What Does B1357 Mean?
This code indicates that the Body Control Module (BCM) has detected an unintended voltage source on the ignition run circuit, meaning battery voltage is present when it should not be. This occurs when the ignition run wire is shorted directly to a constant battery power source, bypassing the ignition switch control. The BCM monitors the ignition run circuit to ensure proper vehicle power distribution and has detected an abnormal electrical condition.
Safety Warning
This condition can cause excessive battery drain, unintended accessory operation with key off, and potential electrical fire risk from continuous current flow through circuits not designed for constant power. Vehicle should not be driven until repaired, and battery should be disconnected if vehicle must be left unattended.
Common Causes
45%
Damaged or chafed wiring harness causing ignition run wire to contact constant battery voltage wire
30%
Faulty ignition switch or switch assembly internally shorting run circuit to battery feed
15%
Damaged or incorrectly installed aftermarket accessories tapping into ignition circuit
10%
Corroded or damaged BCM connector causing internal cross-circuit shorting
Diagnostic Steps
1
Step 1: Perform visual inspection of ignition switch wiring harness from switch to BCM, looking for chafed insulation, melted wires, or signs of rubbing against metal surfaces or hot components
2
Step 2: Using a digital multimeter, backprobe the ignition run circuit at the BCM connector with ignition OFF and key removed - verify there is NO voltage present (should read 0V); if battery voltage is present, the short is confirmed upstream of BCM
3
Step 3: Disconnect the ignition switch connector and retest the ignition run circuit at BCM - if voltage disappears, ignition switch is faulty; if voltage remains, trace the wire between switch and BCM for damage or unauthorized splices
4
Step 4: Inspect all recent aftermarket installations (remote starters, alarms, audio equipment) for improper connections to ignition circuits, checking for inline taps or splice connectors
5
Step 5: If no external wiring faults found, remove and inspect BCM connector for terminal corrosion, pushed-back pins, or moisture intrusion that could cause internal cross-circuit contamination
6
Step 6: After repair, clear codes and verify ignition run circuit shows 0V with key off and proper switched voltage (typically 12V+) only when ignition is in RUN position
Estimated Repair Cost
$150 - $800
Parts + labor, varies by vehicle and location
This code indicates that the Body Control Module (BCM) has detected an unintended voltage source on the ignition run circuit, meaning battery voltage is present when it should not be. This occurs when the ignition run wire is shorted directly to a constant battery power source, bypassing the ignitio...
The most common cause of B1357 (Ignition Run Circuit Short To Battery) is: Damaged or chafed wiring harness causing ignition run wire to contact constant battery voltage wire
Typical repair costs for B1357 range from $150 to $800, depending on the vehicle, location, and whether you do it yourself or go to a shop.
This condition can cause excessive battery drain, unintended accessory operation with key off, and potential electrical fire risk from continuous current flow through circuits not designed for constant power. Vehicle should not be driven until repaired, and battery should be disconnected if vehicle must be left unattended.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to B1357 to identify the root cause.
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Quick Info
Category
Body
System
Body Electrical System / Ignition Control
Difficulty
Type
Manufacturer
Recommended Tools
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