What Does B1397 Mean?
This code indicates the Body Control Module (BCM) has detected an unintended voltage (battery power) on the power door unlock circuit when it should be off or grounded. This means the unlock circuit is shorted directly to battery voltage, causing the BCM to register a fault in the door lock control system. The BCM monitors this circuit for proper operation and sets this code when it detects continuous battery voltage present on the unlock command wire.
Common Causes
45%
Damaged or chafed wiring harness causing short to power between BCM and door lock actuators
30%
Failed door lock actuator with internal short to power
15%
Faulty door lock relay stuck closed or internally shorted
10%
Water intrusion or corrosion in door lock switch or BCM connector causing cross-circuit short
Diagnostic Steps
1
Step 1: Visually inspect all door lock wiring harnesses, particularly at door jamb flex points and behind door panels, looking for chafed, pinched, or damaged insulation that could cause shorts to power wires
2
Step 2: Disconnect the door lock actuator connectors one at a time at each door and clear codes after each disconnection to isolate which actuator circuit is causing the short (code should clear when faulty circuit is disconnected)
3
Step 3: Using a digital multimeter, backprobe the unlock circuit wire at the BCM connector with all actuators disconnected and measure voltage to ground with ignition on (should read 0V; battery voltage confirms wiring harness short)
4
Step 4: If wiring tests good, check door lock relay operation by removing relay and testing for continuity across terminals; if relay is stuck closed or shows incorrect resistance values, replace relay
5
Step 5: Inspect BCM connectors for water intrusion, corrosion, or bent pins causing cross-circuit shorts; clean and repair connectors as needed
6
Step 6: After repair, reconnect all components, clear codes, and cycle door locks multiple times using key fob and interior switches to verify proper operation and confirm code does not return
Estimated Repair Cost
$100 - $600
Parts + labor, varies by vehicle and location
This code indicates the Body Control Module (BCM) has detected an unintended voltage (battery power) on the power door unlock circuit when it should be off or grounded. This means the unlock circuit is shorted directly to battery voltage, causing the BCM to register a fault in the door lock control ...
The most common cause of B1397 (Power Door Unlock Circuit Short To Battery) is: Damaged or chafed wiring harness causing short to power between BCM and door lock actuators
Typical repair costs for B1397 range from $100 to $600, depending on the vehicle, location, and whether you do it yourself or go to a shop.
This code does not affect vehicle safety or drivability and the vehicle is safe to drive. The primary concern is potential door lock malfunction where doors may not lock/unlock properly or drain battery if relay remains energized, so repair should be completed within a reasonable timeframe.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to B1397 to identify the root cause.
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Quick Info
Category
Body
System
Body Control and Door Lock System
Difficulty
Type
Manufacturer
Recommended Tools
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