AutoCodes – GMC – U18B8 GMC

U18B8 GMC Code - Lost Communication With Body Control Module On High Speed CAN Bus

Quick Answer

Devices connected to the serial data circuits monitor for serial data communications during normal vehicle operation. Common causes include Faulty Body Control Module (BCM), Body Control Module harness is open or shorted, Body Control Module 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: U18B8 GMC indicates Lost Communication With Body Control Module On High Speed CAN Bus.
Common causes: Common causes include Faulty Body Control Module (BCM), Body Control Module harness is open or shorted, Body Control Module 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 520

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 Jun 09, 2020

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code U18B8 GMC Description

Devices connected to the serial data circuits monitor for serial data communications during normal vehicle operation. Operating information and commands are exchanged among the devices. The devices have prerecorded information about what messages are needed to be exchanged on the serial data circuits, for each virtual network. The messages are supervised and also, some periodic messages are used by the receiver device as an availability indication of the transmitter device. Each message contains the identification number of the transmitter device. The Diagnostic Trouble Code (DTC) will set a supervised periodic message that includes the transmitter device availability that has not been received.

OBDII Code U18B8 GMC - Lost Communication With Body Control Module On High Speed CAN Bus - AutoCodes.com — U18B8 GMC Code - Lost Communication With Body Control Module On High Speed CAN Bus

What does this mean?

What are the Possible Causes of the DTC U18B8 GMC?

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

How to Fix the DTC U18B8 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 U18B8 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.

Need more information about the U18B8 GMC 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 U18B8 GMC Code

1. What are the common symptoms of OBDII code U18B8 GMC?

- Common symptoms include malfunctioning power windows, door locks, lighting issues, and failure of various body control functions.

2. What could cause the OBDII code U18B8 GMC to appear?

- The code may appear due to a faulty body control module, damaged wiring harness, loose connections, or issues with the high-speed CAN bus communication network.

3. How can I diagnose the U18B8 GMC code related to the Body Control Module?

- A thorough diagnostic scan using an OBDII scanner can help pinpoint the exact cause by checking for communication errors with the body control module and other related components.

4. What are some repair tips for addressing the Lost Communication With Body Control Module code?

- Inspect and repair any damaged wiring or loose connections in the high-speed CAN bus network. Check for corrosion on connectors and ensure proper grounding of the body control module.

5. Can driving with the U18B8 GMC code present cause any further damage to the vehicle?

- Continuing to drive with the code may lead to further malfunctions of critical body control functions and can potentially affect the overall performance and safety of the vehicle.

6. Is it safe to reset the U18B8 GMC code using an OBDII scanner without addressing the underlying issue?

- Resetting the code without diagnosing and repairing the root cause may temporarily clear the warning light, but the underlying issue will persist and may lead to recurring problems.

7. How much does it typically cost to repair the U18B8 GMC code related to the Body Control Module?

- The cost of repair can vary depending on the cause of the issue, but it may involve replacing the body control module, repairing wiring harnesses, or addressing other related components. Costs can range from a few hundred to over a thousand dollars.

8. Can I fix the U18B8 GMC code issue myself, or do I need to take it to a professional mechanic?

- While diagnosing and repairing the code may require advanced knowledge and tools, experienced DIYers with automotive repair skills may be able to address the issue. However, seeking professional help is recommended for accurate diagnosis and effective repairs.

9. Are there any recalls or technical service bulletins related to the U18B8 GMC code for specific vehicle models?

- It's advisable to check with the manufacturer, dealership, or online resources for any recalls or technical service bulletins related to the U18B8 GMC code, as certain vehicle models may have known issues or remedies provided by the manufacturer.

10. How can I prevent the U18B8 GMC code from reoccurring in the future?

- Regular maintenance, inspecting wiring harnesses for damage, ensuring proper connections, and addressing any underlying issues promptly can help prevent the U18B8 GMC code from reoccurring in the future.