What Does B1356 Mean?
B1356 indicates the Body Control Module (BCM) has detected an open circuit in the ignition run circuit. This circuit supplies power to various vehicle systems when the ignition is in the RUN position. The BCM monitors this circuit and sets this code when it cannot detect proper voltage or continuity, indicating a break in the power distribution path from the ignition switch through the run circuit to monitored components.
Safety Warning
Vehicle may experience no-start condition, stalling while driving, or loss of power to critical systems including fuel pump, ignition coil, and engine control systems. Do not drive until diagnosed and repaired as sudden loss of ignition power can cause unexpected stalling in traffic.
Common Causes
35%
Faulty ignition switch or worn ignition switch contacts preventing proper circuit closure in RUN position
30%
Open or broken wiring between ignition switch and BCM, including corroded connectors or damaged harness
20%
Blown fuse or faulty fuse holder in the ignition run circuit power distribution
15%
Failed Body Control Module internal circuitry or poor BCM ground connection
Diagnostic Steps
1
Step 1: Perform visual inspection of ignition switch connector and BCM connector for corrosion, loose pins, or physical damage. Check all related fuses in the ignition run circuit using a test light or multimeter.
2
Step 2: With ignition key in RUN position (engine off), use a multimeter to verify battery voltage (12-14V) at the ignition switch output terminal for the run circuit. Compare to wiring diagram specifications.
3
Step 3: Backprobe the BCM connector at the ignition run circuit input pin with ignition in RUN position. Verify presence of battery voltage. If voltage is present at switch but not at BCM, trace wiring for opens or shorts.
4
Step 4: If voltage is present at BCM connector, check BCM ground circuits with multimeter for resistance less than 1 ohm to chassis ground. Verify ground integrity at all BCM ground points.
5
Step 5: If all wiring and grounds test good, perform ignition switch resistance test per manufacturer specifications by measuring resistance across switch terminals in various key positions. Replace switch if out of specification.
6
Step 6: After repairs, clear codes, cycle ignition key through all positions multiple times, and verify code does not return. Test all ignition run circuit dependent systems for proper operation.
Estimated Repair Cost
$100 - $650
Parts + labor, varies by vehicle and location
B1356 indicates the Body Control Module (BCM) has detected an open circuit in the ignition run circuit. This circuit supplies power to various vehicle systems when the ignition is in the RUN position. The BCM monitors this circuit and sets this code when it cannot detect proper voltage or continuity...
The most common cause of B1356 (Ignition Run Circuit Open) is: Faulty ignition switch or worn ignition switch contacts preventing proper circuit closure in RUN position
Typical repair costs for B1356 range from $100 to $650, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Vehicle may experience no-start condition, stalling while driving, or loss of power to critical systems including fuel pump, ignition coil, and engine control systems. Do not drive until diagnosed and repaired as sudden loss of ignition power can cause unexpected stalling in traffic.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to B1356 to identify the root cause.
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Quick Info
Category
Body
System
Body Control and Ignition System
Difficulty
Type
Manufacturer
Recommended Tools
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