AutoCodes – GMC – B0508 GMC

B0508 GMC Code - Short To Voltage Or BCM Open Internally In The LH DRL Relay Control Circuit

Quick Answer

The Body Control Module (BCM) provides control for the LH DRL relay circuit. Common causes include Faulty Left Daylight Running Lamp (DRL) Relay, Left Daylight Running Lamp (DRL) Relay harness is open or shorted, Left 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: B0508 GMC indicates Short To Voltage Or BCM Open Internally In The LH DRL Relay Control Circuit.
Common causes: Common causes include Faulty Left Daylight Running Lamp (DRL) Relay, Left Daylight Running Lamp (DRL) Relay harness is open or shorted, Left 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 775

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 B0508 GMC Description

The Body Control Module (BCM) provides control for the LH DRL relay circuit. The BCM grounds the Left Daylight Running Lamp (DRL) relay control circuit in order to energize the LH DRL relay and turn ON the LF turn signal This allows the LF turn signal to be used for DRL and approach lighting functions. The BCM monitors the voltage level on the LH DRL relay control circuit. When the BCM commands the relay ON, the voltage level on the LH DRL relay control circuit should be low. When the relay is OFF, the voltage on the LH 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 B0508 GMC - Short To Voltage Or BCM Open Internally In The LH DRL Relay Control Circuit - AutoCodes.com — B0508 GMC Code - Short To Voltage Or BCM Open Internally In The LH DRL Relay Control Circuit

What does this mean?

What are the Possible Causes of the DTC B0508 GMC?

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

How to Fix the DTC B0508 GMC?

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 B0508 GMC 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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Need Help with the Code?

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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 B0508 GMC Code

1. What are the common symptoms of OBDII code B0508 in a GMC vehicle?

- Common symptoms include the daytime running lights (DRL) not functioning properly, flickering DRLs, or the DRL indicator light staying on.

2. What does the OBDII code B0508 in a GMC indicate?

- OBDII code B0508 indicates a Short to Voltage or BCM Open Internally in the LH DRL Relay Control Circuit.

3. What are the possible causes of OBDII code B0508 in a GMC?

- Possible causes include a short to voltage in the LH DRL relay control circuit, an internally open BCM (Body Control Module), or a faulty LH DRL relay.

4. How can I diagnose the OBDII code B0508 in my GMC vehicle?

- Diagnose the code by checking the wiring and connections in the LH DRL relay control circuit, testing the LH DRL relay, and inspecting the BCM for any internal faults.

5. Can I still drive my GMC with OBDII code B0508?

- It is not recommended to drive the vehicle with unresolved DRL issues, as they are important for visibility and safety on the road.

6. How can I repair OBDII code B0508 in my GMC?

- Repair the code by addressing the root cause, which may involve repairing or replacing the LH DRL relay, repairing wiring issues, or replacing the BCM if necessary.

7. Will resetting the OBDII code B0508 make it go away permanently?

- Resetting the code may temporarily clear the warning light, but if the underlying issue is not fixed, the code is likely to return.

8. Can a DIY enthusiast fix OBDII code B0508 in a GMC?

- Depending on the skill level and tools available, a DIY enthusiast may be able to diagnose and repair OBDII code B0508, especially if it involves simple wiring repairs.

9. How important is it to address OBDII code B0508 promptly?

- It is essential to address the code promptly to ensure the proper functioning of the daytime running lights and maintain road safety.

10. Is OBDII code B0508 specific to GMC vehicles only?

- OBDII code B0508 is specific to GMC vehicles and relates to issues with the LH DRL relay control circuit in those particular models.

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