Flash To Pass Switch Circuit Failure
The flash-to-pass switch (high-beam lever) circuit isn't communicating properly with the vehicle's body control module. Think of it like a light switch that's either broken, unplugged, or has a loose wire.
The body control module monitors the voltage signal from the flash-to-pass switch circuit when the driver pulls the high-beam lever. It expects a clean digital signal (open/closed) or analog voltage within a specific range. If the signal is missing, shorted, or out of range for too long, the ECU logs this fault.
| Parameter | Normal Range | Fault Condition |
|---|---|---|
| Switch Signal Voltage | 0V (open) or 12V (closed) | No signal, floating voltage, or stuck state |
| Circuit Resistance | <1 Ohm closed, >10 kΩ open | Out-of-range resistance or open circuit |
Code B1507 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, B1507 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.