What Does B2519 Mean?
This code indicates the Body Control Module (BCM) has detected an electrical fault in the center high-mounted stop lamp (CHMSL or third brake light) circuit. The BCM monitors this circuit for proper operation and sets this code when it detects an open circuit, short to ground, short to power, or excessive resistance. This safety-critical brake lighting circuit failure means the third brake light is not functioning when the brake pedal is applied.
Common Causes
45%
Failed or burned out CHMSL bulb or LED assembly
30%
Damaged wiring or corroded connections in CHMSL circuit between BCM and lamp
15%
Faulty CHMSL socket with corrosion or poor contact
10%
BCM internal driver circuit failure or faulty brake light switch signal
Diagnostic Steps
1
Step 1: Visually inspect the center high-mounted stop lamp for obvious bulb failure, physical damage, or water intrusion. Have an assistant apply the brake pedal while observing if the CHMSL illuminates at all or shows intermittent operation.
2
Step 2: Remove the CHMSL assembly and inspect the bulb/LED unit and socket for signs of corrosion, overheating, or damaged contacts. Test bulb continuity with a multimeter (should read 2-5 ohms for incandescent, verify LED function with power supply).
3
Step 3: Using a multimeter, backprobe the CHMSL connector at the lamp with brake pedal applied. Verify presence of battery voltage (12-14V) on the power supply wire. If no voltage present, trace circuit back toward BCM checking for open circuits or damaged wiring.
4
Step 4: Check ground circuit continuity from CHMSL ground wire to chassis ground (should be less than 0.5 ohms resistance). Clean and repair any corroded ground connections found.
5
Step 5: If power and ground are present but lamp doesn't function, replace the CHMSL assembly. If no power reaches the lamp with brake applied, check BCM output circuit with wiring diagram and verify brake light switch signal to BCM is functioning properly.
6
Step 6: After repairs, clear the code, cycle the brake pedal multiple times, and verify CHMSL operates correctly. Road test and confirm code does not return.
Estimated Repair Cost
$75 - $350
Parts + labor, varies by vehicle and location
This code indicates the Body Control Module (BCM) has detected an electrical fault in the center high-mounted stop lamp (CHMSL or third brake light) circuit. The BCM monitors this circuit for proper operation and sets this code when it detects an open circuit, short to ground, short to power, or exc...
The most common cause of B2519 (High Mount Stop Lamp Circuit Failure) is: Failed or burned out CHMSL bulb or LED assembly
Typical repair costs for B2519 range from $75 to $350, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Vehicle is drivable but the third brake light provides critical warning to following drivers, especially in stop-and-go traffic. Repair should be completed promptly as this is a safety violation in most jurisdictions and increases rear-end collision risk.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to B2519 to identify the root cause.
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Quick Info
Category
Body
System
Body Lighting System
Difficulty
Type
Generic (SAE)
Recommended Tools
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