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B3420 Chevrolet Code - Automatic Headlamp Leveling Control Module Rear Axle Sensor Signal

Quick Answer

The B3420 code for Chevrolet vehicles refers to an issue with the Automatic Headlamp Leveling Control Module Rear Axle Sensor Signal. Common causes include Faulty Automatic Headlamp Leveling Control Module Rear Axle Sensor, Electrical wiring issues, Sensor calibration error. Severity is High - diagnose this code as soon as possible. Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.

What it means
B3420 Chevrolet indicates Automatic Headlamp Leveling Control Module Rear Axle Sensor Signal.
Common causes
Common causes include Faulty Automatic Headlamp Leveling Control Module Rear Axle Sensor, Electrical wiring issues, Sensor calibration error.
Severity
High - diagnose this code as soon as possible.
Can I drive?
Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.
What is this?
Table of contents Created and updated by William Orellana on Sep 15, 2024
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Code B3420 Chevrolet Description

The B3420 code for Chevrolet vehicles refers to an issue with the Automatic Headlamp Leveling Control Module Rear Axle Sensor Signal. This code indicates that there is a problem with the sensor signal that is responsible for automatically adjusting the headlamp level based on the vehicle's load and angle. The headlamp leveling system is crucial for ensuring proper visibility at night and preventing glare for other drivers on the road.

OBDII Code B3420 Chevrolet - Automatic Headlamp Leveling Control Module Rear Axle Sensor Signal
B3420 Chevrolet Code - Automatic Headlamp Leveling Control Module Rear Axle Sensor Signal

Common Causes of B3420 Chevrolet

  1. Faulty Automatic Headlamp Leveling Control Module Rear Axle Sensor
  2. Electrical wiring issues
  3. Sensor calibration error
  4. Control module malfunction
  5. Physical damage to the sensor

Symptoms of B3420 Chevrolet

  1. Headlights pointing in the wrong direction
  2. Inconsistent headlamp leveling
  3. Dashboard warning light for headlamp system
  4. Headlights flickering or dimming

How to Fix B3420 Chevrolet

  1. Diagnose the issue by connecting a diagnostic scanner to retrieve the specific fault code and pinpoint the source of the problem.
  2. Inspect the Automatic Headlamp Leveling Control Module Rear Axle Sensor and wiring for any visible damage or loose connections.
  3. Test the sensor's functionality and calibration to determine if it is sending accurate signals to the headlamp leveling system.
  4. Replace the faulty sensor or control module if necessary, ensuring proper installation and calibration.
  5. Clear the fault code from the vehicle's system and test the headlamp leveling system to verify that the issue has been resolved.

Cost to Fix B3420 Chevrolet

The typical repair costs for addressing the B3420 code related to the Automatic Headlamp Leveling Control Module Rear Axle Sensor Signal can range from $200 to $500, including parts and labor. However, the specific diagnosis time and labor rates at auto repair shops can vary based on factors such as location, vehicle make and model, and engine type. It's recommended to check local rates for a more accurate estimate. Keep in mind that rates in metropolitan areas or at dealerships may be higher, while independent shops often charge less.

What does this mean?

Tech Notes for B3420 Chevrolet

B3420 02: Automatic Headlamp Leveling Control Module Rear Axle Sensor Signal Circuit Short to Ground

B3420 05: Automatic Headlamp Leveling Control Module Rear Axle Sensor Signal Circuit High Voltage/Open

B3420 08: Automatic Headlamp Leveling Control Module Rear Axle Sensor Signal Circuit Performance - Signal Invalid

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About the author: William Orellana is a Master Mechanic and Mechanical Engineer with over 30 years of experience diagnosing and repairing vehicles. Learn more about his background.

Frequently Asked Questions about B3420 Chevrolet Code

1. What does the OBDII code B3420 mean on a Chevrolet?

The B3420 code indicates an issue with the Automatic Headlamp Leveling Control Module, specifically a problem with the rear axle sensor signal.

2. What are the common symptoms of code B3420?

Symptoms may include malfunctioning or unresponsive automatic headlamp leveling, headlights aimed incorrectly, or a warning light on the dashboard.

3. What causes the B3420 code to appear?

Common causes include a faulty rear axle sensor, damaged wiring or connectors, corrosion in the circuit, or a malfunctioning headlamp leveling control module.

4. Can I drive with the B3420 code active?

Yes, but your headlights may not adjust properly, which could reduce visibility and safety during nighttime or uneven terrain driving.

5. How do I diagnose the cause of the B3420 code?

Start by inspecting the rear axle sensor, wiring, and connectors for damage or corrosion. Use a multimeter to test the sensor signal and check for continuity.

6. How do you fix the B3420 code on a Chevrolet?

Repairs may involve replacing the rear axle sensor, repairing or replacing damaged wiring, cleaning corroded connectors, or reprogramming or replacing the headlamp leveling control module.

7. How much does it cost to fix the B3420 code?

Repair costs can vary, but replacing the rear axle sensor typically costs $100-$300, including parts and labor. Additional costs may apply if the control module needs replacement.

8. Can a software issue cause the B3420 code?

Yes, in some cases, outdated or corrupted software in the headlamp leveling control module can trigger the code, requiring a software update or reprogramming.

9. What tools are needed to troubleshoot the B3420 code?

You’ll need a scan tool capable of reading body control module codes, a multimeter for testing electrical components, and possibly a service manual for wiring diagrams.

10. Will clearing the code with a scan tool fix the problem?

Clearing the code may temporarily remove the warning, but the underlying issue must be addressed to prevent the code from returning.

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