AutoCodes – Generic – B0503

B0503 Code - Short To Voltage Or BCM Open Internally In The RH DRL Relay Control Circuit

Quick Answer

The Body Control Module (BCM) provides control for the Right Daylight Running Lamp (DRL) relay circuit. Common causes include Faulty Right Daylight Running Lamp (DRL) Relay, Right Daylight Running Lamp (DRL) Relay harness is open or shorted, Right Daylight Running Lamp (DRL) Relay circuit poor electrical connection. Severity is Low - monitor the vehicle and repair when practical. The vehicle can usually be driven if no severe symptoms are present, but symptoms should be checked before extended driving.

What it means: B0503 indicates Short To Voltage Or BCM Open Internally In The RH DRL Relay Control Circuit.
Common causes: Common causes include Faulty Right Daylight Running Lamp (DRL) Relay, Right Daylight Running Lamp (DRL) Relay harness is open or shorted, Right Daylight Running Lamp (DRL) Relay circuit poor electrical connection.
Severity: Low - monitor the vehicle and repair when practical.
Can I drive?: The vehicle can usually be driven if no severe symptoms are present, but symptoms should be checked before extended driving.

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Code Popularity 1,953

How popular is this code, among other codes? Low

Repair Importance Level

Low (Monitor) (1 / 3)

Repair Difficulty Level

Intermediate (2 / 3)

What is this?

Table of contents Created and updated by William Orellana on Mar 11, 2021

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code B0503 Description

The Body Control Module (BCM) provides control for the Right Daylight Running Lamp (DRL) relay circuit. The BCM grounds the RH DRL relay control circuit in order to energize the RH DRL relay and turn ON the RF turn signal. This allows the RF turn signal to be used for DRL and approach lighting functions. The BCM monitors the voltage level on the RH DRL relay control circuit. When the BCM commands the relay ON, the voltage level on the RH DRL relay control circuit should be low. When the relay is OFF, the voltage on the RH DRL relay control circuit should be high. If the BCM detects a voltage level other than expected, a malfunction is present and a Diagnostic Trouble Code (DTC) will set.

OBDII Code B0503 - Short To Voltage Or BCM Open Internally In The RH DRL Relay Control Circuit - AutoCodes.com — B0503 Code - Short To Voltage Or BCM Open Internally In The RH DRL Relay Control Circuit

What does this mean?

What are the Possible Causes of the DTC B0503?

Faulty Right Daylight Running Lamp (DRL) Relay
Right Daylight Running Lamp (DRL) Relay harness is open or shorted
Right Daylight Running Lamp (DRL) Relay circuit poor electrical connection
Faulty Body Control Module (BCM)

How to Fix the DTC B0503?

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 is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the B0503 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.

Need more information about the B0503 code?

Need more information on how to fix the B0503 code? Get Access to Factory Service Manuals

Need Help with the Code?

Get the B0503 code diagnosed by a professional: Find a repair shop in your area

Information for Specific Makes

B0503 Buick — Short To Voltage Or BCM Open Internally In The RH DRL Relay Control Circuit
B0503 Cadillac — Short To Voltage Or BCM Open Internally In The RH DRL Relay Control Circuit
B0503 Chevrolet — Short To Voltage Or BCM Open Internally In The RH DRL Relay Control Circuit
B0503 GMC — Short To Voltage Or BCM Open Internally In The RH DRL Relay Control Circuit

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 B0503 Code

1. What are the common symptoms of OBDII code B0503?

- Common symptoms include the right headlight not working, the daytime running lights malfunctioning, or a dashboard warning light indicating an issue with the RH DRL relay control circuit.

2. What causes the OBDII code B0503 to trigger?

- The code B0503 can be triggered by a short to voltage in the circuit or an internal open in the Body Control Module (BCM) related to the right headlight's daytime running light relay control.

3. How can I diagnose the OBDII code B0503?

- Diagnosing code B0503 involves inspecting the wiring and connectors related to the RH DRL relay control circuit, checking the relay itself, and testing the BCM for internal faults.

4. What are some potential repair tips for resolving OBDII code B0503?

- Repairing code B0503 may involve repairing or replacing damaged wiring, repairing or replacing the RH DRL relay, or reprogramming the BCM if an internal fault is detected.

5. Can I drive my vehicle with OBDII code B0503?

- It is not recommended to drive your vehicle with code B0503, as it may lead to safety issues like non-functional daytime running lights or a malfunctioning right headlight.

6. How do I reset the OBDII code B0503 after making repairs?

- After making the necessary repairs to address code B0503, you can reset the code using an OBDII scanner or by disconnecting the vehicle's battery for a few minutes.

7. Is OBDII code B0503 a serious issue?

- While code B0503 may not directly affect the drivability of the vehicle, it is essential to address this issue promptly to ensure proper operation of the right headlight's daytime running light system.

8. Can a DIY enthusiast fix OBDII code B0503?

- Depending on your experience and access to tools, a DIY enthusiast may be able to address code B0503 by following a repair manual specific to their vehicle make and model.

9. How much does it typically cost to repair OBDII code B0503 at a repair shop?

- The cost to repair code B0503 at a repair shop can vary depending on the extent of the issue, parts needed for replacement, and labor rates, but it may range from $100 to $300.

10. Will fixing OBDII code B0503 improve my vehicle's overall performance?

- Fixing code B0503 may not directly impact the performance of your vehicle but will ensure the proper functioning of the right headlight's daytime running light system, enhancing safety and visibility while driving.