AutoCodes – Pontiac – B3903 Pontiac

B3903 Pontiac Code - Stop Lamp Relay Circuit Short

Quick Answer

The Body Control Module (BCM) supplies voltage to the Center High Mount Stop Lamp (CHMSL) and the Powertrain Control Module (PCM) when the stop lamps are active. Common causes include Faulty Stop Lamp Relay, Stop Lamp Relay harness is open or shorted, Stop Lamp Relay circuit poor electrical connection. 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, Stop Lamp Relay harness is open or shorted, Stop Lamp Relay circuit poor electrical connection.
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.

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Code Popularity 600

How popular is this code, among other codes? Low

Repair Importance Level

Urgent (Diagnose now) (3 / 3)

Repair Difficulty Level

Advanced (Pro) (3 / 3)

What is this?

Table of contents Created and updated by William Orellana on Mar 25, 2020

Description
Possible Causes
How To Fix
Tech Notes
Cost to Diagnose
FAQs
Comments
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Code B3903 Pontiac Description

The Body Control Module (BCM) supplies voltage to the Center High Mount Stop Lamp (CHMSL) and the Powertrain Control Module (PCM) when the stop lamps are active. The Diagnostic Trouble Code (DTC) sets when if the stop lamp switch signal circuit is shorted to ground for 125 ms or if is open or shorted to voltage for 125 ms.

OBDII Code B3903 Pontiac - Stop Lamp Relay Circuit Short - AutoCodes.com — B3903 Pontiac Code - Stop Lamp Relay Circuit Short

What does this mean?

What are the Possible Causes of the DTC B3903 Pontiac?

Faulty Stop Lamp Relay
Stop Lamp Relay harness is open or shorted
Stop Lamp Relay circuit poor electrical connection
Faulty Body Control Module (BCM)

How to Fix the DTC B3903 Pontiac?

Review the 'Possible Causes' above and visually examine the corresponding wiring harness and connectors. Check for damaged components and inspect connector pins for signs of being broken, bent, pushed out, or corroded.

What does this mean?

Code Tech Notes

B3903 02 Stop Lamp Relay Circuit Short to Ground
B3903 05 Stop Lamp Relay Circuit Short to Battery or Open

What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the B3903 Pontiac code, it typically requires 1.0 hour of labor. Rates vary by location, vehicle, and shop. Many shops charge between $80–$150 per hour; dealerships and metro areas may be higher, independents may be lower.

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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.