AutoCodes – GMC – B0985 GMC

B0985 GMC Code - Right Headlamp Light Distribution Shutter Control Circuit Malfunction

Quick Answer

Battery positive voltage is applied to the headlamp control module at all times. Common causes include Faulty Right Headlamp Assembly, Right Headlamp Assembly harness is open or shorted, Right Headlamp Assembly 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: B0985 GMC indicates Right Headlamp Light Distribution Shutter Control Circuit Malfunction.
Common causes: Common causes include Faulty Right Headlamp Assembly, Right Headlamp Assembly harness is open or shorted, Right Headlamp Assembly 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 1,030

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 11, 2021

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code B0985 GMC Description

Battery positive voltage is applied to the headlamp control module at all times. The headlamp control module has a normal operational voltage range of about 12.5-16 V and is only fully functional with the ignition switch is in the RUN position and the headlamp switch in the AUTO position. The communications enable signal from the Body Control Module (BCM) wakes the headlamp control module microprocessor. The headlamp control module receives serial data messages from the Engine Control Module (ECM), Transmission Control Module (TCM), Electronic Brake Control Module (EBCM), and BCM with information regarding power mode, speed, steering angle, transmission gear selection, and headlamp switch status. The headlamp control module calculates the headlamp angle and sends commands to the left and right adaptive forward lighting system headlamp actuators. The headlamp actuators drive the headlamps to the position commanded by the headlamp control module. The headlamp control module monitors the headlamp actuator motor control circuits for proper circuit continuity and for shorts to ground or voltage. If a malfunction is detected, a DTC will be stored in memory and the driver will be notified with a message displayed over the driver information center located on the instrument cluster.

OBDII Code B0985 GMC - Right Headlamp Light Distribution Shutter Control Circuit Malfunction - AutoCodes.com — B0985 GMC Code - Right Headlamp Light Distribution Shutter Control Circuit Malfunction

What does this mean?

What are the Possible Causes of the DTC B0985 GMC?

Faulty Right Headlamp Assembly
Right Headlamp Assembly harness is open or shorted
Right Headlamp Assembly circuit poor electrical connection

How to Fix the DTC B0985 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 B0985 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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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 B0985 GMC Code

1. What are common symptoms of OBDII code B0985 GMC?

- Common symptoms include a malfunctioning right headlamp light distribution shutter, uneven headlight beam pattern, and the headlight not adjusting properly.

2. What causes the Right Headlamp Light Distribution Shutter Control Circuit Malfunction (B0985) in a GMC vehicle?

- The most common causes of this code are faulty distribution shutter control module, damaged wiring or connectors, or a defective light distribution shutter motor.

3. How can I diagnose OBDII code B0985 related to the right headlamp light distribution shutter in my GMC?

- To diagnose this code, you can use a diagnostic scanner to retrieve the specific trouble code, inspect the wiring and connectors for any damage, and test the functionality of the light distribution shutter motor.

4. Can I still drive my GMC with OBDII code B0985 present?

- It is not recommended to drive your vehicle with this code present, as it can affect the proper functioning of your right headlamp and compromise visibility, especially at night.

5. How can I repair the Right Headlamp Light Distribution Shutter Control Circuit Malfunction in my GMC?

- Repair options may include replacing the distribution shutter control module, repairing or replacing damaged wiring or connectors, and replacing the light distribution shutter motor if necessary.

6. Will resetting the OBDII code B0985 clear the issue with the right headlamp light distribution shutter?

- Resetting the code may temporarily clear the warning light, but it will not fix the underlying issue causing the malfunction in the right headlamp light distribution shutter.

7. Is it safe to attempt DIY repairs for OBDII code B0985 in my GMC?

- If you have experience with automotive electrical systems and the necessary tools, you may attempt DIY repairs. However, consulting a professional mechanic is recommended for accurate diagnosis and proper repair.

8. Can extreme weather conditions contribute to the Right Headlamp Light Distribution Shutter Control Circuit Malfunction?

- Yes, extreme weather conditions such as heavy rain or snow can potentially damage the wiring or connectors related to the right headlamp light distribution shutter, leading to this malfunction.

9. How long does it typically take to repair the Right Headlamp Light Distribution Shutter Control Circuit Malfunction in a GMC?

- The repair time can vary depending on the exact cause of the issue, but on average, it may take a few hours to a full day to diagnose and repair the right headlamp light distribution shutter malfunction.

10. Are there any preventive maintenance tips to avoid OBDII code B0985 in the future?

- Regularly inspecting the headlamp components, ensuring proper connections, and addressing any electrical issues promptly can help prevent the recurrence of the Right Headlamp Light Distribution Shutter Control Circuit Malfunction in your GMC.