High Beam Relay Circuit
This code indicates a problem with the high beam relay circuit.
Heads up: this code wasn't in our hand-written library yet, so DiagCoach AI built this page on the fly. Double-check critical specs against service info before condemning parts.
What it means (plain English)
The high beam relay controls the high beam headlights. If there's an issue, either the relay is faulty, a wire is damaged, or the control signal isn't getting through.
What the computer is actually seeing
The computer monitors the status and expected operation of the high beam relay by checking for voltage signals. It expects to see around 12 volts at the relay when activated and 0 volts when deactivated.
What a healthy reading looks like
12 volts (+/- 1 volt) when high beams are on, 0 volts when they are off.
Guided diagnostic — the DiagCoach way
Don't just throw parts at it. Walk through these in order — each step tells you whether to keep going or stop and fix what you found.
- 11. Check the fuse related to the high beams. Replace if blown. Confirm if high beams work after replacement.
- 22. Inspect the high beam relay for proper operation. Swap with a known good relay. If high beams work, replace the relay.
- 33. Check voltage at the relay harness connector with the high beams activated. Expected: ~12V. If not present, check wiring and connections.
- 44. Test the high beam switch on the steering column for continuity. If no continuity when activated, replace the switch.
Common causes
- Faulty high beam relay
- Damaged wiring to the relay
- Failed switch on the steering column
- Poor ground connection
- Blown fuse for the headlights
Typical repair cost
$$ ($150 - $400)
Related codes
Frequently asked questions
Is it safe to drive with this code?
Yes, but you won't have high beam headlights, which can be a safety issue in low visibility conditions.
Will this code come back after clearing it?
It may return if the underlying issue isn't fixed, like a bad relay or wiring fault.
Why does this code pair with B2427?
B2427 also relates to the high beam circuit, usually indicating another issue with the same system.
Working a real vehicle right now?
Let DiagCoach walk you through it live with your specific symptoms, vehicle, and what you've already checked.
Start guided diagnostic →