AutoCodes – Buick – U0129 Buick

U0129 Buick Code - Lost Communication with Brake System Control Module

Quick Answer

Modules connected to the high speed General Motor Local Area Network (GMLAN) serial data circuits monitor for serial data communications during normal vehicle operation. Common causes include Faulty Brake System Control Module, Brake System Control Module harness is open or shorted, Brake System 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: U0129 Buick indicates Lost Communication with Brake System Control Module.
Common causes: Common causes include Faulty Brake System Control Module, Brake System Control Module harness is open or shorted, Brake System 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 1,692

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 Apr 01, 2020

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code U0129 Buick Description

Modules connected to the high speed General Motor Local Area Network (GMLAN) serial data circuits monitor for serial data communications during normal vehicle operation. Operating information and commands are exchanged among the modules. The modules 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 module as an availability indication of the transmitter module. The supervision time-out period is 250 ms. Each message contains the identification number of the transmitter module. The Diagnostic Trouble Code (DTC) sets when a periodic message from the Brake System Control Module has not been received.

OBDII Code U0129 Buick - Lost Communication with Brake System Control Module - AutoCodes.com — U0129 Buick Code - Lost Communication with Brake System Control Module

What does this mean?

What are the Possible Causes of the DTC U0129 Buick?

Faulty Brake System Control Module
Brake System Control Module harness is open or shorted
Brake System Control Module circuit poor electrical connection

How to Fix the DTC U0129 Buick?

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 U0129 Buick 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 U0129 Buick Code

1. What does the OBDII code U0129 for a Buick mean?

The U0129 code indicates that there is a communication problem between the vehicle's main computer and the Brake System Control Module.

2. What are the common symptoms of a U0129 code in a Buick?

Common symptoms include the ABS light or traction control light coming on, loss of communication with the brake system module, and potential issues with the vehicle's braking system.

3. What are the possible causes of a U0129 code in a Buick?

Potential causes may include a faulty Brake System Control Module, damaged wiring or connectors in the communication network, a software glitch, or a problem with the vehicle's main computer.

4. How can I diagnose a U0129 code in my Buick?

Diagnosis typically involves using a diagnostic scanner to read the code, checking the connections and wiring to the Brake System Control Module, and performing a thorough inspection of the brake system components.

5. Can I still drive my Buick with a U0129 code present?

It is not recommended to drive the vehicle with a U0129 code present, as it may affect the proper functioning of the brake system and compromise safety.

6. How can I repair a U0129 code in my Buick?

Repairing a U0129 code may involve repairing or replacing damaged wiring or connectors, resetting the main computer, reprogramming the Brake System Control Module, or replacing the faulty module.

7. Will a U0129 code cause my Buick to fail an emissions test?

A U0129 code is not directly related to emissions, so it should not cause your Buick to fail an emissions test. However, it is still essential to address the underlying issue for proper vehicle performance.

8. How much does it typically cost to repair a U0129 code in a Buick?

The cost of repairing a U0129 code can vary depending on the exact cause of the issue, the labor rates in your area, and whether any parts need to be replaced. It is advisable to consult a mechanic for an accurate estimate.

9. Can a U0129 code be a recurring issue in a Buick?

If the underlying problem causing the U0129 code is not fully resolved, it can potentially reoccur. Proper diagnosis and repair are essential to prevent the issue from happening again.

10. Is it possible to clear a U0129 code in a Buick without fixing the underlying problem?

While you can clear the code temporarily using a diagnostic scanner, the issue will likely return if the root cause is not addressed. It is crucial to repair the problem to ensure the code does not reappear.