoms You May Notice
3 known symptoms for this code
Dashboard lights flicker or behave erratically when key is inserted
Vehicle won't start or has intermittent starting issues
Electrical accessories don't respond consistently to key position changes
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Embedded Systems Insight
What the ECU/ECM is actually computing

The ECU monitors the ignition key-in circuit voltage signal, which should change states when the key is inserted, turned, or removed. The circuit typically uses a dedicated switch or sensor that provides a discrete signal to indicate key presence and position. When voltage levels don't match expected thresholds or transitions occur unexpectedly, the fault is triggered.

Voltage & Parameter Thresholds

Parameter Normal Range Fault Condition
Key-In Signal Voltage 5V or 12V depending on state Voltage stuck low, high, or erratic transitions
Signal Detection Frequency Stable state changes per key action No state change or continuous flickering
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Diagnostic & DIY Fix Guide
Check these in order — from cheapest to most complex
1
Ignition Switch Contacts/Connectors
Clean and reseat all connectors at the steering column ignition switch to remove corrosion and ensure solid contact.
2
Ignition Switch Assembly
Replace the ignition switch if cleaning doesn't resolve the issue, as internal contacts may be worn or failed.
3
Body Control Module Wiring Harness
Inspect wiring harness from ignition switch to BCM for cuts, pinches, or loose terminals and repair as needed.