What Does B2249 Mean?
This code indicates that the Body Control Module (BCM) has detected an abnormal voltage condition on the headlamp relay control circuit. Specifically, the relay coil circuit is seeing battery voltage when it should be at ground or floating, suggesting the control wire is shorted to a power source. This prevents the BCM from properly controlling the headlamp relay on/off operation.
Common Causes
45%
Damaged wiring harness causing the relay coil control wire to contact a power wire or fused circuit
30%
Failed headlamp relay with internal short circuit between coil and power terminals
15%
Corroded or damaged connector at relay or BCM allowing cross-circuit voltage feed
10%
Failed Body Control Module with internal driver circuit short to voltage
Diagnostic Steps
1
Step 1: Perform visual inspection of headlamp relay, relay socket, and associated wiring harness for signs of heat damage, melted insulation, corrosion, or pinched wires. Check for aftermarket accessories that may have tapped into headlamp circuits.
2
Step 2: Remove headlamp relay from socket and measure resistance across relay coil terminals using a multimeter (should read 50-120 ohms typically). Then measure voltage at the BCM control terminal in the relay socket with ignition on - should read 0-0.5V, not battery voltage.
3
Step 3: With relay removed and ignition off, disconnect BCM connector and measure resistance between the relay coil control wire and all power supply circuits in the harness. Infinite resistance (OL) is normal; any continuity indicates a short to power.
4
Step 4: If wiring tests normal, substitute a known-good relay and clear codes. If code returns immediately with new relay, suspect BCM internal fault. If code clears, repair or replace damaged wiring/connectors and verify headlamp operation through multiple on/off cycles.
5
Step 5: Perform functional test of headlamp system with all repairs completed, monitor live data for proper relay control signal from BCM, and road test to ensure code does not return.
Estimated Repair Cost
$75 - $650
Parts + labor, varies by vehicle and location
This code indicates that the Body Control Module (BCM) has detected an abnormal voltage condition on the headlamp relay control circuit. Specifically, the relay coil circuit is seeing battery voltage when it should be at ground or floating, suggesting the control wire is shorted to a power source. T...
The most common cause of B2249 (Head Lamp Relay Coil Short to Battery) is: Damaged wiring harness causing the relay coil control wire to contact a power wire or fused circuit
Typical repair costs for B2249 range from $75 to $650, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Vehicle may have inoperative headlamps or headlamps that remain on continuously, significantly compromising nighttime visibility and safety. Driving should be limited to daytime until repaired, and the fault poses a potential battery drain or electrical fire risk if relay remains energized.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to B2249 to identify the root cause.
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Quick Info
Category
Body
System
Exterior Lighting System
Difficulty
Type
Generic (SAE)
Recommended Tools
OBD2 Scanner
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