Lamp Turn Signal Left Circuit Failure
The left turn signal lamp circuit isn't working properly, similar to a light switch that won't turn on because the wire is broken or disconnected. The vehicle's computer detected an electrical fault in the left turn signal lamp circuit.
The ECU monitors the left turn signal lamp circuit by measuring current draw through the bulb when the turn signal is activated. It detects opens, shorts, or excessive resistance by comparing actual current against expected values. If current is absent or abnormally low/high, a fault is triggered.
| Parameter | Normal Range | Fault Condition |
|---|---|---|
| Lamp Current Draw | 0.3–0.8 A (typical bulb) | Below 0.1 A or open circuit detected |
| Circuit Voltage | 12–14 V when activated | 0 V or voltage drop indicates break/poor connection |
Code B1499 is a low-severity fault. Your vehicle is generally safe to drive to a workshop for diagnosis. However, do not ignore it indefinitely — low-severity codes often indicate developing problems that become expensive if neglected. Book a diagnostic appointment within 2–4 weeks. If you notice any additional symptoms (rough running, power loss, unusual smells), treat it as higher priority.
Once the fault is repaired, B1499 can be cleared using any OBD-II scanner. Connect the scanner, navigate to "Clear Codes" or "Erase DTCs," and confirm. The check engine light turns off immediately.
The code will return if the root cause was not actually fixed. The ECM re-detects the fault within 1–3 drive cycles and sets the code again.