AutoCodes – GMC – U0029 GMC

U0029 GMC 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 GMC 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 2,166

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

What does this mean?

What are the Possible Causes of the DTC U0029 GMC?

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

How to Fix the DTC U0029 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 U0029 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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Information for Specific GMC Models

U0029 2014 GMC Sierra — Media Oriented Systems Transport Bus Performance
U0029 2015 GMC Sierra — Media Oriented Systems Transport Bus Performance
U0029 2016 GMC Sierra — Media Oriented Systems Transport Bus Performance
U0029 2017 GMC Sierra — Media Oriented Systems Transport Bus Performance
U0029 2018 GMC Sierra — Media Oriented Systems Transport Bus Performance

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 GMC Code

1. What are the common symptoms of OBDII code U0029 GMC?

The common symptoms of code U0029 GMC include issues with the Media Oriented Systems Transport (MOST) Bus system, such as audio system malfunctions, navigation system errors, or communication failures between various vehicle components.

2. What are the possible causes of OBDII code U0029 GMC?

Possible causes of code U0029 GMC can include a faulty MOST Bus communication network, damaged wiring or connectors in the MOST system, a defective control module, or software glitches within the vehicle's entertainment system.

3. How can I diagnose OBDII code U0029 GMC?

Diagnosing code U0029 GMC typically involves using a diagnostic scanner to read the fault codes stored in the vehicle's computer system. Additionally, a thorough inspection of the MOST Bus components, wiring, and connectors may be necessary to pinpoint the exact cause of the issue.

4. Can I drive my vehicle with OBDII code U0029 GMC active?

While the vehicle may still be operational with code U0029 GMC present, it is not recommended to drive with unresolved issues related to the MOST Bus system. Continuing to drive the vehicle without addressing the problem may lead to further damage or malfunctions in the vehicle's entertainment and communication systems.

5. How can I repair OBDII code U0029 GMC?

Repairing code U0029 GMC may involve fixing or replacing damaged wiring or connectors in the MOST Bus network, updating software in the control modules, or replacing faulty components within the entertainment system. It is advisable to consult a professional mechanic for an accurate diagnosis and repair.

6. Is OBDII code U0029 GMC a common issue in GMC vehicles?

Code U0029 related to the Media Oriented Systems Transport (MOST) Bus is more commonly found in vehicles equipped with advanced audio and navigation systems, such as certain GMC models. However, it is not as common as other OBDII codes related to engine or emissions systems.

7. How much does it cost to repair OBDII code U0029 GMC?

The cost of repairing code U0029 GMC can vary depending on the exact cause of the issue, the extent of the damage, and the labor rates of the repair shop. It is recommended to obtain a few quotes from different mechanics to compare prices before proceeding with the repair.

8. Can a DIY enthusiast fix OBDII code U0029 GMC?

While some basic troubleshooting steps like checking fuses or connectors can be performed by DIY enthusiasts, diagnosing and repairing code U0029 GMC related to the MOST Bus system may require specialized tools and knowledge. It is best to consult a professional mechanic for accurate diagnosis and repair.

9. Will resetting the OBDII code U0029 GMC make it go away permanently?

Simply resetting the OBDII code U0029 GMC may clear the warning light temporarily, but if the underlying issue with the MOST Bus system is not addressed and repaired, the code is likely to reappear. It is crucial to diagnose and fix the root cause of the problem for a permanent solution.

10. How long does it typically take to repair OBDII code U0029 GMC?

The time required to repair code U0029 GMC can vary depending on the complexity of the diagnosis and the extent of the repairs needed. In some cases, it may be a quick fix, while in others, it could take several hours or even days to fully resolve the issue.