What Does B1299 Mean?
B1299 indicates the Body Control Module (BCM) has detected an abnormal short to ground condition in a power supply sensor circuit. This fault means a sensor reference voltage or signal wire is making unintended contact with vehicle ground, pulling the circuit voltage below acceptable thresholds. The BCM monitors various power supply sensors for airbags, occupant detection, or other body system components, and this code triggers when circuit resistance drops below specification due to grounding.
Common Causes
45%
Damaged or chafed wiring harness causing wire insulation breakdown and contact with chassis ground
30%
Corroded or moisture-contaminated connector terminals creating a ground path
15%
Faulty sensor internal short circuit causing signal wire to ground internally
10%
BCM internal circuit failure creating false short-to-ground detection
Diagnostic Steps
1
Step 1: Perform visual inspection of all body harness connectors and wiring near sensor locations, checking for obvious damage, corrosion, water intrusion, chafing against sharp edges, or pinched wires at body mounting points
2
Step 2: Using a digital multimeter, backprobe the sensor signal wire at the suspect sensor connector (disconnected) and measure resistance to ground - should read open circuit (OL or >10k ohms). If reading near 0 ohms, confirm short exists in harness or sensor
3
Step 3: Disconnect the BCM connector and repeat resistance measurement from sensor signal wire to ground - if short disappears (reads open), BCM has internal fault; if short persists, fault is in harness or sensor
4
Step 4: Isolate sensor from harness by disconnecting sensor connector and measure resistance of sensor signal pin to sensor ground/case - should be >10k ohms. If shorted, replace sensor
5
Step 5: If harness is confirmed faulty, perform wiggle test while monitoring resistance to locate intermittent short point, then inspect and repair damaged section with proper splice and heat shrink or replace harness segment
6
Step 6: After repair, clear codes, perform BCM relearn/initialization if required by manufacturer, and road test vehicle while monitoring live data to confirm circuit voltage returns to normal operating range (typically 5V or 12V reference)
Estimated Repair Cost
$100 - $650
Parts + labor, varies by vehicle and location
B1299 indicates the Body Control Module (BCM) has detected an abnormal short to ground condition in a power supply sensor circuit. This fault means a sensor reference voltage or signal wire is making unintended contact with vehicle ground, pulling the circuit voltage below acceptable thresholds. The...
The most common cause of B1299 (Power Supply Sensor Circuit Short To Ground) is: Damaged or chafed wiring harness causing wire insulation breakdown and contact with chassis ground
Typical repair costs for B1299 range from $100 to $650, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Vehicle is generally safe to drive, but depending on which power supply sensor is affected, airbag systems, seat occupancy detection, or other safety features may be disabled or malfunctioning. Repair should be completed promptly to ensure all safety systems function properly, especially if airbag warning light is illuminated.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to B1299 to identify the root cause.
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Quick Info
Category
Body
System
Body Control System
Difficulty
Type
Manufacturer
Recommended Tools
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