What Does B2494 Mean?
This diagnostic trouble code indicates that the Body Control Module (BCM) has detected a short to battery voltage in the anti-theft system's horn output circuit. The horn circuit is receiving constant battery voltage when it should not be energized, meaning the horn wire is making unintended contact with a power source. This prevents proper anti-theft system operation and may cause the horn to sound continuously or activate unexpectedly.
Common Causes
45%
Damaged or chafed wiring harness where horn circuit contacts battery voltage
30%
Failed horn relay stuck in closed position or internally shorted
15%
Shorted horn switch or clock spring assembly
10%
Failed BCM with internal short in horn driver circuit
Diagnostic Steps
1
Step 1: Disconnect the horn relay and observe if the DTC clears and horn stops sounding. Use a multimeter to check for battery voltage at the horn output circuit terminal with relay removed - if voltage is present, the short is between BCM and relay socket.
2
Step 2: With horn relay still removed, check for continuity between the BCM horn output wire and battery voltage using a multimeter. Wiggle wiring harnesses near sharp metal edges, frame rails, and through firewall grommets while monitoring for intermittent shorts.
3
Step 3: Inspect horn relay for internal short by testing relay resistance across coil and contact terminals. Replace relay if internal resistance shows short circuit or test a known good relay in the socket.
4
Step 4: If short persists with relay removed, disconnect BCM connector and test horn output wire for short to battery voltage. If short disappears, BCM has internal fault. If short remains, trace and repair wiring harness between BCM and horn relay.
5
Step 5: After repairs, reconnect all components, clear codes, and command horn activation using scan tool active test function to verify proper operation and confirm no voltage present when horn should be off.
Estimated Repair Cost
$100 - $650
Parts + labor, varies by vehicle and location
This diagnostic trouble code indicates that the Body Control Module (BCM) has detected a short to battery voltage in the anti-theft system's horn output circuit. The horn circuit is receiving constant battery voltage when it should not be energized, meaning the horn wire is making unintended contact...
The most common cause of B2494 (ANTI THEFT HORN OUTPUT CIRCUIT Short to Batt) is: Damaged or chafed wiring harness where horn circuit contacts battery voltage
Typical repair costs for B2494 range from $100 to $650, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Vehicle is safe to drive but anti-theft system may not function properly and horn may sound unexpectedly or continuously, causing driver distraction and battery drain. Repair within a few days to restore security system function and prevent battery discharge.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to B2494 to identify the root cause.
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Quick Info
Category
Body
System
Anti-Theft Security System
Difficulty
Type
Generic (SAE)
Recommended Tools
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