Rear Lamp Fault
Indicates a malfunction in the rear lamp assembly.
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 vehicle’s computer is detecting that there's a problem with one of the rear lights not working correctly, whether it's a bulb, wiring, or connector issue.
What the computer is actually seeing
The BCM (Body Control Module) monitors the rear lamps for functional voltage; if it detects a voltage difference indicating an open circuit (0 volts or very low) or a short to ground, it sets this code.
What a healthy reading looks like
Should see around 12 to 14 volts at the rear lamp circuit when the lights are activated; 0 volts when they're 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. Inspect the rear lamp assemblies for any visibly burnt out bulbs; replace as needed. Decision: If bulbs are good, proceed to step 2.
- 22. Check the wiring and connectors for corrosion, broken wires, or loose connections. Use a multimeter to test for continuity; repair any issues found. Decision: If no wiring issues, continue to step 3.
- 33. Measure the voltage at the rear lamp connector while activating the lights; expect 12-14 volts. Decision: If voltage is present and the lights still don’t work, consider replacing the rear lamp assembly or BCM.
Common causes
- Burnt out bulb
- Corroded connectors
- Damaged wiring harness
- Faulty BCM
Typical repair cost
$$
Related codes
Frequently asked questions
Is it safe to drive with this code?
Yes, but you should fix it soon to avoid being a hazard to others if your rear lights fail completely.
Will the code come back after I fix it?
If fixed properly, the code should clear and not return unless there’s a recurring issue.
Why is this code sometimes paired with B2601?
B2601 is often triggered in conjunction as both relate to the rear lighting circuitry and different aspects of malfunction.
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