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Engine-Codes – Pontiac – B3903 Pontiac

B3903 Pontiac Code - Stop Lamp Relay Circuit Short

Quick Answer

The B3903 Pontiac code indicates a problem with the stop lamp relay circuit in the vehicle. Common causes include Faulty stop lamp relay, Damaged wiring in the stop lamp circuit, Short circuit in the electrical system. 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
B3903 Pontiac indicates Stop Lamp Relay Circuit Short.
Common causes
Common causes include Faulty stop lamp relay, Damaged wiring in the stop lamp circuit, Short circuit in the electrical system.
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 11, 2024
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Code B3903 Pontiac Description

The B3903 Pontiac code indicates a problem with the stop lamp relay circuit in the vehicle. The stop lamp relay is responsible for controlling the power to the brake lights, which are crucial for the safety of the vehicle. When this circuit is shorted, it means that there is an unintended connection that is causing an abnormal flow of electricity. This can lead to the brake lights not functioning properly, which can pose a significant safety hazard on the road.

OBDII Code B3903 Pontiac - Stop Lamp Relay Circuit Short
B3903 Pontiac Code - Stop Lamp Relay Circuit Short

Common Causes of B3903 Pontiac

  1. Faulty stop lamp relay
  2. Damaged wiring in the stop lamp circuit
  3. Short circuit in the electrical system
  4. Corrosion in the connections related to the stop lamp relay
  5. Overloaded electrical system due to aftermarket modifications

Symptoms of B3903 Pontiac

  1. Brake lights not working
  2. Brake lights staying on continuously
  3. Fuse for brake lights blowing frequently
  4. ABS warning light or brake system warning light on the dashboard

How to Fix B3903 Pontiac

  1. Begin by diagnosing the specific cause of the short circuit in the stop lamp relay circuit using a multimeter to test for continuity and voltage.
  2. Inspect the wiring harness for any visible signs of damage or corrosion. Replace any damaged wiring as needed.
  3. Check the stop lamp relay for proper functioning. If faulty, replace the relay with a new one.
  4. Clear the diagnostic trouble codes and test the brake lights to ensure they are functioning correctly.
  5. Reassemble any components that were removed during the repair process and test drive the vehicle to confirm that the issue has been resolved.

Cost to Fix B3903 Pontiac

The typical repair costs for addressing a stop lamp relay circuit short can vary depending on the extent of the damage and the specific components that need to be replaced. On average, the parts for this repair can cost between $50 to $150, while the labor costs can range from $100 to $200. However, these costs can vary based on the location, vehicle make and model, and the rates of the auto repair shop. It's recommended to obtain a detailed estimate from a qualified mechanic before proceeding with the repair.

What does this mean?

Tech Notes for B3903 Pontiac

B3903 02 Stop Lamp Relay Circuit Short to Ground

B3903 05 Stop Lamp Relay Circuit Short to Battery or Open

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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 B3903 Pontiac Code

1. What are the common symptoms of OBDII code B3903 Pontiac (Stop Lamp Relay Circuit Short)?

- Common symptoms include non-functioning brake lights, illuminated brake warning light on the dashboard, and possible issues with cruise control.

2. What are the possible causes of OBDII code B3903 Pontiac?

- Possible causes include a short circuit in the stop lamp relay circuit, faulty stop lamp relay, damaged wiring or connectors, or a problem with the brake light switch.

3. How can I diagnose the OBDII code B3903 Pontiac?

- Diagnosis involves inspecting the stop lamp relay, checking the wiring and connectors for any damage or shorts, and testing the brake light switch for proper functionality.

4. What are some repair tips for resolving OBDII code B3903 Pontiac?

- Repair tips include repairing or replacing any damaged wiring or connectors, replacing the faulty stop lamp relay, and ensuring proper adjustment or replacement of the brake light switch.

5. Can OBDII code B3903 Pontiac cause any safety concerns?

- Yes, this code can pose safety concerns as non-functioning brake lights can reduce visibility to other drivers and increase the risk of rear-end collisions.

6. How urgent is it to address OBDII code B3903 Pontiac?

- It is recommended to address this code promptly to ensure the proper functioning of the brake lights and maintain safe driving conditions.

7. Can I still drive my Pontiac with OBDII code B3903?

- It is not advisable to drive the vehicle with non-functioning brake lights due to safety reasons. It is best to address the issue before driving the vehicle.

8. Will resetting the OBDII code B3903 Pontiac make the problem go away?

- Simply resetting the code will not resolve the underlying issue causing OBDII code B3903. The root cause of the problem will need to be diagnosed and repaired.

9. How much does it typically cost to repair OBDII code B3903 Pontiac at a repair shop?

- The cost of repairs can vary depending on the specific cause of the issue and the rates of the repair shop. It is best to get a diagnostic inspection to determine the exact cost.

10. Can I fix OBDII code B3903 Pontiac myself, or should I seek professional help?

- If you have experience with automotive repairs and diagnostics, you may be able to address the issue yourself. Otherwise, it is recommended to seek professional help to ensure proper repair and safety.

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