B0034 moderate

Rear Left Turn Signal Circuit Malfunction

The B0034 code means the vehicle's onboard diagnostic system has detected: Rear Left Turn Signal Circuit Malfunction. This is a moderate severity code.

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Keep driving?
Short distances only
DIY difficulty
easy
Estimated cost
$5 - $200 (parts and labor)
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Common Symptoms

  • Rear left turn signal not flashing
  • Fast blink rate on dash indicator
  • Rear left signal stays solid
  • Turn signal warning on instrument cluster
  • Hazard lights only work on one side

Probable Causes (Ranked by Likelihood)

  • Burned out rear left turn signal bulb Very High
  • Corroded bulb socket in tail light assembly High
  • Broken wiring to rear left turn signal Moderate
  • Faulty turn signal relay or flasher module Low

Step-by-Step Diagnostic Procedure

  1. Visually inspect rear left turn signal bulb

  2. Check bulb socket for corrosion or melting

  3. Test voltage at bulb socket with multimeter

  4. Inspect wiring from body control module to rear light

  5. Test turn signal relay operation

Frequently Asked Questions

Why is my turn signal blinking fast?

A fast blink rate, called hyperflash, is the most common indicator that one of the turn signal bulbs has burned out. It is designed to alert the driver to a bulb failure.

Can I fix this myself?

In most cases yes. A burned out bulb is the most common cause and typically costs under $10 and takes minutes to replace by accessing the bulb through the trunk or tail light housing.

Is it legal to drive without a working turn signal?

No. Functioning turn signals are required by law in all states. Driving without a working turn signal can result in a traffic citation and is a safety hazard.

Sources

This page is built from documented references. Verify against your own service info before repair work.

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