What does it mean?
B1510 is a Body (airbags, seat belts, body electronics) fault code. It indicates: Flash To Pass Switch Circuit Short to Ground .
Symptoms
- High beams flash on their own or stay on
- Flash to pass does not work at all, or works without touching the stalk
- Headlamp behaviour becomes erratic, particularly when the stalk is moved
- Battery drain overnight if the lamps stay energised
- Oncoming drivers flashing back because the high beams are on unnoticed
Likely causes
- Worn or contaminated contacts inside the multifunction switch, sticking the flash circuit closed
- Water running down the steering column from a windscreen or cowl leak into the switch
- Signal wire chafed against the column bracket or the tilt mechanism
- Terminal pushed out of the column connector and touching the metal column
- Damaged wiring after steering column, wheel or airbag work
- Body control module input stage failure holding the circuit low
- Aftermarket lighting or alarm wiring tapped into the headlamp flash circuit
How to fix it
- Confirm the symptom first: watch the flash to pass switch status in live data with the stalk released
- Unplug the multifunction switch connector; if the code and the symptom clear, the switch is the fault
- With the switch unplugged, measure the signal wire to ground; a low resistance proves a short in the harness
- Inspect the harness at the column tilt joint and the connector for chafing and pushed-back terminals
- Check for water tracking down the column and dry, clean and reseal the entry point
- Replace the multifunction switch if its contacts are worn, burnt or contaminated
- Repair the shorted harness section, and only then consider the body control module input circuit