Lamp Headlamp Input Circuit Open
The headlamp input signal wire is broken or disconnected, so the body control module can't detect whether the headlamps are on or off. Think of it like a light switch with a severed wire—the switch works, but nothing receives the signal.
The body control module (BCM) monitors the headlamp input circuit for a valid voltage signal (typically 12V when headlamps are on, 0V when off). When the circuit is open, the module detects an abnormal high-impedance state and cannot distinguish headlamp status. The BCM uses this signal for automatic light control, daytime running lights, and light-off reminder functions.
| Parameter | Normal Range | Fault Condition |
|---|---|---|
| Headlamp Input Voltage | 0V (off) or 12V (on) | Open circuit (>15 kΩ resistance) |
| Signal Detection Time | <500ms response | No voltage change detected |
Code B1471 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, B1471 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.