Code
B2519
Other
B — Body
High Mount Stop Lamp Circuit Failure
AI status
Completed
Completed
100%
Causes
- Burned out or failed CHMSL bulb or LED module
- Open or shorted wiring between lamp and body control module (BCM)
- Corroded, loose or damaged lamp connector or ground
- Blown fuse or fusible link for stop lamp circuit
- Faulty body control module or switch (brake light switch)
- Water intrusion or physical damage at the lamp housing
Symptoms
- Center high‑mount stop lamp inoperative or intermittent
- Brake lights may not illuminate or may flicker
- Possible illumination of a body/chassis warning or stored B‑code
- Reduced visibility to following traffic (safety concern)
What to check
- Scan for B2519 and read freeze frame / occurrence count
- Visually inspect CHMSL lens, connector and wiring for damage or corrosion
- Check fuse(s) for stop/taillight circuits
- Operate brake pedal while observing CHMSL and related lamps
- Backprobe the CHMSL connector to measure voltage with brake applied
- Check connector pins for corrosion, bent pins or poor contact
Signal parameters
- CHMSL feed voltage with brake pedal depressed: approx. 11–14.5 V (depending on battery/charging)
- CHMSL feed voltage with pedal released: ~0 V (or high impedance/open depending on design)
- Typical incandescent lamp current: ~0.5–3 A (per lamp) — LED modules lower (often
- Expected continuity between lamp terminal and BCM output when connected: low resistance (ohms range)
- Expected ground resistance:
Diagnostic algorithm
- Connect a scan tool, confirm DTC B2519 and note freeze frame / occurrence pattern; clear codes and see if it returns.
- Inspect the CHMSL assembly and wiring visually for corrosion, water, damage or pin deformation; repair as needed.
- Check related fuses and replace if blown. Verify fuse circuit power supply is present.
- With a helper depressing the brake pedal, backprobe the CHMSL power terminal and measure voltage. Record readings.
- If correct voltage is present at connector but lamp does not light, remove lamp/LED module and bench‑test or substitute known good lamp.
- If no voltage at lamp connector with pedal depressed, trace back toward the BCM: check continuity between lamp positive terminal and BCM output pin, checking for opens or high resistance.
- Inspect and measure ground continuity from lamp ground to chassis/battery negative; repair poor ground connections.
- If intermittent, wiggle harness and connectors while monitoring voltage or scan data to reproduce the fault; repair or replace damaged wiring/connector.
- If wiring and lamp are good but no correct drive signal from BCM, verify brake light switch operation and inputs to BCM. Consult wiring diagram for signal path.
- If BCM driver output is confirmed faulty after wiring and switch checks, follow manufacturer procedure for BCM diagnostics and replacement. Verify recheck and clear codes after repair.
Likely causes
- Failed lamp (burned filament or LED failure)
- Poor ground or corroded connector at CHMSL
- Open circuit in wiring (broken wire, chafing)
- Short to ground or short to voltage on CHMSL feed
- Intermittent connector contact due to moisture or vibration
Fault status
Status
High Mount Stop Lamp (CHMSL) circuit fault detected — open/short/intermittent or incorrect load on lamp circuit.
Repair difficulty: Medium
Diagnostic time: 0.5-2.0 hours
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