Left Tail Lamp Circuit Malfunction
What does B1005 mean?
The B1005 code means the vehicle's onboard diagnostic system has detected: Left Tail Lamp Circuit Malfunction. This is a moderate severity code.
Common Symptoms
- Left tail light not working
- Dashboard tail light warning indicator
- Left brake light may also be affected
- Rear left side not visible at night
- Intermittent tail light operation
Probable Causes (Ranked by Likelihood)
- Burned out left tail light bulb Very High
- Corroded tail light socket or ground High
- Damaged wiring to left tail light assembly Moderate
- Faulty tail light assembly with moisture intrusion Moderate
- BCM tail light output circuit failure Low
Step-by-Step Diagnostic Procedure
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Inspect left tail light bulb
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Check bulb socket for corrosion or melting
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Test ground connection at tail light assembly
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Check for voltage at tail light connector
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Inspect tail light housing for moisture or water damage
Frequently Asked Questions
Is a tail light the same as a brake light?
Some vehicles use a dual-filament bulb for both functions, while others use separate bulbs. A tail light stays on when headlights are on; brake lights illuminate when the brake pedal is pressed.
Can water in the tail light housing cause this?
Yes. Moisture intrusion into the tail light housing corrodes the socket and bulb contacts, leading to intermittent or complete failure of the circuit.
How do I check the tail light ground?
Locate the ground wire (usually black) at the tail light connector and test continuity from the ground wire to a clean metal point on the vehicle body using a multimeter.