AutoCodes – GMC – U0029 2018 GMC Sierra

U0029 2018 GMC Sierra Code - Media Oriented Systems Transport Bus Performance

Quick Answer

The Media Oriented Systems Transport (MOST) bus consists of a physical ring in which multimedia devices share audio, video and infotainment system control data. Common causes include Faulty Audio Unit (Radio), Audio Unit harness is open or shorted, Audio Unit 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: U0029 2018 GMC Sierra indicates Media Oriented Systems Transport Bus Performance.
Common causes: Common causes include Faulty Audio Unit (Radio), Audio Unit harness is open or shorted, Audio Unit 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 297

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 Jul 19, 2023

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code U0029 2018 GMC Sierra Description

The Media Oriented Systems Transport (MOST) bus consists of a physical ring in which multimedia devices share audio, video and infotainment system control data. Each device on the MOST bus transmits and receives data via the MOST Bus Serial Data (+/- transmit/receive) circuits. The MOST bus diagnostic master is the Radio. The MOST control circuit is connected to each device on the MOST bus. Each device provides a 12 V signal on the MOST control circuit. The Radio initiates communication on the MOST bus at Ignition ON by toggling the MOST control circuit low for 100 ms. Once each device recognizes the wakeup signal from the Radio on the MOST control circuit, they will respond to the Radio on the MOST bus to indicate no faults are present and normal communications will commence. The MOST bus master device shall set DTC U0029 when the MOST bus interruptions last long enough to interrupt MOST communication and functions, but not long enough to break the MOST bus ring. A current Diagnostic Trouble Code (DTC) sets when MOST bus communication has been interrupted more than 10 times during the monitoring cycle period.

OBDII Code U0029 2018 GMC Sierra - Media Oriented Systems Transport Bus Performance - AutoCodes.com — U0029 2018 GMC Sierra Code - Media Oriented Systems Transport Bus Performance

What does this mean?

What are the Possible Causes of the DTC U0029 2018 GMC Sierra?

Faulty Audio Unit (Radio)
Audio Unit harness is open or shorted
Audio Unit circuit poor electrical connection

How to Fix the DTC U0029 2018 GMC Sierra?

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 U0029 2018 GMC Sierra 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 U0029 2018 GMC Sierra Code

1. What does the OBDII code U0029 mean on a 2018 GMC Sierra?

U0029 refers to a "Media Oriented Systems Transport (MOST) Bus Performance" issue, indicating a communication problem on the MOST bus network, which connects multimedia components.

2. What are the common symptoms of code U0029 in a 2018 GMC Sierra?

Symptoms may include a non-functional infotainment system, loss of audio or video output, trouble connecting to Bluetooth devices, or an unresponsive navigation system.

3. What causes the U0029 code to appear on a GMC Sierra?

The code can be triggered by a faulty component on the MOST bus, damaged wiring or connectors, software glitches, or a failed infotainment control module.

4. Can a loose connection cause the U0029 code?

Yes, loose or corroded connectors in the MOST bus network can disrupt communication and trigger the code.

5. How is code U0029 diagnosed on a 2018 GMC Sierra?

A technician uses a scan tool to check for related codes, inspects the MOST bus wiring and connectors, and tests individual components on the network for proper communication.

6. Can a software update resolve the U0029 code?

In some cases, a software update for the infotainment or control module may fix communication issues and clear the code.

7. Is it safe to drive with the U0029 code present?

Yes, the U0029 code typically affects non-essential features like the infotainment system and does not impact vehicle safety or drivability.

8. How can I fix the U0029 code on my 2018 GMC Sierra?

Repairs may involve checking and repairing wiring, replacing defective modules or components on the MOST bus, or performing a software update.

9. What tools are needed to troubleshoot the U0029 code?

A scan tool capable of reading manufacturer-specific codes and accessing the MOST system, along with basic tools to inspect wiring and connectors, are required.

10. Can a faulty infotainment control module cause the U0029 code?

Yes, a malfunctioning infotainment control module can disrupt the MOST bus communication and trigger the U0029 code.