Code
B2549
HYUNDAI
B — Body
Left Headlamp(High Beam) Open
Views:
UK: 17
EN: 24
RU: 14
AI status
Completed
Completed
100%
Causes
- Burned-out (open) high-beam bulb/LED module
- Blown fuse or faulty relay for headlamps
- Open or broken wiring between BCM (or headlamp driver) and left high-beam lamp
- Corroded or loose connector or socket at the lamp
- Failed headlamp driver module or BCM output stage
- Poor or open ground connection
Symptoms
- Left high-beam lamp does not illuminate while right high-beam works
- Driver/BCM may show lamp-out warning or a dashboard warning indicator
- Headlamp fault message displayed (depending on vehicle features)
- Intermittent operation or only when harness is moved (indicates wiring/connector issue)
What to check
- Verify customer complaint and check whether right high-beam functions normally
- Visually inspect left headlamp assembly, socket, and connector for damage, corrosion, moisture
- Check relevant fuses and relays for the headlamp/high-beam circuit
- Use a scan tool to read BCM/body module lamp status and any related codes
- Measure voltage at the lamp connector with high beams ON and OFF
- Check continuity between lamp connector and BCM/driver output and to chassis ground
Signal parameters
- Voltage at left high-beam connector with high beams ON: approx. battery voltage (≈11–14 V)
- Voltage at connector OFF: near 0 V (or open depending on circuit design)
- Lamp filament resistance (halogen, cold): typically ~0.5–5 ohms; open = OL/infinite
- Ground resistance: ideally
- For LED modules: expected current draw and driver voltage vary—refer to vehicle service data; an open is indicated by 0 A or open circuit reading
Diagnostic algorithm
- Confirm the fault: Turn on high beams and verify the left lamp is not illuminated; note any dash warnings.
- Scan vehicle: Read BCM/body module for B2549 and any related codes; record freeze frame if available.
- Visual inspection: Check bulb/module, socket, wiring, connector seals, and fuses/relays for obvious damage or corrosion.
- Bulb check: Remove the lamp and inspect filament or LED module. If halogen bulb suspect, test with an ohmmeter or substitute a known good bulb.
- Fuse/relay: Verify fuse continuity and relay operation for the headlamp circuit; replace if faulty.
- Voltage test at connector: With high beams ON, measure voltage at the positive pin of the left headlamp connector. If battery voltage present, suspect lamp or ground. If no voltage, trace back toward BCM/relay.
- Ground/continuity: Measure continuity between lamp ground and chassis ground. Repair any high-resistance or open ground.
- Wiring harness test: Check continuity from lamp connector to BCM/driver output. Repair any open circuits, damaged wires, or corroded terminals.
- Module output: If wiring and lamp are good but no drive signal from BCM/driver, test the BCM output per service manual. Replace or reprogram BCM/driver only after confirming wiring and lamp integrity.
- Reassemble and verify: Clear codes, reassemble, and re-check operation. Road test and re-scan to confirm repair.
Likely causes
- Open filament or failed LED module in the left high-beam lamp
- Open wiring/connector between lamp and BCM (rodent damage, chafing, broken pin)
- Blown fuse or failed relay protecting the high-beam circuit
- Faulty ground or high resistance at lamp ground
- Failed headlamp driver / BCM output (less common than wiring or bulb)
Fault status
Status
Left headlamp (high beam) open circuit detected. Left high-beam lamp is not functioning. Inspect lamp, fuse/relay, wiring, connectors and BCM/headlamp driver.
Repair difficulty: Medium
Diagnostic time: 0.5 - 2.0 hours
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