B1357
Ignition Run Circuit Short To Battery
Body Chassis/Safety Electrical Control Circuit 🟢 Low — Fix at next service
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What This Actually Means
In plain language — no jargon

The ignition run circuit is detecting excessive voltage, as if it's being shorted directly to the battery instead of being properly controlled. Think of it like a water line that's supposed to have controlled flow but instead has a direct pipe to the main supply, causing pressure to spike.

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Symptoms You May Notice
3 known symptoms for this code
Illuminated check engine light or body control module warning
Vehicle may not start or has erratic starting behavior
Electrical systems or accessories behaving unexpectedly
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Embedded Systems Insight
What the ECU/ECM is actually computing

The body control module monitors the ignition run circuit voltage through a dedicated input pin. It expects to see a controlled voltage signal that transitions properly during ignition key cycles. When the module detects voltage at or near battery potential (12-14V) when it should be lower or switching, it logs a short-to-battery fault.

Voltage & Parameter Thresholds

Parameter Normal Range Fault Condition
Ignition Run Circuit Voltage 0-5V controlled signal or switched ground 9.5V+ sustained when circuit should be inactive
Circuit Resistance Proper relay/switch operation with <1 ohm closed Direct short path to battery (+12V rail)
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Diagnostic & DIY Fix Guide
Check these in order — from cheapest to most complex
1
Ignition switch or steering column connectors
Inspect for corrosion, bent pins, or damaged connectors in the ignition switch harness and reseat connections.
2
Ignition run relay
Test or replace the relay that controls the ignition run circuit for internal shorts.
3
Body control module or wiring harness
Check for pinched, melted, or damaged wiring between the BCM and ignition switch; repair or replace as needed.